Prop size

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Guest

Guest
Can someone give me a formula for calculating the size of propeller needed? I run a Scow that is as follows: Steel 10 ton 32 ft LOA 28 ft LAWL Engine: MWM 33HP @ 1800 (two cylinder diesel) Gear ratio: 3:1 Prop: 21 x 15 three blade bronze on 1.5 inch shaft

Any help much appreciated

Thanks

Kim
 
Pitch and dia. too small at present?

Kim,

My version of “Propcalc.exe” from Castle Marine (01286 674 322) quotes 25 ½ inch diameter, with 25 ¾ inch pitch, however there is a warning that this shaft speed is unsuited to the hull type?

You could also take a look at:-

http://www.surfbaud.co.uk/~wave/surfprop/index.html

For a down-loadable Excel spreadsheet, which may help you to work this out for yourself.

Also try looking at:-

http://www.go-fast.com/Prop_Slip_Calculator.htm

Cheers, CRB
 
Re: Pitch and dia. too small at present?

Excellent advice. Both calculators provide similar results. Ratio of 2:1 gearbox would prove beneficial.

Thanks Kim
 
Glad to be of service!

Thanks also to Vyv for the URL, I had the S/Ware, but couldn't remember where I got it from.

Good luck!
 
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