Propeller calculations...

[RonW]

http://boatpropellers.com/propcalc.html

Punch in numbers and learn or get more confused.

See if you can figure out a prop with no slippage.

[ssor]

They're bound to slip some, But if the dia. is large enough, the pitch great enough, a large enough blade area and the rotational speed low enough, the slip will be minimal. BUT the propeller will probably sink the boat!!! :D

[ 02-23-2005, 08:01 PM: Message edited by: ssor ]

[Lucky Luke]

No, it will not sink the boat: when the prop turns one way, the boat will turn the other way :D

[Stan Derelian]

What is tolerable slippage? Is there a range of values?

[ssor]

Dave Gerr, states typical slip values range from 45% on sailboats and barges running at less than 9 knots to as little as 7 %in stepped hydroplanes running at 90 knots and above.
editted to add:
On my auxillary sloop I run a 13x15 three blade propeller at about 900 rpm to get 6.5 knots. I have a 3:1 reduction gear and ten HP.

[ 02-25-2005, 03:26 PM: Message edited by: ssor ]

[paladin]

fuel economy is a 44 foot boat with a 46 gallon fuel tank...and after three years of adding anti slime additives you pump out 30 gallons of fuel, scrub the tanks and lines...and buy new fuel....

[ssor]

Paladin, and people wonder why I installed a ten gallon tank and carry spare fuel in a six gallon can on deck. :D

Ross in Bel Air, Md