Propeller Pitch

Rich K · Apr 27, 2018

I am currently looking for my next boat here in the PNW, something between 34’ and 42’. One that caught my eye had something odd to me, that I need to ask about.

It has twin Lehman 120s but one prop is a 24LH17, and the other is a24RH18. I can’t imagine why they would have a different pitch. Wouldn’t be hard to sync the two engines if they are pitched different? Would there be any other results that might manifest themselves with such an arrangement?

Would appreciate any information or experience any of you have with such a thing, as I have searched on the web, and cannot find any information that would tell me if this was okay or not.
Thanks.
RichK

kchace · Apr 27, 2018

Check the transmissions. Perhaps they are slightly different ratios?

Baker · Apr 27, 2018

kchace said:
Check the transmissions. Perhaps they are slightly different ratios?

That is a very good answer!

Nomad Willy · Apr 27, 2018

See if the blades have a slightly different shape and thus a different blade area. Then you either cut the other blade to match or match load w a pitch change.
If it’s not obvious measure balde width ect. One or both blades could have been modified. Another posibility is that pitch was taken out of one to balance the load and not marked on the hub or the prop man forgot to mark it.

The only real way yo tell the pitch is to have a prop man check it on the prop dies.

timb · Apr 27, 2018

I have heard of the counter rotating trans going out because of the makers running the trans in reverse. then later people put in one twin disk trans .maybe the ratios are a little off.

Keysdisease · Apr 27, 2018

Just because that's what's stamped on the hub doesn't mean that's what you've got.

:socool:

Comodave · Apr 27, 2018

+1 on the transmission ratios being different.

JohnS · Apr 27, 2018

Pitch difference

I have a similar condition on La Vita Dolce, a 1986 Cheoy Lee 40 with Lehman 135s. Apparently there wasn't a 2 to 1 left hand trans available when she was built, so the diffrrence was made up on the prop. My Port engine has a 1.91 to 1 ratio.
PO had contacted the factory about yhis when he bought the boat, and their response letter is still with her papers.
It does, however make the synchronizer off a bit, as mine reads off the shafts.
JohnS

Propeller Pitch

Rich K

Member

kchace

Guru

Baker

TF Site Team/Forum Founder

Nomad Willy

Guru

timb

Guru

Keysdisease

Guru

Comodave

Moderator Emeritus

JohnS

Senior Member

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