Dario's Lab

Octave Marblehead Prototype Rigs: Boom Elbows

This is one solution for M class booms.
A bit labour intensive but light and stiff.
The balsa core in the elbow could be replaced with foam though arguably using balsa offers toughness.
There is possibly a windage advantage in round booms, and our experience shows this to outweigh the downwind projected area and end-plate effect of flat-sided main booms. Using round tubes allows a family of rigging solutions not possible with foam sandwich or box shaped booms.
The geometry is dictated by the foot round, following the deck as far aft as possible, then kicking up to meet the mainsail clew.
The booms step down in diametre at the joint. The joint is reinforced with carbon sock slipped into position then wet out with epoxy resin.