How To: Guide to Knives
Knives are like any piece of equipment - mix of various compromises that often negate each other. Before purchasing a knife, there are many things to consider about knife, its purpose and the actual way it is going to be used.
Purpose of the Knife
Before buying a knife, first we must think about its actual purpose. When (sea) fishing, there are plenty of opportunities for good knife to be used: cleaning and/or filleting the fish, preparing baits, preparing food, diving, chopping wood, self-defense, digging etc.
Also, it is not the same where will the knife be used - if you are going for a fish trip with a boat or car, then weight of the equipment is not a problem; if you are going on foot and you are carrying all of your equipment, you will try to lessen the carried weight as much as possible.
Who will be using the knife, most of time, is also very important issue - I got my first knife when I was 7 or 8 and it was a real hunting knife.
Note: Giving a kid a knife is not popular these days for various reasons, but if kid doesn't start to learn the responsibility very early in life, when will that kid have time to learn? Just my 2c regarding this issue, now back to knives...
Multipurpose knives or even Swiss Army Knives can come very handy in various situations. Most of the Swiss Army Knives are relatively small and lightweight with plenty utilities on-board, so it is recommended to always have one with you, when going for a fishing trip - they lack robustness of dedicated tools, but they do come handy :) And they are great gifts!
Material of the Knife
Several material are used for making knives - blades, handles, sheaths etc.
Steel is most common material for making blades. Exact characteristics depend on the type of used steel - when writing reviews about knives, we are trying to find out what steel was used and to write down several characteristics of that steel.
As with everything in life, where you get something, you lose on something else - similar is with the steel.
Stainless steels have various alloying elements that increase resistance to rust - most commonly Chromium and Nickel. For example, some very resistant stainless steels are easily sharpened and hold the edge very well, but they are brittle and can break easily. Stainless steels that are rust resistant, that hold edge very well and at the same time are flexible enough do exist, but they are expensive due to special alloying elements like Vanadium, Cobalt etc. Stainless steels are used for diving and filleting knives and equipment that is generally used in chemically aggressive environment.
For example, Kershaw 1259 Fillet Knife is made out of 420J2 steel, which is very cheap stainless steel, not suitable for swords and sabres - it doesn't hold the edge very well in such blades. Its maximum edge hardness is around 52RC, with hardening it can go up to 54RC. But, it is easily sharpened, it is very, but really very corrosion resistant. After usage, clean the knife, wash it with fresh water, dry it and put back into the sheath. This steel is very durable and if you don't mistreat the knife, it will not break. And it is a cheap steel.
Carbon steels are used for making very tough knives that can withstand plenty of punishment while still holding their edge and without breaking. On the other hand, they are not so corrosion resistant like stainless steels; often such knives are chemically treated to increase their resistance to weather and other elements that can cause them to rust. Carbon steels are very often used for making survival, combat and similar knives that are used for various purposes.
For example, KA-BAR Fighting/Utility Serrated Edge Knife is made out of 1095 Steel: this is a high-carbon steel for knives and similar blades. It is harder but more brittle than lower carbon steels such as 1055, 1060, 1070 and 1080. It has a carbon content of 0.90-1.03%, which is responsible for its toughness and ease of sharpening. Blade is very solid, capable of absorbing plenty of punishment.
Spring steels are types of steels popular for swords and large knives. They are popular for high toughness and good wear resistance. Edge retention and corrosion resistance could be better, but whatever you do to them, they are almost impossible to be broken.
Tool steels are special alloyed steels used for production of various cutting tools - they can be very expensive, but also can provide blades with exceptional qualities. Some of more known and popular steels are A2, D2, O1, M2, M4 etc, but many others are used.
Ceramic blades are used for knives that are used for slicing soft food. They are extremely sharp and hold their edge very well, but they are also extremely brittle - if you drop them on the floor, they will probably break. Nice for kitchen knives, but for good and reliable knife that can be used in multiple ways, ceramics is not a good blade material.
Titanium blades are very popular in high(er) end diving knives due to high rust-resistance. Such knives are also non-magnetic, if they don't have other parts made from steel. Titanium is lighter than steel and for the same mass is actually stronger than steel. For the same volume and size, titanium is generally weaker than steel. Titanium is also softer than steel and doesn't hold the edge so well. This is often remedied by using carbides for blade edge and/or special titanium alloys like Ti 6-4 (known also as Ti6Al4V or Ti-6Al-4V), that is even up to (or even more) 3 times stronger than stainless steels - just don't compare price of such knives with stainless steel knives :)
Glass blades are rare - they are like ceramic blades - extremely sharp, but very brittle. For kitchen use only - for slicing and cutting of soft foods.
Various plastics and rubber are used for knife's parts like handle or sheath. Knife handle must provide good grip even in the hardest conditions like being covered with sweat, rain, blood, mud and other liquids and materials.
For better and easier cleaning some knives can be disassembled, but there is always a danger of the knife handle and other parts becoming loose.
Weight of the Knife
Weight of the knife varies from just few decagrams/ounces to kilo or even more for knives/machetes with large steel blades. Size, shape and material determine the weight - robust knives simply must have thick blades to be tough and reliable in the field.
On the other hand, bait and filleting knives must have sharp, thin and flexible blades - these knives are often connected with rope to floats to prevent them from sinking to the bottom if accidentally dropped off the boat into the water; reason more to be light.
Price of the Knife
Prices vary depending on the purpose, material, size etc. Some entry level diving, bait and filleting knives cost less than 10 dollars/euros and even so cheap, they will do the job.
For really specialized survival, combat and similar knives, that are made out of special steels, don't be surprised to see price tag in hundreds (even more) dollars/euros. But, such knives, if used properly, are passed on to younger generations - literally.