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post #50 of Old 01-08-2011
Jeff_H
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Taking Sailing World's comments in the context of the article, and my comments in the context of this discussion, I would suggest that we actually are more in agreement than not. I would also suggest that any apparent discrepancy between the Sailing World quote and the discussion above is a more about these not being nuanced discussions than being any disagreement.

As I read the quote from Sailing World, it is saying that as a boat heels the center of gravity of the crews weight shifts closer to the center line of the boat, and therefore is less effective than when the boat is flat. If I consider that point taken isolation, I have no disagreement with that. What it does not discuss, and which is outside the scope of the article, is that as most modern boats heel, the center of buoyancy moves to leeward and so although the center of gravity of the crew weight moves toward the centerline, the impact on righting moment may actually stay the same or increase up to some point of heeling angle.

At some angle of heel, the center of buoyancy begins moving back toward the center of gravity of the crew and so the crew's impact drops considerably.

I also completely agree with their statement, "In other words, it may be more effective to depower the sails to flatten the boat than to have the entire crew exhausting themselves."

Allowing a boat to heel potentially has a series of negative effects on performance (increased leeway, increased weather helm (and so more drag from steering to counter act), larger tip vortexes on the underwater foils and so on.). To some extent, these negatives are at least in part offset by having more drive from the sails. Up to a point, this greater drive results in better performance by overcoming the greater drag and leeway from heeling. But after that point, performance drops off as the amount of drive ceases to increase but drag continues to increase.

What the Sailing World sentence is saying is that instead of over-powering-up the boat and having your crew wear themselves out hiking, you may actually have better performance by depowering some and sailing flatter. The key word in the Sailing World quote is the word "may", which I marked in bold for emphasis, since it will be up to the skipper and crew to find that point and stay at or near it as much of the time as they can. If the boat spends a bunch of time way above or below that heel angle relative to their competition, they will end up reading a whole bunch of hailing ports.

It does not take a genius to see that, but somehow you missed it.

Jeff


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Last edited by Jeff_H; 01-08-2011 at 05:37 PM.
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