Spearfishing Knives

Introduction

Another piece of gear that is useful is a knife. This can be used for the following reasons:

• To "brain" (kill) a newly caught fish
• To cut line, a net or kelp if you get tangled
• To gut/ clean a fish
• To dig your spear out id certain cases if it gets stuck
• I guess you could also add to defend yourself
• Some knifes allow you to straighten your spear or leverage it
• It looks cool :-)

There are different types of materials, shapes, sizes, etc; so it is not an easy choice! Here is an image describing the main parts of a knife:

Source: http://www.leisurepro.com

Blade Materials

This is an important thing to think about, it will determine the weight, robustness and corrosion resistance of your knife. The following are the main types:

• Steel: Cheap, heavy, robust, maintains a sharp blade, easy to sharpen, but rusts, must maintain it very well by rinsing it with fresh water (as you should with all your gear), dry it, grease it and store it in a dry place.
• Stainless Steel: Heavy, robust, maintains a sharp blade (more than Titanium), easy to sharpen, corrosion resistant. There are two types generally used for dive knives:

        - 300-Series: More corrosion resistant but it loses its edge quicker
        - 400-Series: Stays sharper longer but more susceptible to rust

• Titanium: Expensive, Light, fairly robust, maintains a sharp blade (less than SS), a pain to sharpen, the best corrosion resistance

Number of blades

A knife can have one side that cuts (I will call this one blade) or two (I will call this two blades). Most spearfishing knives have two blades. The advantage of one bladed knives is if you have to be able to press on it to cut though thick things, this is not really needed for spearfishing though. A two bladed knife can have a mixture of blade types in one knife, see Blade Type below for more info.

Blade Type

There are two types of blades:

• Straight: the conventional type, it is used to cut fine things such flesh, fishing line and other fine lines. If you only have one blade on your knife it will be of this type 9 times out of 10.
• Serrated: this is like a saw and useful to cut through tougher things like bone, rope, kelp, etc. They tend to stay sharp longer but are a pain to sharpen (sometimes impossible).

Size

Size matters ;-), but not necessarily the way you think!

• A long blade is useful for self defense, cutting fillets, as leverage, etc.
• A short blade is good for stealth and it makes it easier to brain a fish.
• A thin knife (including handle) is good for stealth and hydrodynamics but is less comfortable to hold.
• A thick knife (including handle) is comfortable but can get caught up in kelp, line, nets, etc.

Curvature

You can have either curved blades of straight blades, it is mostly a preference and often depends on the tip type and usage.

Blade Point/Tip shape

Here are the main types of knife tips you will encounter in diving/spearfishing knives:

Knife tip types

1. Clip point: This is the shape of most hunting knifes, the tip has a clip taken out of it on one side. It is usually a one bladed knife and seldom used for spearfishing.
2. Drop or Spear point: these are actually two different points but I grouped them together since they have the same shape. The difference is the drop point only cuts on one side. They are shaped like a Swiss army knife blade. Some people like them but they are hard to use to brain a fish with a hard skull due to the rounded curvature of the blade. I have one (on my ankle) with a long blade (13cm) that I use to gut fish, cut my way though things, dig (since the point is still strong due to its shape). This is a common shape for spearfishing knives.
3. Needle-point (aka Stiletto): This shaped live a thin V, it is very efficient for braining fish and cleaning them. It is however more fragile at the tip than the other knives. I have a small one (8cm) on my biceps that I use almost exclusively for braining and gutting fish. This is a common shape for spearfishing knives.
4. Blunted: the tip is flat and may or may not cut, this is very useful if yo have to dig things out & pry things open since sharp points can break. It is however harder to use if you need to gut a fish or stab something. They are rarely used in spearfishing.
5. Tanto: This is like the tip of certain Japanese knives, the tip has very square lines. You can see it as a mix between the blunt tip and the spear point tip (the good sides of each). It is seldom used for spearfishing however.

Position on the body to wear knives

Where to put a knife? It is mostly a personal preference, the main spots are:

• Calf: Most common, easy to grab. Possible to grab with both hands if necessary. It can get caught though when you are swimming though kelp, nets, line, etc. Can be worn on the inner calf to offset this last point but can then rub against the other calf.
• Thigh: Possible to grab with both hands if necessary. May be uncomfortable since your thigh muscles work out a lot.
• Forearm: Can only be grabbed with one hand, on the opposite side. If you have a dive watch it could make it harder to grab.
• Biceps: Can only be grabbed with one hand, on the opposite side.
• Belt: Possible to grab with both hands if necessary.The issue with putting it on the belt is that if you have to quickly release it (weights) you lose your knife. The through of this could make you think twice, thus endangering your life. I think it is therefore better not to where it on your belt.

Number of knives to carry

So, one knife, two, more? I think one knife is the most common, I prefer to have two. The reason for this is:

• Safety: if I am stuck I may not be able to grab the knife, if I have two it minimizes this risk.
• Different needs: I use the knifes for different reasons, my small one is for braining, and gutting, the big one for leveraging, cutting lines, protection, etc. If I had to do it all over again, I would maybe take a blunted tip for the big knife.
• Backup: if I lose one (and I probably will one day) I still have another one on me.

Misc

• Coatings: Some knives have coatings, like Teflon. This protects against rust; even SS can rust in salt water (if your SS is 400-series to keep a good edge it will rust a little).
• Line Cutting Notches: some knives have a notch or hook in the blade that is used to cut line, this is very useful.
• Scissors/cutters: some blades are actually also cutters/scissors. Imagine if you sharpened a blade on the outside if scissors. This can be useful to cut line and nets, to cut through fish bone and flesh.
• Folding knives: you can get a folding knife, I personally am against this since it is not ready when you need it, they are hard to grab and can be dropped, the are hard or impossible to open with gloves. I really see no advantage.
• Knives allowing you to straighten your spear or leverage it: nice to have

I have two knives, I wear my big knife (XS Scuba Titanium: spear tip with straight and serrated blades, quite big, line cutting notch) on my calf and I wear my small knife (Omer Mini Laser: Stainless Steel, needle tip with straight and serrated blades, quite flat, Teflon coating) on my biceps.

Some knives I like

Spearfishing knives

• Riffe Silencer: hardened (heat-treated) 420 stainless steel, Teflon coating, plain edge and serrated edge, needle tip, medium (11.5cm blade). I read however that the sheath is bad ans you can easily lose the knife...
• Riffe Terminator: hardened (heat-treated) 420 stainless steel, Teflon coating, plain edge and serrated edge, needle tip, medium (11.5cm blade)
• Riffe Terminator II: hardened (heat-treated) 420 stainless steel, Teflon coating, dual serrated edges, needle tip, medium (11.5cm blade)
• Omer Laser: 420 stainless steel, Teflon coating, plain edge and serrated edge, needle tip, different sizes available (mini: 8cm, normal: 9cm, Maxi: 13cm)
• Salvimar ST-Blade: plain edge and serrated edge, needle tip, small (7.5cm blade), flat, strap to secure on hand, Stainless-Steel, shaft extractor/straightener
• Salvimar ST-Atlantis: plain edge and serrated edge, needle tip, medium (9.5cm blade), flat, strap to secure on hand, Stainless-Steel, shaft extractor/straightener
• Picasso Tiger: extremely flat (handle is bare), Stainless steel, shaft extractor, line cutting notch, shaft diameter measuring holes, medium (10cm blade), needle tip
• Speardiver Skene Spearfishing Knife: extremely flat (handle is bare), long (11cm blade), Teflon coated Stainless Steel tempered to 55-56HRC hardness, plain edge and serrated edge, line cutting notch, needle tip
• Extrema Ratio Ultramarine: very flat, super expensive, Cobalt Steel N690, line cutting notch, plain edge and serrated edge, spear extractor/straightener, spear tip.

General dive knives

• Scubapro White Tip: 304 stainless steel, blunt tip, medium (6cm blade), flat, plain edge and serrated edge
• XS Scuba Titanium: Big (13cm blade), different tips available (spear, blunted, Tanto), plain edge and serrated edge, line cutting notch, good knife

I hope this will be useful for someone! Please, if you have any comments or if I wrote something wrong, if I forgot something, if you feel some extra information would be useful or that you don't agree with something I wrote, tell me with a comment.