Prop size

[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

 

[Guest]

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

 

[Guest]

Download calculation program

Castle marine's software can be downloaded from: http://www.castlemarine.co.uk/pitch.htm

 

[Guest]

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

 

[Guest]

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!