I have almost always worn a dive knife, regular sized, and without reservation or embarassment. A dive knife is a necessity, as it will get a diver out of lines, nets, etc., and can also be used for prying.
Here's some of the uses I've put my knife through in my diving career:
--Cut two Korean pilots out of their parachute harnesses and tangled lines after they were ejected on impact through the canopy of their F-86 when it crashed into the Yellow Sea. The pilots had not survived, but at least their bodies were recovered by our helicopter rescue crew. Without a knife, that would not have been possible.
--Regularly cut fishing line to collect fishing lures and weights out of the Oregon rivers I dive. I also use the knife to pry the weights out of crevices they've become lodged into in the rock bottom. Recovering lead weights does two things: 1. It rids the water of lead, and that water is used for drinking water by many municipalities. It also helps get toxic lead out of the river for the aquatic life. 2. They can be used for diving weights with the appropriate molds (however, I gave mine to a fire department over 10 years ago, and haven't seen it since). That means free weights. Lures cost $1 to $2.50 each, and it's now pretty easy to get ten to twenty dollars worth on a dive in the right places.
--Cut monofilament line that has become entangled in my equipment.
--I used my dive knife to cut about a 3 inch diameter rope and fishing net, the top rope of a fishing net, off the anchor of a missionary ship on Thetis Island, BC when I was a teen. A knife needs serrations to do this kind of job, and it took us about half an hour of cutting to get it off.
I currently dive a Wenoka Sea Style dive knife with a 5 inch blade (which may not be made anymore). The blade has a line hook in it, and two serrated areas (one on the top about two inches long, and one near the line hook about 1.5 inches long.
This knife has a button locking mechanism in the handle (which is red; I like it to be bright), and can be handled one-handed. I attach it to my right calf, usually on the outside, but will rotate it to the inside if there is a lot of kelp or other sea weeds around. Its handle can also be disassembled for cleaning by unscrewing the top cap, unscrewing the locking mechanism with their special key, and sliding the plastic handle out. This makes for good cleaning, and corrosion prevention. Even "stainless" steel will corrode if exposed to salt water and not properly cleaned, dried and oiled.
I highly recommend keeping your knife very sharp, either by learning to use a stone/steel combination or by taking it to a cutlery periodically to be sharpened. To be effective, it should be sharp.
Diving knives are not macho, self-defense weapons, such as is seen in the movies. They are tools that will allow a tangled diver to get out of trouble, and should be treated with that respect, kept sharp and corrosion-free, and worn on every dive. You never know when there may be a need, and if you do need a knife, it's usually too late to go back on shore to get it.
SeaRat
