Knife Review: Whitby & Co Dive Knives – DK9, DK11 and DK511/14 (Dive Knives 2016 – Detail Review)

This review provides further details for the three Whitby & Co Dive Knife models DK9, DK11 and DK511/14 which could not be included in the Dive Knives 2016 – Mega Test Review

 photo 49 whitby Group sheathed P1210772.jpg

The Blade and Handle Geometry:

Most knife specifications have a basic description of the blade geometry, but in this section I will be taking a more detailed look at geometry and balance.

Using a set of gauges and precision measuring equipment including a Vernier protractor, callipers, fixed radius gauges and the unique Arc Master adjustable radius gauge (the one that looks like a crossbow).
 photo Knife measuring P1180483.jpg

These measurements have been tabulated and are presented along with other blades.

Key aspects such as the primary bevel angle, grind type, blade depth, blade thickness, length, weight are detailed, along with balance information.

The ‘Balance relative to the front of the handle’ tells you if the knife will feel front heavy, or if the weight is in your hand (a positive value means the weight is forward of the front of the handle). The ‘Balance relative to the centre of the handle’ indicates how close to a ‘neutral balance’ the knife has in the hand.

In the case of full convex grinds the approximate centre of the grind is used for the primary bevel angle estimate.

The measurements are presented alongside some of the other knives from the Dive Knives 2016 – Mega Test Review

There are three Whitby knives, and these have been logged across two comparison tables.
 photo Dive Knives Parameters 2 of 3.jpg

 photo Dive Knives Parameters 3 of 3.jpg

A few more details of the DK9:

Before we really get going looking at the details, you might be curious as to these being Whitby & Co knives yet coming in alternately branded packaging. Whitby & Co source some of the foremost international brands and supply Trade customers with these products.
 photo 01 whitby boxed P1210566.jpg

The knives on test here are referred to under their Whitby & Co model numbers.
 photo 02 whitby label P1210568.jpg

Starting with the smallest of the Whitby dive knives, the DK9, it is supplied with two rubber straps with quick release buckles and a leaflet.
 photo 03 whitby DK9 contents P1210576.jpg

On the back of the box are the instructions for assembling the straps. This is the same for all the models on test here.
 photo 04 whitby DK9 instructions P1210579.jpg

One end of the rubber strap is moulded so that it won’t pull through the buckle.
 photo 05 whitby DK9 strap detail P1210581.jpg

Onto the DK9 itself, this is exactly as it comes out of the box, in its sheath.
 photo 06 whitby DK9 sheathed P1210584.jpg

The knife construction is a single piece of flat stock steel. Being a typical dagger design with shapr point and double edge, it has no diving safety features that would make it safe for cutting away entanglements from the body.
 photo 07 whitby DK9 unsheathed P1210589.jpg

The sheath consists of two moulded plastic halves riveted together. Each side has a slot to fit the rubber straps into.
 photo 08 whitby DK9 sheath P1210591.jpg

At the top of the front piece of the sheath are a couple of plastic hooks which hold the DK9 in the sheath.
 photo 09 whitby DK9 sheath retention P1210595.jpg

With the knife inserted you can see how the plastic hooks fit over the guard.
 photo 18 whitby DK9 retention P1210637.jpg

The back of the sheath is a simple flat plastic surface.
 photo 10 whitby DK9 sheath back P1210597.jpg

Let’s start looking round the knife. From this overall view, notice that in the handle and blade are two types of shackle wrench cut-out and the knife is a one piece all metal construction.
 photo 11 whitby DK9 angle P1210602.jpg

Having a typical dagger grind, there are no sharp corners/edges to the plunge lines.
 photo 12 whitby DK9 plunge P1210604.jpg

One side of the double edged blade has some very effective serrations.
 photo 13 whitby DK9 serrations P1210607.jpg

The serrations are formed with a single bevel, so when looking at the back, there is no visible edge bevel.
 photo 16 whitby DK9 serration back P1210622.jpg

Quick close-up of the blade tip.
 photo 14 whitby DK9 tip P1210612.jpg

A generous sized lanyard hole is included in the handle.
 photo 15 whitby DK9 lanyard P1210618.jpg

It is a relatively compact blade, and despite the thin handle is comfortable enough in the hand (I take XL gloves).
 photo 17 whitby DK9 in hand P1210632.jpg

There is room to fit both straps, but being so compact I found I only needed one and it stayed where I needed it.
 photo 19 whitby DK9 with straps P1210642.jpg

As quick-release buckles are used, you set the strap length to fit at which point they operate as fixed length straps. This is how the rubber is threaded through the adjustment side of the buckle.
 photo 20 whitby DK9 strap adjustment P1210647.jpg

A few more details of the DK11:

Taking a step up in size to the DK11, and we also take a step up in design and function. As with the DK9, the DK11 comes with two straps with quick-release buckles.
 photo 21 whitby DK11 contents P1210653.jpg

A more substantial package than the DK9. Note that there is a sliding lock for the knife release lever.
 photo 22 whitby DK11 sheathed P1210660.jpg

Box fresh and not yet subjected to the corrosion testing, the DK11 has a double edged blade with a line cutting hook.
 photo 23 whitby DK11 unsheathed P1210662.jpg

On the front of the sheath is a sprung knife retaining catch with a hook that engages with the knife handle.
 photo 24 whitby DK11 retention P1210665.jpg

Requiring a reasonable pressure, the retaining catch lifts away to release the knife.
 photo 25 whitby DK11 retention P1210669.jpg

The two halves of the plastic sheath are screwed together.
 photo 26 whitby DK11 sheath back P1210672.jpg

The spine of the blade has the serrations and cutting hook, and the DK11 also has a hammer pommel.
 photo 27 whitby DK11 angle P1210675.jpg

At the front of the handle a stainless steel curved guard is incorporated. There is what might be considered a finger choil in the ricasso, but this is not something I would use when diving.
 photo 28 whitby DK11 guard P1210678.jpg

A close-up of the blade tip and factory edge.
 photo 29 whitby DK11 tip P1210681.jpg

The serrations are a similar pattern to the DK9, but have three repeats of the smaller groove rather than two.
 photo 30 whitby DK11 serrations P1210684.jpg

Just as with the DK9, the serrations are formed with a single bevel, so from the other side have no visible bevel.
 photo 31 whitby DK11 serrations P1210687.jpg

A line cutter hook is included near the guard.
 photo 32 whitby DK11 line cutter P1210694.jpg

Despite its smooth lines, the handle is nice and grippy thanks to being rubber.
 photo 33 whitby DK11 handle P1210696.jpg

The blue plastic insert includes the knife retention catch point.
 photo 34 whitby DK11 retention catch P1210699.jpg

With the DK11 you have a good mid-sized all rounder blade.
 photo 35 whitby DK11 in hand P1210704.jpg

After threading the straps through the sheath, you still need to thread the loose end through the buckle.
 photo 36 whitby DK11 straps P1210705.jpg

A few more details of the DK511/14:

Lastly we have a bit of an old-school BFK (Big F’n Knife), the DK511/14. As before, there are two adjustable quick-release buckle straps included.
 photo 37 whitby DK511-14 contents P1210713.jpg

This is what the classic dive knife used to look like, and it still has a place today.
 photo 38 whitby DK511-14 sheathed P1210715.jpg

Again with the classic design we have a rubber ring fitting over the end of the handle to keep the knife in the sheath.
 photo 39 whitby DK511-14 retention P1210722.jpg

To release the knife just pull the ring off the handle using the tab provided.
 photo 40 whitby DK511-14 retention P1210726.jpg

Definitely not a compact blade, this is a full size traditional dive knife design.
 photo 41 whitby DK511-14 unsheathed P1210735.jpg

A real working blade, there are several useful features.
 photo 42 whitby DK511-14 angle P1210736.jpg

Very ‘saw-like’ serrations which shred rope, even if not cutting it cleanly.
 photo 43 whitby DK511-14 serrations P1210742.jpg

A close-up of the tip shows it could do with a little work, but actually not having a needle like point is safer for diving.
 photo 44 whitby DK511-14 tip P1210744.jpg

Unlike the hook type of line cutter, the DK511/14 has a much bigger line cutting feature with an elongated scallop which helps contain what you are cutting by preventing the line/rope from slipping off the cutting edge.
 photo 45 whitby DK511-14 line cutter P1210749.jpg

The handle is coffin shaped with a flared butt and guard.
 photo 46 whitby DK511-14 handle P1210757.jpg

Yeah, this is a BFK!
 photo 47 whitby DK511-14 in hand P1210761.jpg

You have a couple of options for strap positions, and the back of the one-piece sheath is shaped to fit your leg.
 photo 48 whitby DK511-14 with straps P1210768.jpg

What are they like to use?

By featuring these three models, this review covers a wide range of the styles of knife offered by Whitby. Not to be too generalistic I would class these three as a backup, general purpose and heavy duty type of knife.
 photo 54 whitby Group underwater P1000917.jpg

I’ll not cover the cutting again as this is detailed in the Dive Knives 2016 – Mega Test Review which you can check for more information on the cutting test results.

None of these dive knives has a blunt tip, which means you do need to take great care using them as a release knife. All of them also have double edged designs which again makes them very hazardous for release use especially if you have line or rope wrapped round you.

Price-wise the DK9 and DK511/14 come in at the low end of the scale, and the DK11 entering the low-mid price range. This is an important consideration as though not perfect, these have proven to be very good value.

Remember that the corrosion testing was tantamount to abuse for these knives. No cleanup, and no protection for the blades, just a highly corrosive environment.

Starting with the DK9, unsurprisingly, the rust has taken hold inside the sheath, and where the edge has been ground (leaving a rougher finish than the rest of the knife). With only two spots suffering significantly, very little of the cutting edge was damaged by this corrosion.
 photo 52 whitby DK9 rust P1230022.jpg

Next up the DK11. Though this does not look too bad, there is rust going into the handle, and around 30% of the edge has corroded. After re-sharpening this knife is was clear the edge had pitted and become damaged. The serrations however show no signs of rust and were unaffected.
 photo 51 whitby DK11 rust P1230016.jpg

Lastly the DK511/14 which was looking one of the worst. It was also the first to show signs of rust after only two hours immersion. The mirror finish on the blade has helped protect it, but the edge has suffered quite a lot of corrosion and pitting.
 photo 53 whitby DK511-14 rust P1230029.jpg

These knives definitely need a little care and attention and should be cleaned and have grease applied to protect the blades.

Of the three, the DK9 felt very appropriate as a forearm mounted backup blade. Small, easy to forget you are wearing it, and importantly, being on the arm it is easier to watch as you re-sheath it – that point is wicked and will bite you if you are not careful.

The retention system was the least easy to use as you pretty much had to drag the knife out and push it home like a friction fit. Getting gloved fingers under the plastic clips was unreliable.
 photo 55 whitby DK9 arm P1000944.jpg

Going to a leg mount with the DK11, on dry land, the knife release catch was the stiffest of all the sprung clip designs and I thought it would make things a struggle in the water. It was much easier to work with once strapped to your leg, but still not as easy as I would really like. One winning, and unique, feature is the sliding lock. It really did give peace of mind to know that the blade was positively locked into the sheath, and unlocking to then allow the blade to be released was easy.
 photo 56 whitby DK11 leg P1000953.jpg

Lastly the DK511/14 which takes up much more room on your leg. With the rubber retaining ring pulled off the knife handle, the knife actually rattles around in the sheath and will fall out if the sheath is tipped up. This is unlike the other two where simply fully inserting the knife will lock it into the sheath – you have to watch this and make sure you re-fit the rubber retaining strap. There is a time and a place for a big knife, and the DK511/14 gives you a lot of blade for the money.
 photo 57 whitby DK511-14 leg P1000952.jpg

Review Summary

The views expressed in this summary table are from the point of view of the reviewer’s personal use. I am not a member of the armed forces and cannot comment on its use beyond a cutting tool or field/hunting knife.

Something that might be a ‘pro’ for one user can be a ‘con’ for another, so the comments are categorised based on my requirements. You should consider all points and if they could be beneficial to you.

_______________________________________________ _______________________________________________
Things I like What doesn’t work so well for me
_______________________________________________ _______________________________________________
Excellent cutting results from the DK9 None of the models are safe for ‘release’ tasks due to sharp points a double edged blades.
The DK11 has a locking system to ensure the blade is secure. All models suffered edge damage from corrosion.
Good value. DK511/14 knife retention is fiddly to use.
Effective rubber straps.
Sizes from Compact to BFK to choose from.

 photo 50 whitby Group unsheathed P1210778.jpg

 

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Knife Review: Promate Dive Knives – Barracuda, Scuba, Seal Folder, KF505 Blunt and Line Cutter (Dive Knives 2016 – Detail Review)

This review provides further details for the five Promate dive knives (Barracuda Blunt Ti, KF593 Ti, KF090 Seal Folder Ti, KF505 Blunt and KF001 Line Cutter) which could not be included in the Dive Knives 2016 – Mega Test Review. Promate is a Full line manufacturer of scuba diving equipment and snorkeling gear including regulators, instruments, buoyancy compensators, masks, snorkels, fins, knives, boots, gloves and bags.

 photo 87 Promate intro P1210559.jpg

The Blade and Handle Geometry:

Most knife specifications have a basic description of the blade geometry, but in this section I will be taking a more detailed look at geometry and balance.

Using a set of gauges and precision measuring equipment including a Vernier protractor, callipers, fixed radius gauges and the unique Arc Master adjustable radius gauge (the one that looks like a crossbow).
 photo Knife measuring P1180483.jpg

These measurements have been tabulated and are presented along with other blades.

Key aspects such as the primary bevel angle, grind type, blade depth, blade thickness, length, weight are detailed, along with balance information.

The ‘Balance relative to the front of the handle’ tells you if the knife will feel front heavy, or if the weight is in your hand (a positive value means the weight is forward of the front of the handle). The ‘Balance relative to the centre of the handle’ indicates how close to a ‘neutral balance’ the knife has in the hand.

In the case of full convex grinds the approximate centre of the grind is used for the primary bevel angle estimate.

The measurements are presented alongside some of the other knives from the Dive Knives 2016 – Mega Test Review

As there are five Promate cutting tools, these are logged across two tables.
 photo Dive Knives Parameters 1 of 3.jpg

 photo Dive Knives Parameters 2 of 3.jpg

A few more details of the KF001 Line Cutter:

There are five models from Promate and a huge amount of detail to cover, so each one will have its own “A few more details…” section.
 photo 01 Promate boxed P1210106.jpg

The first two we will look at are the ones that are not fixed blade sheath knives, the Seal Folder and Line Cutter.
 photo 02 Promate first two P1210122.jpg

Fresh out of the box.
 photo 03 Promate first two unboxed P1210127.jpg

A small container is supplied with the line cutter.
 photo 04 Promate line cutter P1210131.jpg

This contains two spare blades wrapped in oil paper.
 photo 06 Promate line cutter spare blade P1210138.jpg

A close up of the blade in the line cutter.
 photo 05 Promate line cutter blade P1210137.jpg

Taking out the three screws holding the line cutter together allows you to see how the standard utility blade fits inside.
 photo 07 Promate line cutter blade swap P1210158.jpg

It is a generous size so is easy to handle.
 photo 08 Promate line cutter in hand P1210161.jpg

A few more details of the KF090 Seal Folder Ti:

An adjustable wrist strap is supplied fitted to the Seal folder.
 photo 09 Promate Ti Folder P1210165.jpg

The pivot is riveted and cannot be adjusted.
 photo 10 Promate Ti Folder pivot P1210167.jpg

On one side there is a plastic pocket clip.
 photo 11 Promate Ti Folder clip P1210168.jpg

From this side you can see the blade pivot and lock bar pivot rivet heads.
 photo 12 Promate Ti Folder pivot rivet P1210173.jpg

As a specialist knife, the Seal folder has an unusual cutting hook which is accessible even with the blade folded.
 photo 13 Promate Ti Folder folded P1210178.jpg

A closer look at the cutting hook.
 photo 14 Promate Ti Folder hook P1210181.jpg

The blade is part serrated and there is a small thumb opening hole.
 photo 15 Promate Ti Folder open P1210184.jpg

In case you had forgotten, it is made of titanium. The serrations are well formed.
 photo 17 Promate Ti Folder serration P1210192.jpg

When you look at the reverse of the blade, you can see that this knife uses only a single bevel edge.
 photo 18 Promate Ti Folder blade back P1210200.jpg

Going in closer to the back of the serrations.
 photo 19 Promate Ti Folder serration back P1210201.jpg

And also the plain edge.
 photo 20 Promate Ti Folder plain back P1210206.jpg

Not a large knife, the Seal folder is still a comfortable size.
 photo 21 Promate Ti Folder in hand P1210212.jpg

A few more details of the Barracuda Blunt Ti:

Promate’s Barracuda comes in Steel and Titanium versions, as well as blunt and pointed tips. The fully diving orientated blade design with Titanium and a blunt tip was chosen for the review.
 photo 23 Promate Barracuda boxed P1210224.jpg

Supplied with the knife are two rubber straps and an instruction leaflet.
 photo 24 Promate Barracuda box contents P1210227.jpg

The strap has quick release buckles.
 photo 25 Promate Barracuda strap clip P1210235.jpg

Each buckle has a sprung loaded adjustment clip to grip the rubber strap.
 photo 26 Promate Barracuda strap adjust P1210239.jpg

A strap in its fully assembled state. However this now cannot be fitted to the sheath. You need to take it apart, thread it through the slots and then reassemble it.
 photo 27 Promate Barracuda strap P1210242.jpg

Before unsheathing the knife for the first time.
 photo 28 Promate Barracuda sheathed P1210247.jpg

Inside the sheath the blade is wrapped in plastic.
 photo 29 Promate Barracuda unsheathed P1210251.jpg

With the knife out, you can see the ambidextrous retention clip.
 photo 30 Promate Barracuda sheath P1210254.jpg

The retention clip is a sprung plate with a catch in the centre and a release button each side.
 photo 31 Promate Barracuda clip P1210257.jpg

A quick look at the back of the sheath.
 photo 32 Promate Barracuda sheath back P1210262.jpg

A fully featured blade made of titanium which has a cutting hook, plain edge, prying blunt tip, smaller plain edge leading into a section of large serrations.
 photo 33 Promate Barracuda angle P1210272.jpg

Clearly marked as being made of titanium.
 photo 34 Promate Barracuda titanium P1210274.jpg

A cutting hook is included near the handle.
 photo 35 Promate Barracuda hook P1210280.jpg

The blunt tip is shaped nicely for prying, tapered but not too thin at the end.
 photo 36 Promate Barracuda blunt P1210284.jpg

Contoured more heavily than any of the other handles, the Barracuda provides excellent grip in all conditions.
 photo 37 Promate Barracuda handle P1210287.jpg

Just at the guard area is the indentation that the retention clip holds on to.
 photo 38 Promate Barracuda catch P1210289.jpg

The back of the blade reveals that the serrations are cut with a single bevel, but the plain edges are double bevelled.
 photo 39 Promate Barracuda blade back P1210293.jpg

Nicely cut, the serrations are larger than any others I’ve used.
 photo 41 Promate Barracuda serration P1210306.jpg

For scale, I take XL size gloves.
 photo 42 Promate Barracuda in hand P1210311.jpg

The butt has a large hammer striking surface. This is made of Titanium, so is not up to very heavy work.
 photo 43 Promate Barracuda hammer P1210314.jpg

Though it doesn’t need any cleaning for corrosion prevention, the Barracuda does fully disassemble.
 photo 44 Promate Barracuda apart P1210335.jpg

As mentioned earlier, the straps need to be threaded through the loops before fitting the quick release buckles.
 photo 45 Promate Barracuda straps P1210340.jpg

Fully assembled and ready for work.
 photo 46 Promate Barracuda straps P1210361.jpg

A few more details of the KF593 Ti:

This is a knife which has had a little more exposure than most and you might recognise it as it was featured in a few episodes of Bear Grylls ‘Man vs Wild’. It is also known unofficially as the Promate ‘Scuba’ Knife, but officially only as the KF593. There is a blunt tip version as well.

The KF593’s box.
 photo 47 Promate scuba box P1210371.jpg

Inside the box the knife comes wrapped in plastic. Also include are two rubber straps.
 photo 48 Promate scuba contents P1210373.jpg

With the wrapping off. There is a warning card included regarding care for the knife, however, this advice proved unnecessary.
 photo 49 Promate scuba contents P1210380.jpg

The KF593 fresh out of the box.
 photo 50 Promate scuba unsheathed P1210384.jpg

One of the great features of the KF593 is the retention system of the sheath. There is a sprung plate with two release buttons and a catch.
 photo 51 Promate scuba sheath lock P1210396.jpg

Looking at the back of the sheath, you can see the lower strap loop serves as a drainage hole. there is also a plastic spring which pushes against the blade when it is in the sheath the prevent rattling.
 photo 52 Promate scuba sheath back P1210403.jpg

This knife has alternative colour options for the handle. The orange part of the handle can be grey or blue.
 photo 53 Promate scuba angle P1210404.jpg

In case you forget, this is a titanium blade. Being a dive knife there is a line cutter hook.
 photo 54 Promate scuba hook P1210409.jpg

An unusual ‘reverse’ set of serrations are on the blade spine.
 photo 55 Promate scuba serrations P1210416.jpg

The full tang protrudes through the handle and provides a narrow hammer.
 photo 56 Promate scuba hammer P1210422.jpg

As supplied, the factor edge looks quite coarse, but cuts well enough.
 photo 57 Promate scuba edge P1210426.jpg

A nice mid-sized knife. (I take XL size gloves.)
 photo 58 Promate scuba in hand P1210431.jpg

The coloured rubber insert gives a good amount of grip.
 photo 59 Promate scuba handle P1210434.jpg

Rather than quick release buckles, this knife uses belt buckle type fastenings. Note that the holes in the strap are actually filled in. The first time you use any of them you need to push the buckle prong through the rubber in the hole.
 photo 60 Promate scuba strap P1210442.jpg

These straps are very quick and easy to set up and use.
 photo 61 Promate scuba with straps P1210444.jpg

A few more details of the KF505 Blunt:

And onto the last one of the Promate knives, the steel bladed KF505.
 photo 62 Promate steel box P1210448.jpg

In the box is the sheathed knife, rubber straps, care instructions and disassembly instructions.
 photo 63 Promate steel box contents P1210458.jpg

The clear sheath is an option for this knife.
 photo 64 Promate steel sheath back P1210461.jpg

A box-fresh KF505.
 photo 65 Promate steel unsheathed P1210464.jpg

Compared to the titanium knives a different sheath retention system used. A single release button on the front of the sheath is connected to a catch at the rear.
 photo 66 Promate steel sheath lock P1210467.jpg

Before moving onto some details let’s look at both sides of the blade.
 photo 67 Promate steel angle P1210478.jpg

The other side of the blade.
 photo 68 Promate steel angle P1210485.jpg

An unspecified stainless steel is used for the guard. Check the corrosion results later.
 photo 69 Promate steel guard P1210487.jpg

The serrations are cut with a single bevel.
 photo 72 Promate steel serrations P1210492.jpg

The use of a single bevel is clear when looking at the other side.
 photo 73 Promate steel serration back P1210496.jpg

A line cutting hook is ground into the blade near the handle. Note the steel designation on the blade – Stainless Steel 420 J2.
 photo 74 Promate steel hook P1210498.jpg

This knife uses a one-piece rubber handle.
 photo 75 Promate steel handle P1210509.jpg

The tang nut acts as a hammer.
 photo 76 Promate steel hammer P1210513.jpg

Starting to disassemble the knife by taking the tang nut off.
 photo 77 Promate steel hammer off P1210517.jpg

And fully disassembled.
 photo 78 Promate steel apart P1210528.jpg

The rubber straps have standard belt buckle type fixings.
 photo 79 Promate steel strap P1210531.jpg

This design of strap make it very quick and easy to get everything put together ready for use.
 photo 80 Promate steel with straps P1210534.jpg

Like the previous model this is a medium sized knife.
 photo 82 Promate steel in hand P1210541.jpg

What are they like to use?

With several very different offerings from Promate, the cutting results were varied and also not as I expected. The best performer in the cutting tests was actually the Seal folder with Ti blade. This maintenance-free small titanium bladed folder makes a fantastic backup knife. The other knives were mainly let down in the cutting tests by the factory edges, and are more capable given a bit of work getting a good edge.
The biggest surprise was the performance of the dedicated line cutter; using only a standard steel utility blade as the cutting edge, the corrosion testing really took its toll on this (details to follow). With a new blade, initial tests were that this was a very good cutter, so if you can find stainless utility blades they would be a better option.
See the Dive Knives 2016 – Mega Test Review for more information on the cutting test results.

Though a really excellent cutter, the Seal knife had a small issue that was easily fixed, but one worth being aware of.
The sharp eyed might have spotted that when looking at the ‘H’ (where the blade spine and lock bar touch), the lock bar is slightly raised. This gave me concern over how well the lock would function. Proven correct, I found the lock failed under mild pressure to close the blade.
 photo 22 Promate Ti Folder H P1210213.jpg

Taking a closer look at the locking surfaces, these appeared to be raw pressings so the fit was not good, and the blade tang hook was not catching the lock bar well. There is a simple fix for that….
 photo 22 Promate Ti Folder lock P1210364.jpg

Without having to take the knife apart, the blade tang hook can be cleaned up with a file (and the Ti files easily) to give a much better flat locking surface. Be careful not to go at this too much as taking more material than necessary will result in a blade that has play in the locked position. File a bit then test, and repeat. Once corrected, the locked blade was solid and the result was worth having to do this.
 photo 22 Promate Ti Folder lock P1210377.jpg

Earlier I mentioned the line cutter having disappointing cutting results, well this is why – Oh dear! The corrosion testing certainly hit the weak spot of this design – standard carbon steel blades. Cheap and easy to replace, but the rust starts as soon as it gets wet.
 photo 84 Promate line cutter corrosion P1230148.jpg

The corrosion tests threw up a surprise with the stainless steel knife. Typically, non-cutting stainless parts have a higher grade of stain resistance (with lower cutting ability), but in this case the worse corrosion was to the guard (though the hammer pommel was completely free of corrosion). The blade had a light frosting, but the guard was heavily corroded. After a cleanup, the guard was found to have deep pitting, and the clean-up (using a soak in cider vinegar) actually etched the guard heavily while making the blade nice and shiny.
 photo 85 Promate steel corrosion P1230009.jpg

The blade itself was relatively untouched and the frosting cleaned off with vinegar.
 photo 86 Promate steel corrosion P1230013.jpg

Ergonomics of the Promate knives is excellent, with easy to use, and secure, sheath retention along with great straps.

Folders are a contentious subject for diving, as the action of opening can be a make or break moment for the diver. The opening hole in the Seal folder is a little small, and being experienced in one-handed-opening (OHO) I did find this to be perfectly usable even with gloves, but with tired, cold hands and very thick gloves I suspect it will become increasingly difficult. There is also the exposed cutting hook to consider. This hook was actually a very poor cutter as it was not very sharp as supplied; with it being exposed, this lack of sharpness is actually a benefit. The Seal’s blade is worth carrying this knife for, with very good cutting ability and excellent serrations.

Overall it is clear these Promate knives are designed very well for divers, and the added bonus of zero corrosion on the titanium blades make them well worth considering.

Review Summary

The views expressed in this summary table are from the point of view of the reviewer’s personal use. I am not a member of the armed forces and cannot comment on its use beyond a cutting tool or field/hunting knife.

Something that might be a ‘pro’ for one user can be a ‘con’ for another, so the comments are categorised based on my requirements. You should consider all points and if they could be beneficial to you.

_______________________________________________ _______________________________________________
Things I like What doesn’t work so well for me
_______________________________________________ _______________________________________________
Titanium blades require no post-dive cleanup. The steel knife and cutter suffered corrosion.
Excellent blade retention. Factory edges not very good.
Comfortable leg straps. Serrations are too coarse for smaller ropes.
Handle design provides a very secure grip.
Sheaths are ambidextrous.

 photo 83 Promate line up P1210543v2.jpg

 

Discussing the Review:

Please feel free to add comments to the review, but the ideal place to freely discuss these reviews is on a forum. If you started reading the shorter forum version of the review, but followed the link this full exclusive review, please return to that forum to discuss the review there.
If you read the review entirely on Tactical Reviews, please consider one of the following to join in any discussion.

EdgeMatters – Sponsored Reviews (UK based Forum for Knife Makers and Collectors)

BladeForums – Knife Reviews (US based Forum for Knife Discussion)

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Knife Review: Spyderco Assist Salt (Dive Knives 2016 – Detail Review)

This review provides further details for the Spyderco Assist Salt which could not be included in the Dive Knives 2016 – Mega Test Review

Not strictly a diving knife, thanks to the Assist model’s reputation as a rescue knife and the use of specialist rustless H1 steel in the ‘Salt’ edition, it has been adopted by many divers as an underwater rescue knife.

 photo Dive Knives underwater P1000872.jpg

The Blade and Handle Geometry:

Most knife specifications have a basic description of the blade geometry, but in this section I will be taking a more detailed look at geometry and balance.

Using a set of gauges and precision measuring equipment including a Vernier protractor, callipers, fixed radius gauges and the unique Arc Master adjustable radius gauge (the one that looks like a crossbow).
 photo Knife measuring P1180483.jpg

These measurements have been tabulated and are presented along with other blades.

Key aspects such as the primary bevel angle, grind type, blade depth, blade thickness, length, weight are detailed, along with balance information.

The ‘Balance relative to the front of the handle’ tells you if the knife will feel front heavy, or if the weight is in your hand (a positive value means the weight is forward of the front of the handle). The ‘Balance relative to the centre of the handle’ indicates how close to a ‘neutral balance’ the knife has in the hand.

In the case of full convex grinds the approximate centre of the grind is used for the primary bevel angle estimate.

The measurements are presented alongside some of the other knives from the Dive Knives 2016 – Mega Test Review

 photo Dive Knives Parameters 1 of 3.jpg

A few more details:

The Assist Salt arrives in Spyderco’s standard box.
 photo 01 Salt Assist boxed P1180225.jpg

An instantly recognisable design, but now in a bright yellow FRN and with H1 proudly shown on the blade. You will notice the Assist model’s ‘cobra hood’ over the thumb hole is not present on the Salt version.
 photo 02 Salt Assist unboxed P1180232.jpg

Spyderco’s very grippy FRM scale pattern surrounds the model and logo.
 photo 03 Salt Assist detail P1180239.jpg

And why not? There is a whistle moulded into the handle.
 photo 04 Salt Assist whistle P1180240.jpg

A Spyderco wire clip is used. This can be fitted to either side of the handle.
 photo 05 Salt Assist clip side P1180249.jpg

The ends of the wire clip are held in place under a special hollow bolt that also provides the lanyard hole.
 photo 06 Salt Assist clip fastning P1180251.jpg

At first it looks like the cutout in the lock bar is misaligned, but….
 photo 07 Salt Assist lock bar P1180256.jpg

…no, this is one of the Spyderco details where due to the pivoting action of the lock bar, the cutout does line up once pressed in to release the lock (or due to opening the blade).
 photo 08 Salt Assist lock bar 2 P1180259.jpg

The Assist uses a mostly serrated edge (80%), but with a small section of plain edge for detailed tasks. The main cutting power of the blade is in those SpyderEdge serrations.
 photo 09 Salt Assist part open P1180260.jpg

With well formed finger grooves and the textured FRN handle, the Assist Salt is not short on grip.
 photo 10 Salt Assist open P1180265.jpg

Yes, that is H1 steel.
 photo 11 Salt Assist H1 P1180270.jpg

For those not familiar with the Assist model, we’ll come back to the grooves in the blade spine.
 photo 12 Salt Assist blade P1180274.jpg

Recessed into the butt of the handle, there is a point that looks like a glass breaker.
 photo 13 Salt Assist breaker P1180289.jpg

With the blade closed, if you give it a squeeze, the glass breaker point comes out of the handle ready to use.
 photo 14 Salt Assist breaker out P1180291.jpg

Inside the handle where the blade tip sits, there is a small sprung block which has the glass breaker in it.
 photo 17 Salt Assist breaker push P1180322.jpg

The rounded end of the blade presses into this block and pushes the glass breaker out for use. Very neat design.
 photo 18 Salt Assist breaker pusher P1180325.jpg

What it is like to use?

Being a folder, for use as a dive knife, it is important that the Assist is a good size as this makes it easy to handle with, and without, gloves.

Actually in terms of easy handling, this is where I was slightly disappointed with the Salt version, as for some reason Spyderco decided to do away with the ‘cobra hood’ over the thumb hole. The thumb hole is still big enough to make opening easy enough, but that cobra hood would have made all the difference when using wet gloves with cold hands, just giving you more to get hold of.

 photo Dive Knives underwater P1000872.jpg

With the claims about H1 steel, I was particularly interested to see the corrosion test results. What did surprise me was what looked like a failure in this regard. However looking much closer, the apparent corrosion is actually the black writing on the blade which has mostly disintegrated, but where the black ‘1’ was, it has made it look like the blade has rusted. However this can be cleaned off leaving just the H1 steel. It might be better for Spyderco to use a different ‘ink’ for the writing, or none at all, to avoid this blemish on the otherwise unmarked H1 steel.
 photo Spyderco corrosion P1220990.jpg

The distinctive blade is a good size (I take XL size gloves) as can be seen here. This is ideal as you have plenty of edge to work with combined with the safety of the blunt tip to prevent stabbing yourself (or others).
 photo 19 Salt Assist in hand P1180341.jpg

To give an idea of scale, here it is next to the Fällkniven F1 and a Spyderco UK Pen Knife.
 photo 16 Salt Assist size P1180310.jpg

We have already seen the hidden glass breaker and how the finger grooves in the blade spine are used to access this, but there is another design feature that these finger grooves provide. The Assist can be used as a type of shears where the material to be cut is placed under the folding blade and the blade then squeezed shut to complete the cut. In this arrangement, you are carrying out a push cut with a serrated blade, when the serrations work best in a sawing motion. Personally, despite the very sharp blade, I found this to not work well on wet rope, in fact a normal cut worked far better, so for me the jury is out on that feature.

Unsurprisingly the SpyderEdge was an excellent cutter, and the H1 steel held up well. See the Dive Knives 2016 – Mega Test Review for more information on the cutting test results where the Assist achieved the second highest score.

Personally for a ‘working’ diving knife I prefer a fixed blade, but as a backup/release knife, the Assist gives me real confidence when carrying it. Requiring little to no care or maintenance, the Assist Salt is just ready and waiting for when you need it.

Review Summary

The views expressed in this summary table are from the point of view of the reviewer’s personal use. I am not a member of the armed forces and cannot comment on its use beyond a cutting tool or field/hunting knife.

Something that might be a ‘pro’ for one user can be a ‘con’ for another, so the comments are categorised based on my requirements. You should consider all points and if they could be beneficial to you.

_______________________________________________ _______________________________________________
Things I like What doesn’t work so well for me
_______________________________________________ _______________________________________________
Proven Escape Knife Design. The Assist ‘Cobra Hood’ is not on the Salt version.
H1 ‘Rustless’ Steel. Blade marking corrode (even though the steel doesn’t).
Built-In Signal Whistle
Built-In Glass Breaker.
Excellent grip.

 

Discussing the Review:

Please feel free to add comments to the review, but the ideal place to freely discuss these reviews is on a forum. If you started reading the shorter forum version of the review, but followed the link this full exclusive review, please return to that forum to discuss the review there.
If you read the review entirely on Tactical Reviews, please consider one of the following to join in any discussion.

EdgeMatters – Sponsored Reviews (UK based Forum for Knife Makers and Collectors)

BladeForums – Knife Reviews (US based Forum for Knife Discussion)

CandlePowerForums – Knife Reviews Section (Largest and Friendliest Flashlight Community Forum)

Knife Review: Benchmade 112S H2O (Dive Knives 2016 – Detail Review)

This review provides further details for the Benchmade 112S H2O which could not be included in the Dive Knives 2016 – Mega Test Review

 photo 10 H2O angle P1200651.jpg

The Blade and Handle Geometry:

Most knife specifications have a basic description of the blade geometry, but in this section I will be taking a more detailed look at geometry and balance.

Using a set of gauges and precision measuring equipment including a Vernier protractor, callipers, fixed radius gauges and the unique Arc Master adjustable radius gauge (the one that looks like a crossbow).
 photo Knife measuring P1180483.jpg

These measurements have been tabulated and are presented along with other blades.

Key aspects such as the primary bevel angle, grind type, blade depth, blade thickness, length, weight are detailed, along with balance information.

The ‘Balance relative to the front of the handle’ tells you if the knife will feel front heavy, or if the weight is in your hand (a positive value means the weight is forward of the front of the handle). The ‘Balance relative to the centre of the handle’ indicates how close to a ‘neutral balance’ the knife has in the hand.

In the case of full convex grinds the approximate centre of the grind is used for the primary bevel angle estimate.

The measurements are presented alongside some of the other knives from the Dive Knives 2016 – Mega Test Review

Please note the Benchmade 112S is incorrectly named the 112B in the table.
 photo Dive Knives Parameters 1 of 3.jpg

A few more details:

Benchmade’s nicely presented box.
 photo 01 H2O boxed P1200611.jpg

Taking the lid off the box gives your first view of the sheathed model 112S H20 diving knife.
 photo 02 H2O box open P1200616.jpg

Included are the sheathed knife, a single rubber strap and a leaflet.
 photo 03 H2O box contents P1200618.jpg

The strap, which can be used for a calf strap or arm strap has a quick release buckle.
 photo 04 H2O strap P1200622.jpg

A closer look at the plastic buckle and the rubber strap’s adjustable and fixed ends.
 photo 05 H2O strap buckle P1200628.jpg

The sheathed 112S H2O is a very neat package.
 photo 06 H2O sheathed P1200632.jpg

There is an essential drainage hole at the bottom of the sheath.
 photo 07 H2O drainage P1200636.jpg

On one side of the sheath is a very neat and functional release lever which holds and release the knife.
 photo 08 H2O retention P1200641.jpg

Looking in a bit closer you can see the metal pivot made of 316 Stainless Steel and hidden inside is a zinc-plated music wire spring.
 photo 09 H2O retention close P1200643.jpg

And here it is, the 112S H2O knife.
 photo 22 H2O angle P1200687.jpg

Featuring a blunt tip designed for safety and prying, there is a plain edge near the tip and a serrated edge closer to the handle.
 photo 11 H2O blade tip P1200653.jpg

Two sizes of scallop are used for the serrations.
 photo 12 H2O serrations P1200655.jpg

The plunge line is nicely radiused to avoid stress concentrators, especially important as the blade is designed to pry.
 photo 13 H2O plunge P1200659.jpg

A first finger indentation combined with a grippy rubber handle, makes the 112S very sure in the hand.
 photo 14 H2O handle P1200661.jpg

Surprisingly missing from some dive knives, the 112S has a lanyard hole.
 photo 15 H2O lanyard P1200663.jpg

On the spine is a small protrusion; it is this that the retaining clip locks onto to keep it secure in the sheath.
 photo 16 H2O retention hook P1200667.jpg

Part of what makes the 112S look strange, but yet which gives it its excellent cutting power is the chisel grind used for the main edges. This is the back of the blade and it is essentially just flat steel.
 photo 17 H2O blade back P1200673.jpg

The rear of the serrations.
 photo 18 H2O serration back P1200676.jpg

And of the plain edge.
 photo 19 H2O edge back P1200677.jpg

Also included in the blade design is a line cutter hook. This too is a chisel grind and is cut the opposite way to the main edges (back to front instead of front to back).
 photo 20 H2O cutting hook P1200680.jpg

Looking along the blade from the flat side.
 photo 21 H2O reverse anlge P1200684.jpg

What it is like to use?

Coming from a well respected knife manufacturer, the 112S had a lot to live up to. One of the stranger looking knives, it might not be one which you drool over and ‘must have’. However there is purpose behind every design detail, and its cutting test results speak for themselves. Only shears equalled the cutting score of the 112S, that is quite some achievement. See the Dive Knives 2016 – Mega Test Review for more information.

Another key feature of the 112S is the sheath and the retention system. As long as you mount the sheath so that your hand falls onto the handle and your thumb onto the release lever, the drawing of the knife becomes completely natural. Your thumb presses the lever as you grip the knife and the knife can be easily withdrawn. I have found that if pulling on the knife too early, the release lever can’t ‘let go’ of the knife and you have to push the knife back into the sheath to allow it to release the lock. I particularly like that there is a slight friction fit of the knife into the sheath, so even with the lock released, it doesn’t just fall out.

For a good knife steel (N680), the 112S performed very well in the corrosion testing. Here is the raw result of this testing, but actually a lot of this rubbed off with a cloth, leaving only really the outer ring of the corrosion. Less easy to see, there is some corrsion near the handle rubber, but overall for what really constitutes complete neglect, the 112S did not suffer any significant corrosion.
 photo Benchmade corrosion P1220994.jpg

One concern I had was about only a single strap being provided, and this was for two reasons. Firstly was comfort of fit – with two straps you don’t need either to be too tight, but secondly and perhaps more importantly, in case a strap snapped, was cut, or became snagged on something, once that single strap has failed you could lose the knife.

 photo 23 H2O with strap P1220134.jpg

However, my concerns over comfort proved not to be realised at all, and the strap is a good quality so felt secure enough. As long as you check its condition regularly it should be reliable.

In the Dive Knives 2016 – Mega Test Review I did express a preference for one of the knives on test, but that was in relation to a general purpose backup knife. If I were expecting a lot of cutting work, then the Benchmade 112S would jump right up there and would be my pick of the bunch as a quality cutting and prying tool.

Review Summary

The views expressed in this summary table are from the point of view of the reviewer’s personal use. I am not a member of the armed forces and cannot comment on its use beyond a cutting tool or field/hunting knife.

Something that might be a ‘pro’ for one user can be a ‘con’ for another, so the comments are categorised based on my requirements. You should consider all points and if they could be beneficial to you.

_______________________________________________ _______________________________________________
Things I like What doesn’t work so well for me
_______________________________________________ _______________________________________________
Excellent cutting performance. Only a single leg strap.
Great ergonomics for knife and sheath. Slight concern over the corrosion resistance of the ‘music wire’ spring used for the sheath lock.
Sheath is easy to use and secure.
Strong prying tip.
Very good corrosion resistance.

 photo H2O feature P1200700.jpg

 

Discussing the Review:

Please feel free to add comments to the review, but the ideal place to freely discuss these reviews is on a forum. If you started reading the shorter forum version of the review, but followed the link this full exclusive review, please return to that forum to discuss the review there.
If you read the review entirely on Tactical Reviews, please consider one of the following to join in any discussion.

EdgeMatters – Sponsored Reviews (UK based Forum for Knife Makers and Collectors)

BladeForums – Knife Reviews (US based Forum for Knife Discussion)

CandlePowerForums – Knife Reviews Section (Largest and Friendliest Flashlight Community Forum)

Dive Knives 2016 – Mega Test Review

Knife blades and seawater are usually something I do my best to keep apart, but when diving a knife must survive some of the most hostile conditions and its performance can be a matter of life and death.

This Mega Test Review brings together twelve knives from five leading knife brands and puts them to the test in real world conditions covering geometry, corrosion resistance, ergonomics and wet cutting performance, as well as comparing steel to titanium, serrations to plain edges, fixed blades to folders and dedicated line cutters to standard knife blades.

The selection of knives was specifically put together to show as many different aspects as possible and considerations which could be applied to knives not in this review.

 photo 03 Dive Knives Group 3 P1220979.jpg

Here we go!

The contenders:

First up, the contenders one by one. Due to the sheer size of the Mega Review and the testing, I’ve had to create are additional supporting reviews, knife brand by knife brand, concentrating on some more specific details of each knife. These are now all completed and can be found through the following links:

Benchmade 122S H2O – REVIEW ONLINE
Spyderco Assist Salt – REVIEW ONLINE
Promate Barracuda Blunt, KF593 Ti, KF090 Seal Folder Ti, KF505 Blunt, KF001 Line Cutter – REVIEW ONLINE
Whitby DK9, DK11, DK511/14 – REVIEW ONLINE
Cressi Giant Knife, Alligator – REVIEW ONLINE

These are the ones that arrived before a diving trip to the Ionian Sea.
 photo 01 Dive Knives Group 1 P1210099.jpg

The last minute entries which unfortunately didn’t get to travel as much.
 photo 02 Dive Knives Group 2 P1220175.jpg

The following photos are of each knife tested.

Benchmade 122S H2O

Correction: in the data tables later in the review the 112S is incorrectly named the 112B.
The H2O fixed was originally developed for an elite military program. The knife features a blunt tip, opposing bevel for torsional strength and an integrated cutting hook.
Blade Steel: N680 (57-59 HRC)
 photo 20 Dive Knife 01 P1200650.jpg

Spyderco Assist Salt

Not specifically a dive knife, the Assist Salt combines the multi-functional versatility of the Assist model with the rustproof qualities of H-1 steel. The defining feature of the Assist Salt is its H-1 steel blade and lock bar. This material uses nitrogen instead of carbon to create a steel that is tough and completely immune to corrosion.
 photo 21 Dive Knife 02 P1180267.jpg

Promate Barracuda Blunt

Made for the professional diver, the Barracuda has a Titanium blade and Titanium hammer on handle bottom. There are quick-release adjustable straps, and though the knife is easy to disassemble it requires little or no maintenance.
 photo 22 Dive Knife 03 P1210272.jpg

Promate KF593 Ti

Designed by scuba diver’s for scuba divers, the light weight Titanium blade with easy-grip rubber molded handle requires little or no maintenance. The full tang protrudes through the handle providing a narrow Titanium hammer on the handle bottom.
 photo 23 Dive Knife 04 P1210404.jpg

Promate KF090 Seal Folder Ti

Light weight Titanium bladed folder requiring little or no maintenance with an adjustable lanyard for easy carrying.
 photo 24 Dive Knife 05 P1210184.jpg

Promate KF505 Blunt

Using a 420 stainless steel blade there is a hammer on the handle bottom and easy-grip rubber handle. The KF505 is easy to disassemble for cleaning and maintenance.
 photo 25 Dive Knife 06 P1210485.jpg

Promate KF001 Line Cutter

Heavy-duty line cutter with easy hold handle. Disassembles to replace the blade and includes 2 replacement blades (standard utility knife blades).
 photo 26 Dive Knife 07 P1210140.jpg

Whitby DK9

2.75” Stainless steel double-edged serrated/plain blade and Stainless steel handle.
 photo 27 Dive Knife 08 P1210602.jpg

Whitby DK11

The Whitby Divers’ Knife DK11 features a double-edged blade with one edge being serrated and the other is a fine edge. In addition to its multi-purpose blade, the Whitby Divers’ Knife DK11 features a hammer hilt, situated within the rubber handle.
 photo 28 Dive Knife 09 P1210675.jpg

Whitby DK511/14

This Diver’s Knife has a 6.25-inch stainless blade and an overall length of 11 inches. The handle of the Whitby Diver’s Knife DK511/14 is contoured moulded black plastic and the knife is supplied with a plastic sheath with arm/leg straps. A big, traditional, diving knife design.
 photo 29 Dive Knife 10 P1210739.jpg

Cressi Giant Knife

This knife has large dimensions that make it particularly effective during use. Perfect as a work tool or for particularly intensive use. Featuring a Japanese 420 Stainless Steel blade with black coating treatment for corrosion resistance.
 photo 30 Dive Knife 11 P1220318.jpg

Cressi Alligator

The CRESSI Alligator is a unique tool offering the function of a Knife and Scissors. The 420-Stainless Steel Blade has a Straight and Serrated Edge plus a cutting hook and shears. It comes with a Hose Mount Sheath.
 photo 31 Dive Knife 12 P1220271.jpg

The Blade and Handle Geometry:

Most knife specifications have a basic description of the blade geometry, but in this section I will be taking a more detailed look at geometry and balance.

Using a set of gauges and precision measuring equipment including a Vernier protractor, callipers, fixed radius gauges and the unique Arc Master adjustable radius gauge (the one that looks like a crossbow).
 photo Knife measuring P1180483.jpg

Key aspects such as the primary bevel angle, grind type, blade depth, blade thickness, length, weight are detailed, along with balance information.

The ‘Balance relative to the front of the handle’ tells you if the knife will feel front heavy, or if the weight is in your hand (a positive value means the weight is forward of the front of the handle). The ‘Balance relative to the centre of the handle’ indicates how close to a ‘neutral balance’ the knife has in the hand.

In the case of full convex grinds the approximate centre of the grind is used for the primary bevel angle estimate.

These measurements have been tabulated and are presented in smaller bite size chunks and also in one overall table.
Important – there are critical performance indicators here, in particular the edge angle of the plain edges, serrated edges and cutting hook edges. A larger angle reduces the cutting ability significantly.

The first four knives.
Please note the Benchmade 112S is incorrectly named the 112B in the tables.
 photo Dive Knives Parameters 1 of 3.jpg

The next four.
 photo Dive Knives Parameters 2 of 3.jpg

And the final four.
 photo Dive Knives Parameters 3 of 3.jpg

For a direct comparison this is the entire table. You might need to zoom in or save the image and view it separately to see all the details.
 photo Dive Knives Parameters All.jpg

Corrosion tests:

In this Mega Test Review you get an insight into the full process I carry out for all my reviews, but in particular here we have very specific stages. You have already seen some of the studio photography, and technical testing (the parameters), and now we move onto a critical part of the performance testing preparation.

I have chosen to run the corrosion testing before any measured cutting tests, for the specific reason that you will not normally take a dive knife out of the box and immediately ‘need’ to cut ropes and line with it. It is far more likely you will carry it on a few dives before you really need it to cut anything or free yourself from an entanglement. So the idea here is to look at the cutting performance AFTER the corrosion tests, as if the cutting edge is actually damaged by corrosion, it may well fail you when you really need it.

As it turns out, the initial testing site in the Ionian sea, is one of the saltiest seas in the world with a PSU measurement of 38. This is where we digress into the subject of salinity, but I’ll just mention a few key points in the preparation of the corrosion testing.

The chart below (from World Ocean Atlas 2005 data) shows how the salinity of the sea varies across the globe.

 photo World Ocean Atlas 2005 annual_clim-800.jpg

The units are shown in PSU which stands for Practical Salinity Unit. The PSU is derived from the ppt (parts per thousand) value of the salts dissolved in a kilogram of water. On average, seawater in the world’s oceans has a salinity of about 3.5% (35 g/L, 35 ppt, or 599 mM). This means that every kilogram (roughly one litre by volume) of seawater has approximately 35 grams (1.2 oz) of dissolved salts (predominantly sodium chloride NaCl). Average density at the surface is 1.025 kg/l. Seawater is denser than both fresh water and pure water (density 1.0 kg/l at 4 °C (39 °F)) because the dissolved salts increase the mass by a larger proportion than the volume.

And breath….

So, due to not receiving all the test candidates before the trip, I needed to replicate the conditions of the initial corrosion tests to keep everything consistent. What I needed was seawater with the same salinity as the starting conditions (also to then be used for the wet cutting tests). This is not as simple as taking tap water and adding salt to it, as the chlorine in the water affects corrosion, and the salts in seawater are not just NaCl. So as a starting point I went to collect some local seawater (from the English channel). This typically has a salinity of 35 PSU, but I was collecting from a beach where rainwater runoff would likely be diluting the salinity.

 photo Salinity Test collecting.jpg

Fortunately thanks to people keeping fish as pets, there are a lot of easy tools for checking this, and the simplest being a hydrometer to measure specific gravity. The one I have used is for owners of salt-water fish and has a green section indicating the correct salinity range. As you can see here, the hydrometer is showing the salinity is at the lower end of the range (as not much green is showing). Reading off the specific gravity, and crucially the temperature as well, a temperature/specific gravity chart was checked showing that this seawater was measured as 29 g/l or 29 PSU.

 photo Salinity Test.jpg

This meant that to get to 38PSU I needed to increase the salinity. Fortunately pet shops sell ‘Aquarium Salt’ (which is basically dried seawater and contains all the salts in seawater). All I had to do was add a further 9g/Kg of aquarium salt to bring it to 38g/l. After adding the additional aquarium salt and re-measuring, the salinity was indeed at 38PSU.

Now I had suitably salty seawater, I proceeded to replicate the series of immersion tests carried out over the initial two week test period. This was based on the example of a diver spending around 2 hours in the water each day and then taking their gear out and letting the knife drip dry until the next day (or not quite dry). The knives would have a mixed exposure to air and seawater (which as it dries becomes a much higher salinity). Of course the original tests were carried out in much higher temperatures, so an aquarium heater was used to heat the seawater to match the original temperature.

After the full set of corrosion testing, the knives were soaked in freshwater, then the water was changed for a further soak to bring out the salts. The knives were then dried and inspected.

This post from my Instagram feed shows the results in a ranked order. It must be noted that some results were very close, so the top 5 had virtually nothing between them.

In the final results table, each knife has been given a score out of 25 for its corrosion resistance, so you can find the exact rating in that table, but as a brief description in ranking order:

The Promate Titanium knives were spotless (including the sheaths), the Spyderco had only a single spot due to the black text on the blade, and the Cressi Giant was the only standard stainless steel knife to have no visible corrosion. The Benchmade has some light staining, with the Cressi alligator having only light signs of rust. Then things started to ramp up in corrosion. The Promate stainless knife actually had quite heavy corrosion on the guard but very little on the blade. The Whitby knives all had blade and edge rusting. Worst of all was the Promate line cutter, but this used only standard non-stainless utility blades, so no surprise there. These utility blades can of course be easily and cheaply changed.
 photo 04 Dive Knives Group corrosion test IMG_20160903_234909.jpg

A look at serrations and edge geometry:

There are a few aspects which are important to understand which relate to the design of the serrations and the edge geometry, and which affect cutting performance drastically. Though this is a slight digression to talk about the subject, it will help to explain the cutting test results.

You might have skipped over the ‘The Blade and Handle Geometry’ section, but it is worth noting the details in that table. The edge angle used will give a mixture of ‘sharpness’ and ‘durability’, and the smaller the angle the sharper but less durable it is. In the case of the dive knives here, ‘Chisel’ vs ‘Standard’ grinds have a huge effect for the plain and serrated edges, as well as the cutting hooks.

To visualise this, here is diagram of a Single bevel (Chisel grind) and Double bevel (Standard Grind) edge, and both these edges cutting into some material. The Chisel Grind has been sharpened at 22° and as it is a single bevel edge, the total ‘included’ angle is also 22° (22° + 0°). A Standard double bevel edge also sharpened at 22° has an ‘included’ angle of 44° (22° + 22°) and though still sharp, this edge has to part the material much more as it cuts resulting in a much higher cutting force being required to complete the cut.
 photo EdgeAngle.jpg

After looking at the edge angle and its effect on cutting force we also need to consider how the size of serrations can make another huge difference in how well the edge cuts.

Let’s start by looking at two of the blades on test, one with large scallops for the serrations, and one with two sizes of scallop that are much smaller than the first. Between them are a series of different size rope cross-sections.
 photo Dive Serration 2 -125.jpg

Coming from the Latin word ‘serra’ meaning saw, for a serrated edge to start cutting it needs to move over the surface of the rope to allow the teeth to start working, but if the serrations are too large, then instead of moving over the surface and sawing into it, the rope can stick in a single serration making the sawing action difficult. Here we can see how the four smallest rope sizes will catch in these large serrations and only once the rope size increases can the serrations teeth start to work on the rope surface.
 photo Dive Serration 3 -125.jpg

A blade with smaller serrations is able to ride over the surface of much smaller ropes and allowing the sawing action to work. Only the very smallest rope here will catch in the teeth, with the second smallest the smaller teeth can get to work and the cut will progress.
 photo Dive Serration 4 -125.jpg

Smaller serrations are definitely more versatile, but are harder to maintain, so you need to find the balance that works for you. In the cutting tests, the size of serrations does have an impact on the results.

Cutting tests:

The testing in this group review is actually my first direct cutting comparison between steel and titanium blades. I had thought there would be a big difference between these blade materials, but in the experimental cutting tests, the Titanium Vs Steel aspect was not directly evident.

 photo 06 Dive Knives Group Ti vs Steel IMG_20160725_190252.jpg

If more extended testing had been carried out, where edge durability starts to come into play, then steel would begin to take the lead, but starting with the factory edge and dealing with a reasonable amount of cutting, edge retention was not a factor.

Being a Dive Knife group test, all cutting tests were carried out in seawater with pre-soaked materials. The list of materials to be cut was chosen after consulting active divers to cover the most common cutting scenarios.
To represent discarded and lost fishing hazards the cutting test includes 15lb and 50lb Monofilament plus 15lb and 115lb Dyneema braid (for fishing lines) as well as 2mm Nylon Braid (netting).
3-4mm Nylon Braid represents cave line, 50mm (2″) webbing as if you were having to cut away a BCD, and cable-ties for cutting away items attached to your gear that might be snagged. Lastly a medium 8-10mm rope as this is a very common size.

With the vast majority of my cutting experienced being with dry cutting tasks, the effect of wet cutting on the different materials was actually shocking. Materials that cut so easily when dry became difficult with the lubricating effect of the water. For some fibrous materials there seems to be a strengthening effect as well (which is difficult to explain scientifically), though this might simply be due to the lubrication making them more abrasion resistant. When wet, the materials are more difficult to grip and in the water the entanglement will often be free floating so needs to be gripped to be cut. Altogether this adds up to a challenging cutting experience and one which shows any weaknesses of the tool being used.

Another Instagram feed image which shows some of the cut materials with the knives.
 photo 05 Dive Knives Group cutting test IMG_20160918_155600.jpg

The totals for each knife’s cutting performance are shown in the final full and summary results tables, but here, just the cutting performance of each knife with each material is shown. The score is a 5 for a very easy and clean cut, down to a 0 for a failure to cut the material. A few of the knives were clear leaders in the cutting tests. Remember, this is also with blade edges that have been through the corrosion tests. The Cressi Alligator has two sets of results to allow the knife blade and shears to be directly compared. The shears were top performers in the cutting test, but were also matched by the Benchmade H2O.

 photo Dive Knives Cutting Test Full Results.jpg

What are they like to use?

A much more subjective section as it is difficult to quantitatively score how each knife is to use. We have considerations such as the leg straps, opening and closing a folder, unsheathing and re-sheathing the fixed blades, size and weight, grip and ergonomics. All of these factors needed to be considered with bare hands and diving gloves, and then translated into an ergonomics score.

There is far too much to cover in this group review, so you will need to refer to the individual reviews referenced at the beginning of this article.

When comparing leg straps, the choice of quick release or buckle fastening will come down to a matter of personal preference. I found that as you need to the fix the strap length for the quick release type, that sometimes the fit was not so good (perhaps if changing leg or even just depending on the temperature), so the standard buckle fitting worked better (despite being slower to fit and take off) as the fit was adjusted for each and every dive.
 photo 08 Dive Knives Group wearing promate IMG_20160720_201115.jpg

For the fixed blades, retention methods varied with rubber straps, clips and sprung plates all be used. More information on this will be seen in the individual reviews. On dry land all the knives are easy to unsheathe, but once strapped to you and you are free-floating in water, this changes significantly and shows the strengths and weaknesses of each design. Critically can you access the knife with either hand as your handed hand might be the one that is entangled.

An important consideration is the ease of re-sheathing the knife. This is where you will want to decide if you really need that sharp point or if a blunt tip knife is better.
 photo 09 Dive Knives underwater P1000788.jpg

Once in the hand, how good is the grip.
 photo 11 Dive Knives underwater P1000864.jpg

If choosing a folder, how easy is it to open, especially with gloves. Is it a two handed operation?
 photo 12 Dive Knives underwater P1000872.jpg

A lot of factors and only a score out of 25 to work with. These scores are included in the overall results table.

Overall results:

With so much information to present, unfortunately the only way is with a couple of results tables. There are two tables included here, one is the full results table with detailed cutting test results. This is packed with information and you will need to view the image separately (click on it) to expand it and read all the detailed results.

Please note the Benchmade 112S is incorrectly named the 112B in the tables.
 photo Dive Knives Test Full Results plus grand total.jpg

Taking out the detailed cutting test results makes for a more manageable results table, and here the scores have been put into ranking order with the top scores at the top of the table.

 photo Dive Knives 2016 Ranked Summary Table.jpg

Review Summary

Normally I include a Pros/Cons table in the summary, but in this case it is not appropriate (this will be included in the individual reviews). Instead I wanted to mention how to look at these results. You will all have specific needs, you may want a large or small knife, you may absolutely want a knife needing no maintenance (apart from sharpening), you may have a strict budget, or dive in conditions where you often lose knives, so despite what looks like a clear winner in this test you might chose another option.

All the tests in this Mega Review have been carried out with the knives treated as equals, using the same conditions and testing criteria throughout. You may not be surprised to see that the two top scores are from the two most expensive knives, (you really do get what you pay for) which also happen to be from specialist knife manufacturers. Also scoring well are the Titanium blades, even up against steel blades.

 photo 10 Dive Knives underwater P1000850.jpg

I’m purposefully avoiding making absolute conclusions here as the experimental results speak for themselves. The individual reviews will be completed and published as soon as possible and the links will be included at the beginning of this article.

This information should allow you to form your own opinions about what you might look for in a dive knife.

Though I didn’t want to pick one out of these as a winner, there is the question “Do I have a favourite?” – Yes I do. Quite simply for the complete lack of care required in maintaining it, the light weight, the sheath retention and overall package, for me it is the Promate Titanium KF593 Scuba knife. Others come in very close seconds, and are also excellent choices, but if I had to pick one, and have in fact been doing that since the initial testing, it is the Titanium KF593. I also have to give a mention to the Benchmade 112S H2O as if I knew I was going to be doing a lot of cutting, then this knife would overtake the Titanium blade for quality of cut and edge retention. If you follow the philosophy that “one is none, two is one” then, like me, you might carry both of these.

It’s been fun…….
 photo 07 Dive Knives Group Police IMG_20160724_110726.jpg

 

Discussing the Review:

Please feel free to add comments to the review, but the ideal place to freely discuss these reviews is on a forum. If you started reading the shorter forum version of the review, but followed the link this full exclusive review, please return to that forum to discuss the review there.
If you read the review entirely on Tactical Reviews, please consider one of the following to join in any discussion.

EdgeMatters – Sponsored Reviews (UK based Forum for Knife Makers and Collectors)

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