Hello Hans,
... I see for some reason that Wouter is anti carbon and he is an alu fetish ...
My boat has :
ply hulls
epoxy resin and glass tape as joints, with some carbon and kevlar local reinforcements
aluminium mast and beams
carbon laminate rudder boards and stocks
Glass vinylester daggerboards
stainless steel dolphinstriker, stays and mast/beam fittings
dyneema trapeze wires.
I can be accused of many things, but not of anti-carbon or alu-fetish tendencies.
It is as I always said. Look at the individual design problems in detail and choose the best material for that application.
Sometimes this is carbon, other times this is aluminium at other times it is something else.
but i have to say that the boom he did designed will be working but you will never been hit by this shape because the damage would be severe.
Agreed, this was a quick knock-up of a design. I have an idea of how to make one that is less hurtful when hit. It is a little more complicated and I didn't have time to work that one out fully, including drawings etc.
I'm probably going to propose that design to Gato for his mini650. Roughly speaking it is a round section made from straight planks that has been routed and sanded to have round sides. the flat top and bottom planes will take the carbon cloth or aluminium strips to get it up to sufficient strength and stiffness. This building method, but without the carbon or alu, is indeed used to produce lightweight timber round spars for masts and booms on traditional Dutch sailing boats.
Wait a minute; I have a document somewhere I written in 1999 or so ...
Wouter
