CHECK ZF GEAR RATIO

[hpeer]

I don't know what my gear ratio is Shop says prop is wrong for the boat. Suggest new prop but need info.

Prop was fitted by previous owner, I don't doubt it is not correct.

Yanmar 4JH4-TE
Hurth ZF-30

Hurth makes a 2.15F/2.64R and a 2.70F/2.64R version. Don't know what I have.

Called a dealer and they said to spin the transmission and count revolutions.

Any better ideas?

[TeddyDiver]

Look at the plate?

[Sailmonkey]

get a photo tach, and read input speed vs output speed........ probably cheaper to do what the dealer said though, just need to pull the trans off of the engine.

[hpeer]

Mech and I both looked at the plate and neither one of us could see an appropriate marking.

Maybe a quick trip to Harbor Freight is in order.

But then I need the boat in the water!

Would be nice if it had a decompression lever, which it does not.