Prop selection

[A1an]

I'm in the middle of doing up an old Yam 60 2 cyl.


It's going to go on the back of a 15ft cathedral hull.

Any ideas where I should start with pitch?

[Locozodiac]

Put the engine on boat, assume has a prop ? if so, go for a wot spin with you alone with engine well trimmed and transom well height seated, check achieved max wot rpm, compare them to your engine's safety factory wot parameters.

Will know if currenty under or over propped, play with prop pitches to achieve the one that delivers near it's max wot rpm factory stated for that engine. Will need to install an induction tach if engine doesn't have one for wot test.

Happy Boating

[A1an]

That's the point, I've no prop at all and these props are hard to come by for some reason.

[RIB-Teccie]

Alan

These props are easy to come by, same as the 55yam. The standard prop supplied was 3 (blades) x 11.5. (Diameter) x 13 (pitch).

Try that to begin with. You can get them off eBay. The other type you can use is the plastic splined one from Barrus but they are harder to install as you need to combine the Yammy spacers and the Barrus ones.

[RIB-Teccie]

Specs, yam 50 & 60.

If it is a 50, it is the derated 55 with the twin gas assist rams. A genuine 60 Hp had the newer single ram. The gear ratio was different.

[A1an]

Thanks fella, it is a genuine 60, single ram under yoke instead of the twin outside rams.


Il look on eBay.

Cheers.

[bosun]

15''
at a guess !

[A1an]

Went for a 13", the nice lady in the dealer said return it if its the wrong one, I explained I could only tell it was the right prop AFTER using it, she was cool with that and said it wouldn't be a problem.

[bosun]

good news
Helpful dealer you have !

[A1an]

Originally Posted by bosun

good news
Helpful dealer you have !

AND they were £13 cheaper than I could find anywhere else.