Wood-fiberglass Mast (ideas to improve it in 2022?)

[rxcomposite]

You mentioned in one of your post that the mast made is 250 x 750 mm. This appears to be like a symmetrical airfoil shape. In all the pics shown, it seems more like a "goldfish" shape profile. In the variance of the pics shown ranging from Kurt to Eric. note that the construction is a solution to the cross section.

Round or rectangular section do not need a web because the moment of inertia is high, As you flatten it, you need a web to tie up the upper and lower skin plus a web for the leading and trailing edge to take care of the shear flow. If the main web/ribs is too tall and exceeds the shear requirements, lightening holes are cut out.

Now, what is the profile dimension/shape you want or going to build is to be evaluated? What deflection are you expecting based on the RM with a 20 meter mast? If you don't have any expectations, we will be running around chasing numbers.

The specs based on the drawing (hard to read) is 18,828 ft.lbs RM with a displacement of 11,600 lbs, and the mast is fixed (or rotating) at the deck. Correct?

 

[wet feet]

I'd be a bit surprised if the mast in post #30 would actually rotate.Unless the rigging attachment points are in the same axis,the mast will be constrained in it's freedom to move and the loads may be increased by fighting the torsional loads.I would also expect the lower shrouds to be more or less co-planar with the cap shrouds to resist deflection in that plane.Runners to resist a change of rake ought to be led well aft on a conventional monohull,but a catamaran may have the inherent speed to keep the apparent wind far enough forward to not depend on their presence.What does the designer specify?