Propellers....work it out

[BarryH]

With all this talk about "what size prop do I need" going on at the moment, I spent 10 mins trawling the web and came up with this at <A target="_blank" HREF=http://www.castlemarine.co.uk>http://www.castlemarine.co.uk</A> Have a look at the downloadable prop calc program. Takes about 2 mins to download. Good thing about it is that you can change the variables and get an instant answer.

Putting in the vitals for my boat showed that I am underproped. Helpful seeing as I'm of to pick up the refurb'd prop tomorrow and spend a bit of cash on a stainless one as well. Have a look and see what you think.

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[pheran]

Mustn't complain too loudly as this calculator is, after all, a free download. But it does have severe limitations, not the least of which is the inability to input changes to propellor characteristic eg propellor type (equipoise, turbine......), number of blades, DAR etc. I had bespoke props for my last boat and playing around with the DAR had a significant effect. Still, its a starting point and may at least point you in the right direction. All I'm saying is don't go out and buy propellors on the basis of this calculation alone.

<hr width=100% size=1><font color=blue>A hangover is just the Wrath of Grapes</font color=blue>

 

[BarryH]

Oh god no, would never go and spend money on advise from anything like this. Just put it up there to give a rought starting point.
Talking to my prop peeps this morning. They've been good in advise given. Pointed out, same as the prog, that I'm under proped. They've refurbed my prop and tweeked it my an inch on the pitch. Then they said use that and then see if going to a 19 will give the desired max RPM. From these deductions they'll work out the best stainless one to go for from stock, and tweek either way up or down the give the best performance. What more can I ask!!

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[Bejasus]

Try this one on for size. It is downloadable as an excel spreadsheet.

<A target="_blank" HREF=http://www.arweb.co.uk/argallery/h00>http://www.arweb.co.uk/argallery/h00

 

[chippie]

Thanks Barry I have downloaded it and had a bit of a play with it. I ran some calcs on fitting an auxilliary to a sailing vessel both with and without a reduction gearbox. [Variable pitch prop]. Most helpful.

Cheers.

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