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Thread ID: 117907	2011-05-10 08:16:00	Any boat experts here?	prefect (6291)	PC World Chat

Post ID	Timestamp	Content	User
1201053	2011-05-10 08:16:00	There is some law about the length of displacement hulls only achieving a certain max speed irrespective of engine power. I went in seagull race at Easter on a catmaran the second engine made the boat go slower as it dragged the back down. about 12 mph with 1 engine and 10.5 with 2. Didnt try flashing the third one up. Next year will put the engines on the front and try it. Question how do you get the hull length in the formula for a cat?	prefect (6291)
1201054	2011-05-10 10:53:00	I'm hardly an expert but I understand you combine the hulls to get the length, so a 10m cat is the equivalent of 20m, and longer is better.	Ofthesea (14129)
1201055	2011-05-10 11:37:00	Monohulls are hull speed in knots =1.3 √waterline length in feet. Multihulls don't seem to have the same limitations. Just overpower them until they flip.	nerd89 (14761)
1201056	2011-05-11 00:07:00	Monohulls are hull speed in knots =1.3 √waterline length in feet. Multihulls don't seem to have the same limitations. Just overpower them until they flip. Actually it is 1.6x sq root of waterline length in feet (knots) and that formula relates to the maximum sailing speed to windward to a yacht under sail. With a powerboat there is a law of diminishing returns for horsepower in relation to propellor pitch, there is a limit to the amount of thrust a particular propellor can produce before cavitation sets in and kills efficiency. The other factor that comes into play is whether the hull is a displacement type, or whether the boat is planing. More power is required to get a hull onto the plane than maintain it once it is there.	KenESmith (6287)
1201057	2011-05-11 00:17:00	Actually it is 1.6x sq root of waterline length in feet (knots) and that formula relates to the maximum sailing speed to windward to a yacht under sail. With a powerboat there is a law of diminishing returns for horsepower in relation to propellor pitch, there is a limit to the amount of thrust a particular propellor can produce before cavitation sets in and kills efficiency. The other factor that comes into play is whether the hull is a displacement type, or whether the boat is planing. More power is required to get a hull onto the plane than maintain it once it is there. It isnt ever going to plane powered by the 4.5 hp seagull. A guy told me at the race for displacement hulls the length of the boat equals how fast you can go if you add more power the boat wont go any faster but will drive itself into the water and sink. I just want to know how the rule applies to catamaran got it sorted for mono hull. The race has been going since 1984 and I am supposedly the first three engine boat but it went faster on 1 engine. Future plan will involve 6 seagulls powerheads in a ring with a fanbelt and centrifugal clutches for each engine and drive it like those riverboats in Thailand ie a motor on a stick.	prefect (6291)
1201058	2011-05-11 00:49:00	It isnt ever going to plane powered by the 4 . 5 hp seagull . A guy told me at the race for displacement hulls the length of the boat equals how fast you can go if you add more power the boat wont go any faster but will drive itself into the water and sink . Been there - done it! I have a 1946 12 foot Douglas Aircraft aluminum boat and one day I got tired of the 2 . 2 HP 2-cycle putt-putt on it and put my 15 HP Mercury on it . The faster the engine ran - the lower the boat got in the water until I had about one inch of freeboard . 'Now what?" I asked myself - visions of being swamped by the stern wake returning over the tumblehome and me swimming to shore, trying to carry my Merc outboard engine . SOMEHOW - I just released the throttle and kicked the tiller all the way to the left (or right - it really didn't matter at that point I think) and the boat instantly stopped and it popped back up to full floatation . Whew! I was quite relieved and s-l-o-w-l-y putted back to the launch ramp and put the lil' guy back on .	SurferJoe46 (51)
1201059	2011-05-13 04:08:00	picasaweb.google.com Me crashing into the safety boat. The rudders didnt deflect much and need to be bigger. Didnt think it would be a problem but the water out of the turbines is swirly. picasaweb.google.com Second day going well then run aground on sandbar at mercer jumped out to push went up to my neck in quicksand and that was end of nokia mobile fone. 2 motors to go on front next time and 1 on the back, will put a pump in the hulls for bilge water, rudders to deflect to almost 90 deg instead of 20 and treble the size. Also will build a bbq like Australian had on his boat he gave me a sausage when I passed him at Hamilton. He must have been on something because he was singing as I passed him. Last year the characters were from Bermuda never seen a person put away as much rum as those Bermudans and I was sick the next day trying to keep up with them.	prefect (6291)
1201060	2011-05-13 04:29:00	I looked at all your pictures. A question? 'Waikato' --- is it pronounced 'wah-eee-kaht-o' ? Youse guys speek funni.	SurferJoe46 (51)
1201061	2011-05-13 04:30:00	pronounced why cat o o as in oh is that a bear rushing to attack us as opposed to a zero or nought pronunciation. If you think you can pronounce moaris try this one Onehunga pronounced o knee hung a not number one hunga Then final test Whangerai Wong ger ray	prefect (6291)
1201062	2011-05-13 04:39:00	pronounced why cat o o as in oh is that a bear rushing to attack us as opposed to a zero or nought pronunciation. If you think you can pronounce moaris try this one Onehunga pronounced o knee hung a not number one hunga Then final test Whangerai Wong ger ray C'mon - tell the truth - youse guys ain't got no bears! Right? I'd worry 'bout dem meat eatin' parrots though.	SurferJoe46 (51)
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