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September 20th

2013 AMERICA’S CUP FINALS: Backs to the Wall

Posted by // September 20, 2013 // COMMENT (0 Comments)

Racing,

We’re hard on it, sports fans. The Oracle boys dropped a hard-fought race on Wednesday (two lead changes, plus a big surge on the last downwind leg) and now can’t afford to drop any more. One more win and Team New Zealand will be taking our tin back to Auckland. Oracle did what they had to do yesterday to stay alive–slam-dunked the Kiwis at the start and led all the way to the finish line. Check out their speed upwind in that viddy up there. Full foiling action with top speeds over 30 knots. They just keep getting better!

I’m holding my breath: how much longer can they drag this out???

Here’s the replay of Wednesday’s race down here:

Both days the second races were cancelled as wind speeds on San Francisco Bay exceeded the wind limits set for “safe” racing. A ripe topic for carping and complaining among the peanut gallery, as you might imagine. Personally, I think this helps Oracle in their bid to come from way way way behind (they’re down 8-2 on points and now need seven consecutive wins to keep the Cup), as it gives them more time to tweak and pray in between each race.

The best place to follow the carping and complaining, of course, is over at Sailing Anarchy. Some of it seems incredibly well informed. Here’s one very interesting comment from one RHough:

I cracked the books a bit and ran some numbers yesterday. I think I have a good reason for the wind speed limit being set where it is. Wow was I wrong.

The boats ended up being faster than they predicted, i.e. the designs were too good. :-) This put them dangerously close to putting the foils into cavitation speeds (~50+) that could have lead to real control problems.

Basically they want to limit boat speed to under 50 knots to stay safely out of foil cavitation speeds. The boats can sail over 2x wind speed and in some ranges are close to or at 3x wind speed the TWS needed to keep them below 50 knots is in the 22-24 knot range.

The wind limit for safety was not a reaction to the Artemis disaster as I assumed incorrectly. I had assumed the limit was for structural concerns not an unforeseen design challenge.

If they want higher wind speed limits they have to lose the foiling to remove the “50 knot barrier” or they can lose the wing to reduce the top speed of the boats to under 3x wind speed.

If they want to keep the full foiling and hard wings they are stuck with a low wind speed limit until they solve the cavitation issue. Sort of ironic that the faster the boat is relative to wind speed the lower the safe wind speed becomes. If indeed the wind limit was lowered due to concerns about foil cavitation then they got it right and the engineering math supports it.

It is not about being pansies, or poor design, or reaction to the Artemis disaster. It is about unforeseen design success.

Stop bitching about the boats being to fragile to sail in 30+
Start celebrating that they are too fast to sail in over 25.

 

And another from one catsailordude:

The wind limits are definitely necessary but the way they are applied has caused a great deal of disappointment for the viewers. It’s unfortunate that a race can be cancelled during the pre-start because of a 15 second gust. Given that the races last only 20 minutes or so, I think that once the pre-start has commence (at 2:10) there should be no cancellations. The wind limits should have had some cushion built into them to allow for the fact that wind could increase by a knot or two during a 20 minute race.

As for anyone being pussies, people sailing non-self-righting boats that foil at over 40 knots are not pussies. Sailing a fast boat in 12 knots TWS is much more on-the-edge than sailing a ballasted boat in anything. Calling these guys pussies would be like calling an F1 driver a pussy because he only drives on smooth pavement and doesn’t go off-roading.

The mistake of this America’s Cup is not that it’s in fast catamarans, it’s that the rig is just a little bit too tall for the conditions of San Francisco. Had they gone with the 110 foot rig, the boats would have less weight and power up high and the wind limit could have been set at 25 or 26 knots, which would have meant few if any cancellations. It also might have meant that you would see the code zeros come out in 12 knots instead of 9 knots. Hopefully ETNZ runs the next cup in catamarans, but with a rule that is more accurately calibrated to the prevailing local conditions.

But this is only version 1 of this type of boat in the Americas Cup and despite a few cancelled races, this is by far the best sailboat racing I have ever seen broadcast, and not just because of the speed–it’s more because the upwind legs. It is certainly much better racing than anything we saw in 1992 or 1958. Let’s face it, the only competitive America’s Cup finals prior to this one were in 1983 and 2007.

Even with the 131 foot rig, these boats and crews are handling the big breeze better than just about any AC boats in the past. They are certainly handling the breeze much better than any prior AC boat capable of powering up in 6 knots of wind.

 

You can read the whole conversation at the SA forum thread Absolutely Pathetic.

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