Pitdog,
I would start by defining what I believe a survival knife is. Effectively, any knife which allows you some modicum of comfort or efficiency is a "survival knife" but I'll assume for now the definition is a jack of all trades, general purpose knife. Where you live may have much to do with what such a knife implies.
On the one hand you may be planning for being alone in the near-by wilderness reasonably close to home and have suitable equipment along with the knife suitable for some reasonable period of time. On the other hand you may be preparing for some safari, hunting trip or vacation in totally different terrain and perhaps are planning for the unlikely event that that trip of a lifetime goes horrible awry.
Whether the plan is to stay in the wilderness (on purpose) for some protracted period of time, or finding oneself in the wilderness quite accidentally and as temporarily as possible will demand different attributes. I'd analyze the following before deciding which knife (assuming hypothetical situation of being forced to choose only ONE such implement):
Terrain and vegetation - the best choice for thick jungle is not ideal for the desert, though any knife is better than none. From vegetation and terrain, I would determine other attributes I'd need of my equipment.
* Weight, balance and length - generally a lesser concern if you have several knives and select the most appropriate one for the task, this can be a major issue if you can only choose one. Fatigue from using a knife that is too heavy and/or too long for the task, or too short and light have the same effect on your stamina and ultimately morale.
* blade geometry and edge - a highly curved blade tends to be very specialized (the Khukuri being an exception) and therefore probably not suitable for general purpose use. A blade with a reasonably sharp point for boring holes and piercing, a good belly for slicing and an easy way to grab the blade for more delicate work (especially important for long blades) are very useful. A plain edge is more general purpose than a serrated one and considerably easier to sharpen in the field with limited access to abrasives.
* Edge retention/ease of re-sharpening - Very hard blades with great edge retention tend to make awful last-ditch general purpose field knives. If it is difficult to resharpen, it is probably unsuitable for general purpose use. It is preferable to have a softer, tougher blade and edge that is more easily sharpened.
* Materials and construction - In almost every case, I'd choose a simple medium to high carbon steel, or a relatively simple alloy steel that is very well tempered and annealed. The one exception is if I planned on being on a tropical island, but having lived on the coast I can say most of the corrosion is on the surface, is a black oxide instead of a red rust under most circumstances and easily removed. Surface coatings can help but invariably wear off with hard use. Cleaning the blade and avoiding sheathing the knife in a wet sheath (or one which tends to sop up moisture, i.e most leather sheaths) does much to make this practical. A full tang blade construction, epoxied and riveted, makes for a strong union between grip and the blade's tang. Guards look cool but tend to get in the way, finger grooves are less useful if you hold the knife in a different grip then intended as can happen with a general purpose knife used in novel ways. A haft that is well textured and devoid of the slick, smooth, waxed look that makes for great glamour shots in knife magazines is unsuitable for the sort of life or death utility this role requires.
How long you plan to be out there will also have some affect on what you'd be packing for. I wouldn't take only a single knife, or a single change of clothes for that matter if I had any choice at all.
For example, In dense woody jungles with tall, thick grasses, I'd opt for a large, long bladed but fairly light knife. The various Goloks and Barongs, some of which supply a fairly serviceable point, are among the best. The main task here, other than finding a road or a river to follow to get out of there, is shelter building for heavy rains, collecting wood and making tinder out of whatever dry material you can find.
If I were in dry, open terrain with harder woods and nothing to hack out of my way, I might opt for a medium length knife with a blade in the 10" range or I might even opt for an axe instead of a large knife. Small tasks can be handled fairly well with a sharp hatchet or small axe, the biggest task being to shelter from the sun, mashing cactus and edible succulents for food and water content and stripping off and breaking up enough plant material to insulate from the ground and provide a wood supply for keeping warm at night when the desert temperatures plummet. Most little critters you trap or hunt only need a few slits to peel their skins off, hatchet or knife work equally well here.
In mountainous terrain, you'd want to get down to the treeline for any useful resource to sustain yourself. In some cases, there are fewer variations in species within a given location until you go further down in elevation. If you have to make due with downed mature trees to overnight, you'll really want an axe or a very large, heavy knife to limb the large branches and leave the trunk alone after stripping off any useful bark. Insulating from the cold and wind, avoiding losing heat to the ground by creating a palette or raised platform, a small, body sized shelter, a truck sized stack of wood for keeping a fire going during the night.
There are many, many variations on the theme, but even "general purpose" should be adapted to where you are or are expecting to be if you somehow manage to have only that one tool left among all your worldly possessions.
Good luck,
-E
:thumbup:
