Tube template (help!)

[gbftats]

Hello everyone, So I was recently given an old boat. The tubes are shot but I figured I could use them as a template to make some new ones. After taking it apart I realized the fabric is pretty stretched and I dont think It is going to give me an accurate template. At this point I think it will be more beneficial for me to just make new templates and start from scratch.

however the problem I am running into is at the bends in the tubes. They are obviously cut in an S curve to avoid the hard V you get if I was to cut the fabric folded in half and cut at my desired angle.

So my question is, what is the process of calculating the S curve shape on the fabric to correspond to the angle of the bend in the tube so everything lines up and fits correctly when its time to glue?

Pictures included, feel free to DM or email me if needed.

[Dave Cowell]

You will probably find that the material hasnt stretched as much at the joints as there will be double or triple thicness fabric at those points depending upon the joint construction.
Measure the width of the panel at the joints and mid point and calaculate the diameter to see how it compares to the diameter you want on the new tubes.
You may find you can use curves on the existing panels as templates for the curves you need.