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Any thoughts onhow to make this boat better
"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. Also , to wash some of the stink off of you. Scotty |
#3
posted to alt.sailing.asa
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Any thoughts onhow to make this boat better
"Dave Doe" wrote in message . nz... 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 My understanding is that the Macs have an optimal window of between 7-10 kts.wind, they will hardly move in light air. Tiny rig and sailplan. Have seen a rating for the old 26X at 226, IIRC, but I'm willing to bet that it's very tough to sail anywhere near it's rating. Anecdotal, but I was sailing back to the marina one day, playing with the a-sail, and I passed an x that didn't appear to be moving, my knotmeter was reading 3-4 kts, maybe around 5 kts.of wind. John Cairns |
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