Welcome! Need support, you got it. Or share you ideas and experiences.
In Reply to: Re: a hypitheticaly stupid question posted by machnumber2 on March 02, 2003 at 22:38:59:
oops I think i spotted at least one error above, 5mph is not 11.2 m/s it is 2.2 m/s.
p = 446 newtons * 2.2 m/s
p = approx 1000 nm/s a newton meter is a joule, 1000 joules is a kj, a joule per second is a watt
p = 1 kj/s = 1000 watts
there are .746 hp in 1000 watts
I knew i should have been looking at the girls paper next to me in algebra rather then down her blouse ;P
Ken, the easy answer is you need 1 horsepower for every 27.5 pounds of weight. 200 pounds would need 7.27 horsepower to launch and plane. add the weight of the boat motor and another person and this is where the extra hp. comes in, example boat=400lb. skier =200lb. motor =155lb. driver=200lb. You now have to move 955lb. from dead stop to plane on calm water. Theoretically you need 34.72hp minumum.Top speed is not a revelant issue here. There are simply too many variables to be discussed here to even determine what top speed would be. A skier will stay on plane at as little as 2.5 mph. this is the same as a brisk walking pace. Inertia and other factors help maintain the conditions needed for planing.,TG.
Too much thinking involved for me!
All I can say is that I learned to ski behind a 35hp on a 15' Lund. It pulled me up on one ski when I weighed about 130lbs. I could still ski behind it at about 165lbs. I'd get up on 2 & drop 1 right away.
Last time I tried on that setup was about 185lbs. It took a lot of arm strength to pull me up & it took a while to do! When I did get up, I needed to cut to get any speed, but by doing this, it slowed the boat waaaay down!
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