[Public-list] weight distribution/racing

[Meinhold, Michael J]

The quantity that goes up when you fill the tank is the gyradius - directly
related to the rotational moment of inertia. Think of the spinning ice
skater - when she pulls her arms in she's reducing her gyradius.

The thing that slows you down is the added resistance due to your pitching
motion in waves. The more out-of-phase you get with the waves, the more
energy you put into the water. Reducing the gyradius - moving weight toward
amidships - usually reduces added resistance. The pitching motion also
affects your driving force by messing with the flow over the sails. 

It can get complicated because you can get a positive driving force due to
pitch in the right conditions - the winglet-keeled America's Cup boats took
advantage of this.


Mike
Rinn Duin #272
-----Original Message-----
From: public-list-bounces at alberg30.org
[mailto:public-list-bounces at alberg30.org]On Behalf Of Gordon Laco
Sent: Wednesday, March 30, 2005 11:12 AM
To: Alberg 30 Public List -- open to all
Subject: Re: [Public-list] weight distribution/racing


Hi there  -- 

We drain the tank in those circumstances.  Weight forward only helps in very
light conditions and very flat water.  Having the tank full increases the
boat's pitching moment and dramatically slows you down when going into a
head sea.

You would be better advised to do whatever you can to remove weight from the
ends of the boat.

Cheers - Gord #426 Suprise








> Last year, for the big regatta here, the 22 mile race to Daulphin Island
> from Mobile Bay, Al....I purposely filled my water tank (160 pounds
> extra ?) knowing that we were in for a big blow.  My thought was to have
> more weight forward but not too forward.  I also knew my crew wouldn't
> want to be sitting on the rail away from all the action in the cockpit.
> As it turned out we did really well in the race, but I'm still not sure
> if it makes sense to fill the tank.  Anyone have any ideas?
> 
> Patty
> Timbuktu #461
> 
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