How to make a DIY dry bag
With our bikepacking trip to Cuba only days away, we still hadn’t bought dry bags to put in the Gorilla Cages that we planned to attach to the front forks of Dan’s Genesis Longitude. We were hoping to get Alpkit 5L dry bags but the company had none in stock.
So after chickening out of a Sunday ride, we set about preparing our kit and packing for a cycle tour in a warm country and with a new bike setup. Dan tried packing the cooking gear into a tatty 8L bag that we already had and said that it would do if we were stuck.
‘Ideally, I’d like a bag that’s long and just wide enough to take the cooking pot,’ he said. ‘Otherwise the material bunches up and it looks ugly.’
That’s when I had the idea of making a DIY dry bag to meet our needs.
‘I have some leftover Cordura from when I made a custom frame bag and I’ve got some clips and straps from the 13l Alpkit bags that I could use as webbing.’
All I needed from Dan was some help to clear the table and to dig the old sewing machine out from under the stairs.
And according to the advice from a Singer sewing machine manual from 1949, I also needed to do the following:
Prepare yourself mentally for sewing. Think about what you are going to do. Never approach sewing with a sigh or lackadaisically. Good results are difficult when indifference predominates.
Never try to sew with a sink full of dirty dishes or beds unmade. When there are urgent housekeeping chores, do these first so your mind is free to enjoy your sewing.
When you sew, make yourself as attractive as possible. Put on a clean dress. Keep a little bag full of French chalk near your sewing machine to dust your fingers at intervals.
Have your hair in order, powder and lipstick put on. If you are constantly fearful that a visitor will drop in or your husband will come home, and you will not look neatly put together, you will not enjoy your sewing.
I took heed of the first paragraph and ignored the rest.
Now, let’s get on with the process of making a DIY dry bag.
What you’ll need
Male and female plastic clips (side release buckle)
A used washing up liquid bottle (for the plastic stiffening in the opening)
How much fabric do I need for a DIY dry bag?
First you’ll need to calculate the size of the bag.
I wanted a bag to fit a pot with a 12cm diameter base and a closed length of 40cm.
Decide on the seam widths you will use on the project. I use 1cm seams.
Start with working out the size of the base. In this case, I went for the width of the pot #(12cm) plus an extra centimetre for manoeuvrability, making the finished base 13cm in diameter.
Remember, that you need to allow 2cm extra for seams on a disc. 13 + 2 = 15
Using a bowl, 15cm in diameter, I cut a circle from an old magazine to make the template.
Next you need to calculate the circumference of the circle to ensure you have enough fabric to wrap around the disc to make the tube. This is where those formulae you learnt in maths class finally come useful.
Where C is the circumference, π=3.14159 and on and on, and r is the radius of your circle.
In case you can’t remember, the radius is half the diameter.
And for a sneaky way of calculating, you can of course turn to google where you’ll find a handy calculator if you enter ‘circumference of a circle’ into the search engine.
So in this case, C = 40.84 and I round that up to 41cm and add 2cm for the seams, giving me 43cm wide.
To calculate the length, add 8cm to your desired finished length. This allows for the seam and folding the opening once the bag is filled.
So now we have the measurements needed.
Base of bag (the disc) 15cm in diameter
Body of bag W = 43, L = 48 cm
2 x plastic strips cut from washing up liquid bottle 20cm x 1 cm for stiffening
How to make the DIY dry bag
Fold down a hem of about 2cm of fabric on the top edge and sew to create a slot. Stitch in the middle to create two pockets. These will become the holders for the stiffening strips.
Sew the male and female plastic clips to the webbing, as shown in the image below – one on each end and melt the edge of the webbing with a lighter to stop fraying. Next stitch the webbing to the pocket along the top edge, ensuring the clasps are dangling over the edge and there is clearance to stitch the seams together.
Make cuts (less than the seam allowance) all the way along the edge of the cloth where you’ll attach the base. This will help with attaching to the curved edge. See image below.
Make tacking stitches to position the disc to the main body as shown in the pic below.
Insert a piece of webbing as shown (this helps when removing items from the bag but is an optional extra) and sew around the edge using the sewing machine.
Insert the stiffeners into the top slots, taking care to ensure that they are short enough to allow for the seams.
Sew along the length to close the tube.
That’s it, your bag is complete.
Except it’s not really a dry bag, it’s just a bag! So stick everything inside a giant zip lock or regular plastic carrier bag and the contents will stay dry, unless you plan on going underwater.
To make a fully waterproof dry bag, use heat sealable waterproof material and an iron. The process to create the pattern you need is exactly the same as I’ve described.