Choosing a dive knife

Regardless of which type of scuba diving you’re interested in from wreck diving and cave exploration to simply taking nice tropical fish pictures you will find a dive knife a very good and helpful accessory. A lot of dangerous situation can arrive under water such as getting entangled in ghost nets and a dive knife will help you escpae many such dangers. When taking tropical fish pictures you may for instance become so absorbed by your task that you don’t notice that large ghost net stuck on the outside of the ship wreck where the most spectacular lionfishes are playing peek-a-boo with your camera. In such a situation a good dive knife will help you free yourself from the net before things get critical.

You should consider the following things before buying a dive knife

- Choose the right scuba knife; one that suits you and your particular needs.

- Make sure that you know how to use the kind of dive knife you choose to get. A sharp knife in the hands of an insufficiently prepared diver can cause more damage than what it prevents; especially in a panicky situation.

In this blog post we will take a closer look at the first point choosing a dive knife.

What size should the knife be

There are three main sizes of dive knives, big knives, mini knives and standard sized knives. A standard size dive knife, also known as medium size dive knife, has a 4-5 inch or 10-15 cm blade and is small enough to comfortably keep mounted on your leg, arm or BC. Make sure the handle is large enough for you to grip without much ado. Mini Knives are 2-3 inches (5-7.5 cm) and can be mounted on the air tube. Unfortunately, many of them come with handles that are difficult to grab underwater, especially when wearing diving gloves. It is therefore extra important to try the handle on a mini knife before buying it. Big dive knives have blades that are 5 in / 15 cm or longer and can be a tad cumbersome to handle underwater, especially for precision work. When scuba diving, big doesn’t automatically equals better so only get a big scuba knife if you know that you will be doing things underwater that actually require a big knife.

What material should the knife be made from

Most dive knifes are made from titanium or stainless steel. Titanium knives tend to be the most expensive choice, but are on the other hand extremely resilient to rust and other types of corrosion and a good titanium knife will stay sharp for numerous dives. Stainless steel knives are cheaper can be made to last for a long time with proper care like making sure to always rinse them in fresh water after every dive. It is a good idea to coat it with oil or silica.

Should the knife have a serrated edge?

A serrated edge is ideal for cutting natural fibres such as hemp ropes and kelp, while a straight edge will be more apt at cutting artificial materials like nylon ropes and monofilament fishing lines. If you decide to go for a serrated knife, ideally pick one where the serrations run almost the entire length of the blade to make it possible to get a nice sawing motion going when you need to cut something. I recommend that you get a knife witha serrated edge on once said and a straight edge on the other, that way you get the best from both worlds.

Should I choose a knife with a sharp tip?

Sharp tips are popular among spear fishers, but if you plan on using your knife for something else then a blunt tip is usually to be preferred. A sharp tip will easily break if you try to use your knife to hack, chisel, pry, dig or similar. Having a knife with a sharp tip will also increase the risk of accidently puncturing a BC your own or your dive buddy’s.

Do I need a line cutting notch?

Yes, a cutting notch will make it much easier to cut small lines and other potential dangers.