Volvo Race - the ocean takes over


What is happening now on the Volvo Race ocean course can hardly be called anything other than a smash-up. A shattering of the VO 70 fleet, which has called into question not only the calculations but also the reputation of the designers and builders themselves.

So what is going on? It's all started. Team Sanya...back in Oakland on March 27th, as we've already written about. Events then began to unfold with frightening speed. Two yachts at once - Telefonica и Camper - encountered problems in the bow parts of their boats caused by constant collisions with huge waves - the conditions in the South Pacific are very tough this time. Camper's ramming bulkhead began to fall off the boards - the reason for this may be that the rigid carbon fiber reinforced plastic does not absorb shocks, but serves as an excellent resonator. As a result, the boards gradually start to move away from the glued in between them bulkhead. Of course, such a breakdown is not fatal (though if the boat hit an iceberg or something similar, the lack of a ramming bulkhead would have an immediate impact - and in the worst possible way), but it shows either that the bulkhead was not glued well or that the calculation of side vibration was wrong (in this case the situation is particularly puzzling because not only the bulkhead is peeling off the boards but also that it breaks on its own).

The second, in our opinion, is more correct at least because such careful calculations in yachtbuilding are extremely rare - not aviation. Yes, they are done, but usually not without a sleeve. Why would you build a hull with such calculations, if it will be used for one regatta? For the second one, if someone will buy it, it will have to be seriously modified and modernized. So there is no need to bother.

Therefore there is experimentation by trial and error, no matter how cynical it may sound.

Once such experimentation cost very dearly to the class of 60 foot trimarans - raging Atlantic killed all their fleet in less than a week, and the class never recovered from this blow. (Note that designers and builders of our Orca in the last VOR race used kevlar honeycomb instead of nomex in the most strained places - yes, more expensive and a little heavier, but the Orca, at least, didn't break).

One may also recall the first breakdown of Orange II The cause of the plastic splitting in the bows of both hulls was exactly the same - resonance and incorrectly selected rigidity of the foam filler, because the vibration calculation of the boards was not done (in this case the Orange II designerGilles Ollier admitted it directly).

And now exactly the same failure was reported on Telefonica, the leader of the race: delamination of boards at bow. The reason of it is (excuse engineering reasons) that because of different rigidity of carbon fiberboard shell and its filler (usually nomex honeycomb) the carbon fiberboard and the filler deform differently when waves hit the shell. Difference in frequency of natural vibrations tears off the plastic from the filler (and the rules of yacht building of VO 70 class now forbid the use of resins with polymerization temperature higher than 90°С, having especially high strength and toughness of the connection).

Conclusion: Telefonica with patches of spare battens applied (pun intended!) goes to Ushuaia for repairs, Camper to Puerto Montt. But that's not all. Just a few hours ago we got a message that yacht Abu Dhabi broke down onboard the fourth yacht in the series. The reason is the same: delamination of the hull at the bow. PUMA and Groupama are the only two yachts left in the range.

Only one third of the fleet is still in the race, an unprecedented case.

Gentlemen designers! After all, the last race in 2008-2009 showed that the longitudinal stiffness of the VO 70 hulls is clearly insufficient. During the fourth stage of the East China Sea race this defect was revealed with the utmost cynicism - on one of the Erikson ships they even had to cut out a damaged piece of the hull in the prow.
Fair enough, the designers (and class rule-makers) were not at all oblivious of the lesson. However, this time the yachts lasted for a month longer before starting to fall apart. And in the race of 2005-2006, one of the boats even sank.
Progress is evident!

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