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Dive knives- for digging, prying, prodding, befriending fish, sawing through very thick ropes, possibly for use as a screwdriver, and as a last resort during entanglement- Knives are TOOLS FIRST and SAFETY EQUIPMENT SECOND. If in an emergency, a knife has a higher probability of cutting your gear or yourself than shears or other cutting tools. Use your knife for digging, prying, prodding, and sawing.
- DO NOT get sentimental about a knife. DO NOT get attached to your knife. DO NOT try to retrieve your knife if you lose it. Knives are disposable pieces of gear.
- Knives are the most likely piece of gear to be lost on a dive.
- There is little a diver can do about animal attacks. A sharp knife will not help very much in the event of an attack.
Knife edges / Sharpening- A good dive knife should have a serrated edge on it somewhere. Underwater, it is hard to get leverage against an object you are cutting. Thus, most cutting during dives is actually sawing.
- Straight-edges on dive knives are supposedly better than serrated edges when cutting natural fibers and hard plastics or plastic fibers.
- Sharp tips are more likely to puncture equipment, harm other divers, harm their users, harm rescue victims. Blunt tips are better for digging and prying.
- There's a lot of thought put into
traditional knife shapes. Any taper or dropping-point on a blade is meant to focus force onto a smaller area of the blade to maximize cutting force in that area.
- To sharpen steel or titanium, watch youtube videos. You may find that you need a diamond stone or whetstone and ceramic sharpening sticks (
guide here). Strops are expensive and only really needed for sharpening blades you plan on shaving with (as far as I know).
- Large knives (with large handles and protruding sheathes) are more likely to cause entanglement (and injury). A small 3'' blade will be just as useful as a large knife.
- Flat nylon sheaths are less likely to get caught on seaweed.
- Click-in sheaths tend to lose their knives (Possibly with the exception of the Wenoka squeeze lock click-in sheaths -- suppposedly they don't have any problems).
- A knife should not be worn on the outside (lateral sides) of the body. In the event of an emergency surfacing, dropping tanks could snag on equipment worn on the outside of the body.
- The standard position for a knife to be worn is on the front of the diver's waist-belt. It is important to standardize placement of equipment in the event that a dive buddy needs to find your equipment quickly.
- Low-profile knives are easier to hide from people who would tell you you can't dive with one.
- Folding knives are cumbersome to use with gloves on. The best dive knife might be a non-folder.
Metal types- Titanium (Ti) knives are easier to break than Stainless Steel (SS), but do not corrode in seawater. Because they do not corrode, they always stay sharp.
- Ti knives are more expensive than SS.
- Higher carbon steels (common 420 steel, for example)
corrode faster/more than lower carbon steels (304/316 steel). [
source]
- H-1 steel is made from some nitrogen-iron composite and is supposedly 100% rust/corrosion resistant (but expensive).
