Sunday, April 27, 2014

WHY BERNARD STAMM's OPEN60 BROKE IN TWO


Finally some answers and unsuspected ones: The boat was not badly designed (it was  not too weak) and a previous boat repair was not the origin of the breakage. As strangely as it seems the problem on this carbon boat had to do with aluminum electrolysis and aluminium degradation.

Stamm's boat, a  JK design, used an unusual technique in what regards the core material on that carbon hull:  aluminium honeycomb. Almost all other boats use a carbon honeycomb as core (Nomex). The aluminium core was used on some Class America boats and also on the America's cup BMW/Oracle.
It seems that using that kind of core has some risks since the carbon is a very good electric conductor. All evidence points to the passage of an electric current that provoked an electrolysis and destroyed p'art of the core. There are zones that are impeccable and others completely destroyed.

It seems that after all the salvage of part of the hull was essential to know why that boat had break in conditions that were less demanding then many others that it had experienced before. For the ones that did not follow, they were in stormy conditions but not pushing the boat, on a delivery trip.

 It seems to me that given the extensive sailing program of those boats, namely non stop circumnavigations, that type of core should be banned from the IMOCA class: too many situations were an electric current can find its way to the  aluminium core on a Carbon boat.

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