The Benefits Of Carbon Fibre Masts

Pictures of Americas Cup-class boat hulls breaking in half and their masts, supported by a plethora of rigging and spreaders, collapsing in relatively benign conditions, have given structures built of carbon fibre an undeserved reputation for fragility. But it should be remembered that Americas Cup boats are designed on the ragged edge of structural engineering where the motto is “if it does not break occasionally, we built it too heavy”.

Tuning the new rig

The facts are that a cruising mast properly engineered and built in carbon is stronger, stiffer and less susceptible to fatigue than a mast built in aluminum could ever be. And all this at about half the tube weight of an aluminum mast.

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John, When we met in Charleston you mentioned once in to me that your rigging size had remained the same (or even increased?) when changing from Aluminum to a Carbon mast. So the total weight savings in a change from Aluminum to Carbon mast is “only” in the actual mast and NOT in the rigging. Is that correct or did I misunderstood you?

I am not too familiar with carbon, but I guess due to the increased acceleration forces by using a carbon mast the rigging size has to be increased (or remains the same when changing from Aluminum to carbon, bus as weight decreases of mast you can say rigging weight % wise increases.)

How did Mast Weight versus rigging Weight compare on Morgans Cloud with Carbon?

Geoff Jenkins

I’m sold onthe benefits of a carbon mastfor all the reasons discussed, the one question I have is how one assesses the potential damage caused by a lightening strike, as unlikely as a strike might be. The carbon spare is basically a long resistor and there will be significant heat build-up during a strike causing any resin-trapped air to expand and possibly cause fractures. Does a grounding wire sufficiently shunt and protect the mast in such situations?

Geoff Jenkins

Daniel Wolff


I understand that you didn’t replace the boom with a carbon boom, since yours was still very usable. But if you were to spec a new boat, would you spend the money on getting a carbon boom as well?


The Alloy mast was replaced after 25 years and 120,000 miles. Replacing like-for-like would have cost $30k. This gives $1,200 per year or $0.25c per mile. How long is the $55k carbon replacement expected to last?

P D Squire

Do you think a carbon mast could also reduce drag aloft? Perhaps it can be made thinner for the same strength. This would seem to initiate another virtuous circle in terms of windward ability. When reefed down and clawing off a lee shore it would seem advantageous to have a skinny needle aloft rather than a relatively fat pole.

P D Squire

Please delete this comment. You’ve already answered it. And I’m getting forgetful.