There’s a reason it crashed

Did you see the cat crash in San Francisco [h/t/ Rossa]?

For a start, these people are right out there on the edge, i.e. they are sailing to the limit.   Poor design from inexperience in multihulls compounds that and the third factor is the conditions.   San Francisco Bay is notorious for its tides and choppy waves:

The design problem is the bow.   The new bows use an upside down configuration with the sharp part above and the fat side down – theory is that the buoyancy kicks in earlier, keeping the bow up and piercing the wave[s] but there are two things:

1.  If there is a tide and short chop, plus the boat suddenly accelerates, as in bearing off and sailing on the edge, the bow only need go into one wave and it skewers downwards.   Now it will come back up once the buoyancy kicks in unless:

2.  They’ve pared away the buoyancy in the interests of finer bows and therefore speed but also less buoyancy up front.

Accident waiting to occur.   These cats have not been an unqualified success because they are being built and sailed by non-cat people.   Real cat people build their boats like Cogito, bows slightly up in the air and it doesn’t happen:

You’ll notice they also don’t try to apply a jib to the wing.   Look at this pronounced bow up configuration in Airbus [the British boat]:

It’s true that Oracle, with its inverted bows, is faster by a fraction and that is what counts in racing these things but as they have just shown – no point being half a knot faster when it’s odds on you’re going to submarine.

You’ll recall a post earlier here in which I showed pics at the top of bow-up configurations – those were the forerunners of the pics above here.   They never nosedived.

My suggestion, not that anyone ever listens to me, is that they sail the race in the AC45s they’ve been practising with.   They’ve just about got the hang of those.  The 72 is a whole new beast.

One Response to “There’s a reason it crashed”

  1. haiku October 19, 2012 at 12:11 Permalink

    Irrespective of the technicalities (outlined above) the San Francisco Bay is not the best of places to push both your new boat and your luck.

    A number of years back I had the pleasure of spending the day on the San Francisco Bay: not on a catamaran but on a 40′ twin-diesel ex admiral’s barge

    Apart from the tides and the choppy waves, the weather changed more frequently than it does in London on a summer’s day: in the matter of a couple of hours we experienced brilliant (and hot) sunshine, fog and overcast / pouring rain.

    BTW, not due to changing weather conditions: the Bay has most all weather conditions simultaneously. Only the exact location changes …

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