In reality the decision would depend mainly on the terrain but in perhaps 80% of wilderness backpacking trips most people would take both. In the interests of keeping the rucksack weight to a minimum, taking only one would be more sensible.
Considering the wilderness backpacker’s likely needs guides us more to a small axe or a hatchet. Gransfors axes are legendary and one in particular is ideal for our purpose. All Gransfors axes are of excellent quality, hold a good edge and have a traditional design consisting of a forged head and a hickory shaft.
This design is favored because you can craft a new shaft in the field should this be necessary in an emergency, using only the axe head; this is not an option with an axe that has a thermoplastic shaft moulded around the axe head.
Let’s now compare the knife and the axe in some basic tasks. For this comparison the knife used is an Eka Nordic W12 (Blade length: 120mm/4.7″ Total length: 230mm/9.6″ Blade thickness: 4mm/.16″ Total weight: 268 gram/9.5 oz.) and the axe is a Gransfors Wildlife Hatchet (Length with handle: 13.50 inch). Both the knife and the axe are shaving sharp.
There really is not much between them when making feathersticks, the knife being marginally more controllable due only to the curved face of the axe. However, if you are experienced this becomes almost unnoticeable.
Here the axe wins hands down, no question; you will collect the firewood you need in a fraction of the time with an axe. There is also a technical reason that an axe is better; wood burns on the surface only so if you split a 100 mm diameter log into four, collectively they have much more surface area generating heat. You can still split timber with your knife but it takes much, much longer.
This is another area where there is little or no difference. The knife and the axe are so sharp that accurate carving can be done with both quite easily.
Again, because the knife and the axe are so sharp, all the tasks involved in preparing animals for cooking are easily achieved with either.
Building a Shelter
Due to unforeseen circumstances you may need to build a shelter or just decide to stay in one place for a few days and not use your tent; an axe in these situations becomes invaluable and the knife, understandably takes a back seat.
Refinishing the Cutting Edge in the Field
The axe comes out on top here as the shape of the cutting edge is vastly different to the knife. The cutting edge on an axe is a bevel and can be brought back to a shaving sharp edge more easily.
A knife may be carried on the belt, on the rucksack or in the rucksack; the axe is exactly the same but slightly more cumbersome on the belt than the knife.
A quick word on safety. Both the knife and the axe will be extremely sharp, they need to be to fulfil our needs; a mistake with the knife can inflict a serious wound but a mistake with an axe is on a different level altogether. Always have your first-aid kit close at hand and not buried in your pack.
The Local Laws
The area you are in may be a National Park or equivalent and as such have certain rules that need to be adhered to under normal circumstances. However, if you find yourself in a true survival situation through whatever reason, it is extremely unlikely that you will be penalised for breaking these rules.
My own experience is that an axe is a better tool to take if you have to choose. Of course, this saving on its own will only make a small difference, the weight of the knife. However, once a rucksack reaches 25 kg it starts to affect safety on severe terrain, so if you can, keep it under that; keeping the weight down becomes more difficult with wilderness backpacking because you need to be completely self-sufficient.
The additional fact that many people who engage in wilderness backpacking venture out alone makes the normal procedure of splitting some gear between perhaps two or three people to keep individual rucksack weights down no longer an option. You will find that as your skills improve you’ll take less equipment, this being replaced with knowledge and confidence in your own ability.
Try some tasks for yourself and see what you think. You’ll be surprised at how versatile an axe can be.