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AC72 capsize
Team McLube



Oct 18, 2012, 5:07 AM

Post #1 of 3 (9227 views)
AC72 capsize Log-In to Post/Reply

Take a closer look at the video of the Oracle 17 capsize

Did a chase boat prevent a deeper turn and cause the capsize?


Oct 23, 2012, 2:00 PM

Post #2 of 3 (9184 views)
Re: [jackQ] AC72 capsize [In reply to] Log-In to Post/Reply

I have watched the video back and forth multiple times and do not see any problem with the chase boat(s) as both pass rear of Oracle 17 but I do find some other details.

When Oracle 17 is going in to the turn the leeward hull bow is in the water and the windward in the air (which makes sense).
Please note how this changes where the windward hull bow dips in the water while the leeward hull is pointing up. Freeze the film 0:05-0:06 and notice the big difference in hull angel against each other. This is flexing in the beams that allows one hull pitch down without getting flotation from the other hull. Please note how only the portside hull dives down in the water while the leeward hull has the bow in the air 0:10 and forward.
There is also an excellent still picture that illustrates the beam flex that allows one hull to pitch.!i=2155184161&k=FfTNzFP&lb=1&s=A
(picture #6 of 164)
Fair enough - the leeward hull is up on the L-shaped foil and not the other one but this do not affect the visible angle between the hulls only if the hull is lifted or not.
Fair enough 2 I did not say it would be easy to build a stiff boat of this size just because Im pointing out some weak points (!). But I do think the stiffness is just as important as hull volume in this matter.
I sail Tornado myself and started off with an old Sailcraft that pitched down one hull when you where pushing it to hard in strong winds. I then swished to a autoclave-built ultra stiff Marstrom boat and its like a complete different boat without this problem. I think the AC-teams should give Goran Marsrom who learned to build cats by experience a call instead of relying on their computer design all the way Smile



Nov 1, 2012, 2:45 AM

Post #3 of 3 (9084 views)
Re: [jackQ] AC72 capsize [In reply to] Log-In to Post/Reply

Someone needs to say this.
The AC72 pitchpoled because it is simply unseaworthy. There is nowhere near enough volume up forward to counteract the drive of the wing and convert it into forward speed.
Instead, in relatively flat conditions, the hull(s) are simply driven downwards into the water, and the wing flies straight over, causing the pitchpole.
We have seen the same thing on the AC45s and it will keep on happening. Every Hobie 16 sailor knows this.
I hope no one gets seriously injured or killed during one of these embarrassing failures.
These boats are unworthy of America's Cup.

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