BoatBanter.com - View Single Post - Any thoughts onhow to make this boat better

In article ,
says...

"Dave Doe" wrote in message
. nz...
In article ,
says...
OK, Duncan. here's a little experiment you can do in your
bathtub.

1. Put an empty Coke bottle in the water. Observe how it
floats.
2. Fill the Coke bottle 1/4 with water. Observe how it
floats.
3. Fill the bottle 1/2 way. Observe how it floats
4. Fill it 3/4 full. Observe how it floats
5. Is the water in the coke bottle below the tub water
surface?
6. Wash your butt last.

Scotty

a) What is the *point* of your experiement? - other than to
only prove
my argument correct.

To prove to you that water BELOW the water line can still act as
ballast.

Indeed it can and I have not questioned that, only it's effectiveness as
not just ballast, which I have stated provides a positive stability
factor - but I question its effectiveness when used as a righting
moment. And further posed the question:

How much water ballast (approx litres) does it take to equal say
200lbs of lead hanging 6' down (on say a swing keel)?

To make it easier, how about we metricate it all for ease of
calculation:

Assume Standard Temp & Pressure (STP)
How much fresh water (density: 1000kg/m3) does it take to equal 500kg of
lead (density: 7140kg/m3) hanging 2m down with the boat at 45deg? Water
ballast tank at 1m wide and the boat is in fresh water (also at STP).

Feel free to use other figures, I've adjusted from my original, using
hopefully more "average" figures and rounded to make calcs easier.

So how much water?

And... looking at say a Mac, they say they have 1150lbs of water
ballast, that's about 520kg.

You change the figures if you think mine are unrealistic - I'd just like
to see the comparision.

PS: only got to sail against a Mac 26M once out in Lytellton; my boat's
just under 25' - the Mac is 26'. We thrashed it. (They might be quite
competative in light air; 5knts or below). My boat's 23? years old, the
Mac is less than 1. It's longer.

--
Duncan