A review of three modern diving knives

Function Over Beauty

I like a dive knife that looks great, we all do! However,  a sexy looking knife is not much use to you if it doesn’t cut through that mono-filament line that’s wrapped around your leg! I tried three modern knives out on an assortment of materials that commonly cause diver’s trouble, from fishing monofilament to three-strand anchor line to high-tech cable-strength braids. I also subjected them to a “corrosion test,” an extended period of aquatic abuse in a saline solution to see how well they resisted rust and corrosion. Each knife was dunked in saltwater three times a day for a week. Between soaks I set the knives out to dry while still in their sheaths. At the end of the cycle, knives and sheaths were inspected. In general, the titanium and higher  calibre stainless blades were the most resistant to corrosion, while the softer 304-grade stainless knives showed less signs of rust than the harder 420-grade stainless knives. No rust spots were so imbedded that they couldn’t be buffed out with a cloth. The important thing to note here is that a decent maintenance routine will keep a modern dive knife looking new for as long as you can bear to not buy a newer, sexier knife!

Riffe Silencer

Full knife length: 9 in.

Blade length: 4.5 in.

Blade: Plain edge and serrated edge combination.

Metal: 420 stainless steel.

There Is Something About A Stiletto Blade That Just Means Business, And This Blade Means All Sorts of Business! Mostly Cutting Business Though...

The Silencer is made of hardened (heat-treated) 420 stainless steel and has cutting edges sharp enough to cut virtually anything. The 4.5-inch stiletto blade, which is Teflon-coated to prevent rusting, offers a plain edge on one side and a wavy serrated edge on the other, giving you a choice of cutting surfaces. The over-moulded handle has an ample blade guard for a safe and secure grip. It also offers a tool built into the end-cap to remove spear shafts that get wedged in rocks. The sheath comes with a pair of rubber leg straps and offers a locking push-button release. An elastic lanyard attaches to the end-cap for extra security.

The Silencer’s blade, with three inches of serrated edge and four inches of plain edge, proved to be the best all-around cutter in this review. It was the only knife able to slice through every type of test line–even the Amsteel–with a single pull, and it did it with both edges. For spear fishermen who can get wrapped in their own line during a hunt, this is the Silencer’s strongest selling point. But the sharp stiletto point is a winner too, designed to quickly dispatch a struggling fish. While the blade is Teflon-coated to prevent rusting, the cutting edges aren’t, so by the end of our corrosion test, the Silencer was showing a couple spots of rust; however, they all rubbed out with a towel. The Silencer’s sheath is one of the best we’ve seen. A sliding safety mechanism prevents an accidental push of the push-button release. The safety and release button are both easy to operate one-handed, and the elastic lanyard can be stretched over the sheath for added security. Standard rubber leg straps have quick-release buckles and can be replaced with optional forearm stretch-straps for a closer reach.

Scubapro White Tip

Full knife length: 6 in.

Blade length: 2.5 in.

Blade: Plain edge and serrated edge.

Metal: 304 stainless steel.

Back Ups Are Important, So It Needs To Be Almost As Effective As Your Primary, The Guys At Scubapro Agree With Me!

A backup cutter should be compact, and the White Tip is certainly that. Only six inches long overall, it comes with a 2.5-inch blade offering an inch of serrated edge, an inch of plain edge, and an angled tanto tip that’s nicely blunted right at the end. The blade and handle are made from a single length of 304-grade hard-tempered stainless-steel–the handle portion is over-moulded to provide an easy grip. The sheath offers a push-button release that keeps the knife secure until needed. The White Tip comes in a kit complete with hardware to mount on a console hose or BC pocket (this requires punching holes in the material). The sheath also has slots for threading a pair of rubber straps for mounting on an arm or leg. For added security, there’s a hole in the handle for a lanyard.

The White Tip offers more mounting options than any other knife in this review, making life easy when deciding where to strap it. Removing the knife from its sheath is also easy–the push-button release can be activated with one hand. The partially blunted tanto tip takes some of the apprehension out of returning the knife to its sheath, and a solid-sounding click lets you know the knife is locked in place. Because of its 304 stainless blade, which doesn’t hold an edge as well as harder metals, and its short blade length that offers less cut per pull, the White Tip was not the most efficient cutter of the group. However, it was able to eventually cut through our entire inventory of test lines, taking only a couple pulls to get through the lighter lines, 10 to 18 pulls on the heavier lines, and 25 pulls on the Amsteel. It did a good job of resisting rust; after a week of repeated saltwater dunks it showed no signs of tarnishing.

It always makes sense to carry a backup cutting tool, especially one that’s compact and doesn’t clutter up a dive rig. We like the White Tip’s ability to bolt to a hose, a strap or a BC. But if none of these options suits you, the White Tip is so small it will probably fit into your BC pocket.

Spyderco Aqua Salt

Full knife length: 9.25 in.

Blade length: 4.5 in.

Blade: All plain edge or all serrated edge.

Metal: H-1 stainless steel.

A Mean Looking Knife, A Really Hard Worker And A Solid Bit Of Kit.

This knife is not to be trifled with. Its blade has a lethal point and comes with either a scalpel-sharp plain edge or a seriously serrated SpyderEdge (a pattern of one large and two small serrations) backed by a full-curve “belly” that produces very effective slicing-type cuts. The blade is made of rust-free H-1 stainless, a special composite exclusive to Spyderco that uses nitrogen in place of carbon in its steel matrix. This maximises corrosion resistance while still enabling the blade to hold a sharp edge. The handle is made of textured, fibreglass-reinforced nylon. The heavy-duty Kydex sheath is riveted for strength. It secures the knife with a friction lock and features a G-Clip belt fastener that can be configured in five positions to suit your diving style. The Aqua Salt is available with either a yellow or black handle with a hole for a lanyard.

Both plain edge and SpyderEdge versions of the Aqua Salt were able to cut through our inventory of line, though the serrated version had an easier time doing it. The full-sized handle let us grip and rip; while there’s not much of a blade guard, the textured handle and finger grooves keep hands from slipping forward. We cut all test line with a single pull except for the Amsteel, which took five pulls. The H-1 blade excelled in the rust test, showing no signs of corrosion on the blade and only a slight bit of tarnish on the engraved “H1? logo, which rubbed right off. The G-Clip belt fastener fits securely on a standard two-inch harness strap, and the sheath’s grommet holes offer cable-tie attachment points for added security. One-handed removal is accomplished by pressing your thumb against the top of the sheath. The large mouth makes an easy target when returning the blade home, which clicks when the friction lock activates.

If you’ve always had a hankering to take your sharpest chef’s knife diving with you, leave it in the drawer and take this one instead. Of the two styles, we prefer the serrated version for its better cutting efficiency. But neither style disappoints. A bit of advice: Mount the sheath where you can see it; a near-miss when returning the blade home can get bloody.

Final Thoughts

Knives have come a long way since the huge swords of yesteryear, they were a little impractical but were most likely a psychological crutch to distract them from the fact that their gear was far from fool-proof and the site they were diving on was unexplored. Today’s divers value efficiency and lightness and the three knives I reviewed above provide exactly that. The new, corrosion resistant and hard blades, combined with easily gripped handles and secure, convenient sheaths have revolutionised dive safety knives and have made choosing your next blade even more enjoyable!