First thing you need to know is that the dive knife is not a weapon, it is a tool, just like any of your kitchen knives. It is likely that you very rarely use the dive knife and is sure that you won’t deal with situations involving danger of death for a diver... but it is very important to take a diving knife with, and even two if you are cave diving.
The main and most important use of the knife is to free you or your buddy in case you get stuck in a fishnet or with vegetation. Although it may seem that this is unlikely, as many marine species fall prey in abandoned or active fishing nets, your fins, regulator or pressure gauge can also be caught by, putting your life at risk. If that ever happens you would appreciate having a knife. There are unfortunate cases such as this diver of Seville (Spain), who died in October 2012 trapped in one of these nets. A simple knife would have saved him.
Although less likely, it could also be a case of getting caught in thick underwater vegetation and then a few simple cuts would quickly free you.
The most commonly use that dives gives to dive knife is also associated with fishing nets, but to release wildlife. You can save the life of species that fall into these networks like a sea turtle with the simple aid of a knife. If one day you are presented with a situation like that and you do not have a dive knife, you will not ever forgive yourself. In the following video you can see how these divers were able to release a whale shark from great suffering. This poor shark was dragging this fishnet for years curtailing its skin.
This divers saved a whale shark from enormous suffering with a simple knife
Another common use of the dive knife is to alert your buddies of your position or the presence of some element in the sea that deserves to be seen. Few underwater sounds are as recognizable as the clatter of a knife hitting the tank.
You can carry the diving knife in the leg, in the vest, they can be made of titanium, stainless steel, be rounded or sharp, be longer or shorter, but once you start diving grab a knife and carry it around with you. We explain here the different types of diving knifes and a couple of examples of each kind.
Types of dive knives
The first thing you have to think about is what kind of diving will you do. You will not use the same knife (or sometimes the same number ) if you do technical diving than if you dive in caves or if you a simple dive in shallow water. When you decide to purchase a diving knife you’ll see, especially if it is the first time that you go to buy one, that the options are many more than you thought.
One of the first considerations you have to make is about the shape and whether you want it pointed or blunt. In my opinion a pointed dive knife could bring more problems than benefits. As mentioned, the dive knife for what is actually used is to cut and have a sharp tip can cause some inadvertent puncture in the regulator, in the wetsuit or even hurt you. The pointed knives are often used more for spearfishing. Another interesting option are the scissors knife. If the dive knife is mainly used to cut, why not take a pair of scissors?
When you arrive to the dive shop, or any online dive gear shop, you'll notice knives have both saw sharp edges or smooth... and even a serrated edge and one smooth. Choose the latter, with each edge of a style, since a single knife will serve for different situations. When you need to cut a thick or a branch out you can use the serrated edge and when you need to cut a fine place or vegetation will use the plain edge.
An interesting feature that many knives have is a short rope around the handle or tip that lets you quickly cut nets and gillnets. Almost every dive knife has it, but check twice, is very useful.
Regarding dive knives, the bigger is not always the better. The most important thing is to be comfortable and to be large enough so that your hand rests firmly in the grip. You'll be taking the knife safely in your leg (although more and more divers who prefer to put it in the jacket ) and you have to feel comfortable with it. The dive knife, as the diving mask, the less you notice underwater, the better.
Normally, dive knives are made of stainless steel or titanium. The stainless steel can corrode quickly due to its carbon content and requires more maintenance. The titanium is more expensive and almost need no maintenance and you 'll have it with you for longer (if you do not lose it, which is quite common, by the way)
In summary, the dive knife is a necessary element we hope you never have to use it and if you have to we hope is to save some animal species that have fallen into a fishing net. As for the diving knife to buy, I recommend it to be a dual serrated and smooth and made of titanium, but if you are someone who has already lost the dive mask, usually forget something of the gear in every dive center you visit and do not know where you have your logbook , buy a very cheap dive knife, you are going to lose it :-)
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