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-   -   The Physics of Railmeat (https://www.sailnet.com/forums/racing/70692-physics-railmeat.html)

smackdaddy 12-16-2010 10:34 AM

The Physics of Railmeat
 
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So...in thinking about the huge forces acting on a sailboat in higher winds, I began to wonder what the real effectiveness of railmeat is. You've got maybe 1500 pounds on the rail at a pretty weak lever point - trying to counter acts TONS of force on the sail area and keel. Are these guys really making an appreciable difference? Or is this just more tradition than necessity?

What do you think?

imagine2frolic 12-16-2010 10:39 AM

Even if the boat stands up another degree it will sail faster. Racers don't doo anything for nothing!!!!!!!!!!!!!!!!!!!!!!!!!!!!........i2f

jackdale 12-16-2010 11:02 AM

I raced with a UK sailmaker. He would move crew around regularly, inlcuding keeping some on the centreline.

In really light wind you want crew to leeward to heel the boat. That will help keep the boom over and when going to weather a heeled boat is slightly faster.

When going downwind the crew is moved aft to facilitate planning and maintain the boats balance. I have seen fore/aft inclinometers in use.

MSN2Travelers 12-16-2010 11:24 AM

Not just side-to-side trim ...
 
Yup, have to second what jackdale said. Paying close attention to weight distribution does play a huge roll in overall boat speed. We constantly move crew around as conditions and point of sail changes.
Using advice obtained here last winter, our overall performance this last season was much improved. :D Especially noticed during distance races.

AdamLein 12-16-2010 11:53 AM

I have definitely found that shifting everybody to leeward in light winds helps keep the boat moving.

I think another question about people on the weather rail is: does the benefit from keeping the boat slightly more upright exceed the drag due to extra windage?

CapnBilll 12-16-2010 11:53 AM

Your not counteracting those forces, just keeping a small percentage from being lost. If you add just 1 inch per second to the boats overall speed that can add up to several boat lengths over the course of the race.

GeorgeB 12-16-2010 11:57 AM

Smack, rail crew play a critical role in balancing a boat going to windward. They make a big difference. On windy days, we will collect extra guys whose only function is to sit on the boat (and drink beer and eat free sandwiches.) Fleets like the Farr 40 and some of the Jís have restrictions on number of crew members or max crew weights in order to eliminate the advantage of extra crew members. Cruising or sailing shorthanded is at a disadvantage insomuch as they canít trim for speed like a boat with a full crew.

smackdaddy 12-16-2010 11:58 AM

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Quote:

Originally Posted by GeorgeB (Post 677749)
On windy days, we will collect extra guys whose only function is to sit on the boat (and drink beer and eat free sandwiches.)

You do have my number, right?

AdamLein 12-16-2010 12:55 PM

Quote:

Originally Posted by CapnBilll (Post 677748)
If you add just 1 inch per second to the boats overall speed that can add up to several boat lengths

That's 30 feet every six minutes, as a matter of fact.

padean 12-16-2010 12:58 PM

Quote:

Originally Posted by GeorgeB (Post 677749)
Smack, rail crew play a critical role in balancing a boat going to windward. They make a big difference. On windy days, we will collect extra guys whose only function is to sit on the boat (and drink beer and eat free sandwiches.) Fleets like the Farr 40 and some of the Jís have restrictions on number of crew members or max crew weights in order to eliminate the advantage of extra crew members. Cruising or sailing shorthanded is at a disadvantage insomuch as they canít trim for speed like a boat with a full crew.

Besides.... It gives us fat guys something to do and makes us feel important!!!


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