Wouter
You asked for some data to corroborate the claims that carbon masts can be made robust at significantly lighter weight, well here is my 2 cents worth.
We have to date built over 60 F16 carbon masts, we have broken 6.
1 was driven into a pub whilst on it's trailer, 1 was driven over by a car, 1 was broken whilst flying a 21sqm mast head kite, twin trapezing with the main flogging trying to get round a headland, and 2 failed because we built them to a special spec. and the last one had a ridiculous amount of diamond wire tension.
The first masts came from Holland composites, we then bought the mast mould and continued building them to their specifications.
About 18months ago I revisited the spec that we used and came up with a new laminate, the old one was plenty strong enough but I wanted a stiffer mast.
The old spec did indeed have glass in it and there is no reason why this cannot be done, however although glass is cheap, pre-preg glass is not, indeed unless you buy very large quantities it is almost the same price as carbon.
And as you say you can pretty nuch put as nuch as you like in there without effecting stiffness.
Anyway the new mast spec gives a tip weight of 5kg, I just weighed one with diamonds main halyard, and spinnaker halyard in it 5.05kgs.
Purely by coincidence the guy who broke the last mast is a structural composite consultant, he works on very large multis, did Ellens boat and mast, and is doing some giant in Australia at the moment, his credentials are impeccable.
He wanted to ensure that his next mast was stronger and stiffer as he sails with his crew at 190kgs.
He ran the calculations on both our mast specs, the old one had a Euler buckling failure of 1.8 tonnes, and the new one is 3.3 tonnes.
Back to adding glass, the old mast had a significantly thicker wall than the new, carbon is just a hell of a lot stronger that glass, I see no point at all in spending more time putting glass in adding unnecessary cost and weight to a mast that is clearly more than strong enough. I am sure that my customers would not want to pay the extra for a mast that is stronger than it needs to be and heavier than it needs to be, they will simply strap on lead for events that require it and take it off for club racing.
For our mast which has a bigger cross section than the superwing it is a fact that we could reduce the weight and still be strong enough, however the mast would not be stiff enough for our purposes, so it would be slower, so from a strength point in order to get it stiff enough it is overengineered on strength.
You say that stiffness is not an issue since you can adust the cross sectional profile, and you are right, however to do this you need to build a new mould every time, this is not a practical suggestion.
