Choosing the right prop.

[Ratty and Moley]

How do you work out what prop is best for your boat/engine?

We know of a Tod that threw hers a while back and was wondering what would be the prop to have her refitted with. (She's a VERY early Tuna with inboard motor - not sure what exactly - You don't hear much of them as a type really do you?)

Also how do you work out the pitch?

MTIA

R&M

 

[jfm]

You can pick a similar boat and copy; go by gut feel and educated guess; or use a software program to compute it if you have all the boat's data

The dimension to get right is pitch. Diameter isn't such a fine science, and anyway the thing has to fit physically

Poster GrowingLad on this forum has a Todd Tuna (I think...). It has an inboard. So her might be able to tell you his prop size

 

[MapisM]

Also how do you work out the pitch?

Just post these figures if you know them, and we can give you a reasonably accurate answer:
- max speed the boat is supposed to achieve;
- max engine(s) RPM;
- gearbox ratio.

Other than that, there are three ways to determine the proper prop/pitch: test, test, test.

 

[Ratty and Moley]

Thanks for all the info and help. We will try to find out and go from there.

In the mean time our time is being spent on our current challenge the mysterious "Pearl White" Clicky for blog

 

[Tranona]

Use the Propcalc programme on www.castlemarine.co.uk to get a useful starting point.

 

[Lewis 53]

Google "Crowthers Marine" and phone them. They are a Manchester based specialist company that specialise in this sort of thing. I have used them and can say they were really helpful and sorted my problem. Usual disclaimer... I have no connection with them other than a satisfied customer.
Lewis