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  #11  
Old 12-16-2010
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Okay, but....next stupid question...this technique essentially means you're counteracting the forces on the sails...correct? Couldn't you gain that same advantage (flattening the boat) with trim?

I can definitely see the need on smaller boats...but it just seems like a miniscule counteraction force on a big boat.
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  #12  
Old 12-16-2010
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smack...
Bump your Rep Power and give you another little green box and you go techie on us???
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  #13  
Old 12-16-2010
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I guess it depends on the boat. My current boat's keel weighs more than my C&C 37+ did. The boat doesn't move reguarless of where the crew sit. I went out to watch the boats in the St. Barth's Bucket race last year (must be 100+ feet to enter) and those megayachts had crew on the rail - maybe because it made for better photos.
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Old 12-16-2010
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I'm just trying to get AdamLein to throw down some equations! That dude has the mathematical goods.

I'm convinced there's more to the story here - and I think speciald is right that it's more about the photo than the physics.
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  #15  
Old 12-16-2010
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  #16  
Old 12-16-2010
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Ofcourse, meat resting on a windward bunk would do the same with less windage.

And of course, this is minor compared to small boats. On my first cat we carried two on the trapeeze, on hiking racks. The "rail meat" represented almost 80% of the righting moment. Failure of the rail meat to offset the forces involved were fun.
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Old 12-16-2010
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Quote:
Originally Posted by smackdaddy View Post
Okay, but....next stupid question...this technique essentially means you're counteracting the forces on the sails...correct? Couldn't you gain that same advantage (flattening the boat) with trim?

I can definitely see the need on smaller boats...but it just seems like a miniscule counteraction force on a big boat.


Weather helm is also a function of heel angle. Flattening the boat with railmeat to the optimum heel angle will reduce weather helm when going to weather, without reducing sail area.

When racers do reduce sail area they generally reduce the foresail first rather than reefing the main. That also reduces heel angle and weather helm.

Downwind the boat should be flat.
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Quote:
Originally Posted by smackdaddy View Post
Okay, but....next stupid question...this technique essentially means you're counteracting the forces on the sails...correct? Couldn't you gain that same advantage (flattening the boat) with trim?

I can definitely see the need on smaller boats...but it just seems like a miniscule counteraction force on a big boat.
You can reduce heeling by trimming the sails, or by reducing sail area, but both of those methods reduces the amount of power being generated by the sails. The racer's preference is to keep the sails as powerful as possible, while maximizing the efficiency of the hull and keel. When you use rail meat to flatten the boat, you're improving the efficiency of the hull shape without reducing the power of the sails.

Rail meat accomplishes the same purpose on big boats as on smaller boats. It just takes more bodies on bigger boats. If the boat is heeling excessively when I'm racing, I'll put as many people on the rail as are available, even though they might not be enough. Every little bit helps.

If you have flattened the sails as much as possible, and put all your crew on the rail, and the boat is still heeling too much, then you have to start thinking about reducing sail area.
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Old 12-16-2010
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No offense to anyone, but all the answers are speculative and not quantitative. Sitting on the rail is really doesn't give you much advantage on a large vessel BUT where else should people be? On a properly run boat, people should not be all over the place.... just like on a football field, or basketball court. People have positions and should be there unless they need to be somewhere else. Since the weight has the potential to help, crew and gear should be positioned to keep the boat as flat as possible, if that is how the boat sails best. Like all the other answers, this is speculation without empirical evidence which I'd be really interested in seeing.

On small boats, I see the advantage to keeping the boat heeled in light air - to keep the boom in one place and to keep it from flopping back and forth. Ignoring the mechanics of keeping the boom in place, without exception, everyone that I've asked has not had an answer why the boat should be heeled. It makes no sense, less sail area is exposed to the wind when it's needed most. I'd really like to see a real answer to this since it's puzzled me for years.

On the same note, I question the radical elimination of gear to save weight. I once had crew get on me for carrying 20 gallons of water on an overnight race. One gal of water weighs 8.3 lbs. Then I looked at the guts on my crew......... Hmmmmmmm
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Old 12-16-2010
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There are other ways to flatten the boat then the use of rail meat. One of our friends at the marina has a real sweat racing boat. It's a 30' open with running back stays, full roach main and little to no comforts (doesn't even carry a cooler big enough for more then a six pack). But the boat moves, one day we were making 5.5-6 knots in 7-8 knots of breeze. Just don't take it out in over 12 knots of breeze with out 3-4 people that know what they are doing.

That boat has built in ballast tanks on the under side of the rails that can be filled for short handed sailing. There is a valve system that, with a pull of a line, will gravity dump the water from one tank to the other. It is tricky though. You have to be very quick and precise with tacking or you could knock yourself down and put the rail in the water.

Real fun to sail on that boat for an afternoon, but I'll take our cruiser for the long haul.
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