Ultralight Design Evolution

If you are going to design ultralight kit then you need to start to think about things a little differently. A lot of current kit is not designed to be heavy - it's just a side-effect of all the other design decisions that were made. If you just try and do a lightweight copy of something that already exists you may not actually make much of a weight saving. If you think of a 'new' way of solving the problem then you may do better.

To illustrate the principles I've taken the evolution of the Potty Trowel that I carry. It started at 90g and ended at 28g. But the one at the end looks nothing like the one at the start.

OBTW I tend to actually carry the Mk3 rather than the Mk4 - it's a bit more comfortable to use and a bit faster to dig with and for me that's worth the extra 13g...

1. Requirements

If you are staying out in the wilderness there is a need to be able to dig cat-holes. If this was not so then you would never bother to take a trowel with you.

So, the first requirement is that you have something that can be used for digging. This is the fundamental one. If it does not dig it is useless to you.

The second requirement is that it must be a 'reasonable' weight.

The third requirement is luxury / convenience. The B&Q Trowel is the easiest one to use in soft ground but is also the heaviest.

2. Existing Products

The simplest thing to do is to hunt around on the web or in your local shops to find a trowel that is the lightest of its kind and is still usable.

In my case It was was the cheapest trowel that B&Q did.

3. Modify Existing Products

It takes a lot of time and effort to design and build something from scratch compared with buying something already made or modifying an existing item.

By taking the B&Q Trowel and chopping the handle off it I reduced the weight by about 1/3 but also reduced it's usability by more. However, it took no time at all to saw the handle off. The result was Mk 1 Trowel.

4. Design your own Lighweight Copy

The Mk1 trowel was the easy option.

The Mk 2 involved me thinking about how a trowel could be made out of aluminium with the tools, skills and materials that I have. The Mk 2 still looks very much like a Trowel and of course does still dig holes.

The problem with the Mk 2 is that it is still rather heavy and also has a point-of-failure in it. The central weld was very difficult to do (and I'm not sure that it was sufficiently strong) and it is placed under a lot of stress from all directions in tough ground.

Finally, the Mk 2 Will bend because the aluminium itself is of the untreated sort and so is quite soft. The size of the trowel means that hard ground can provide quite strong leverage onto a soft material.

There is no doubt that if the thing was made in Titanium by someone with welding skills or sheet-rolling skills then result would be absolutely fantastic. There is also no doubt that there is no way that I could do such a thing.

The Mk2 could be shrunk to the size of the Mk4 and at this size no doubt it would perhaps be much stronger and also much lighter.

If the base-plates of the Mk2 were rivetted together instead of 'welded' then it might well be very strong and versatile.

5. Review the Engineering

The Mk3 was looking at ways of removing the point-of-failure from the Mk 2 Trowel , reducing the weight and increasing the strength.

When thinking about the Mk3 I went back to the absolute basics - what is needed to make a hole in the ground.

I looked at traditional digging sticks as used by hunter-gathers and I looked at making something like that in aluminium. I also looked at whether or not several v-shaped tent pegs could be mounted together to create a good digging tools.

I looked at how efficient a digging tool needed to be.

For example, if I took a spade into the wilderness I could dig a cat-hole with a single use of the spade. If I took a 13g Tent peg with me then I could dig a cat-hole in a few minutes with legs crossed.

Somewhere between those two was a place that I could be comfortable with.

I looked at durability. Do I need my trowel to last 50 years? Would I be happy with a trowel that lasted only two years? Would I be happy with a trowel that lasted only for one trip ? (No!)

At this stage we are not thinking outside the box. Instead, the box has been thrown away so that there is no "inside the box" and no "outside the box".

6. Experiment

If you are hung up on ideas like 'success' and 'failure' you are going to find it difficult to find the limits of what will work and you will exclude lots of idea that seem 'silly' or 'risky'.

The Mk 4 is a shrunk version of the Mk 3. There is however no obvious leap you can make from the Mk1 to the Mk4. The Mk4 does not even LOOK like a trowel. It looks more like some bloated tent peg.

But hold on a second... What is the difference between a tent peg and a trowel??