Simpler Wooden Mast

Here’s an idea for a simpler wooden mast:

ItemHeight above heel (m)Notes
Heel060×60 square
Partners0.5790×70 rectangular
Boom0.9380×70 rectangular
Square1.570×70 square
Circle base2.470 diameter
Top5.640 diameter

This mast uses rectangular sections at the base to provide the strength. It gradulally transitions to square section, then circular sections when possible. The rectangular and square sections next to the sail aren’t ideal – the junk rig works better on a circular section mast as this allows the sail to rotate freely. However this design would be easier to make.

I’m not going to show the strength calculations here. If you want more detail please ask!

Weight isn’t too bad. Adding up the weight of each mast section we end up with 10.3kg.

More on Aluminium Tube Masts

A couple of extra points:

Suppliers

Finding suppliers for tubes that will definitely fit is proving harder than I expected. In particular I’d like a 70mm diameter by 3mm wall thickness tube for the main tube, as this should fit a 2 1/2″ inner tube with everything at its nominal size. However 70mm is very close to 2 3/4″ so 70mm is hard to find.

I’m also struggling to find suppliers who will measure what they have in stock.

Adjusting the size

I found a discussion on using Car Exhaust Tailpipe Expanders to adjust the size of an aluminium tube. Neat idea but rather scary – I’m not sure what that would do to an aluminium extrusion with a T6 temper.

However:

  • It might be possible to make the internal diameter 0.1mm larger, should that be necessary;
  • I could always wrap abrasive paper around the tool and use it to make the internal diameter larger using an electric drill on low speed.