Cavitation

[cuttlefish]

I have a 50 hp Honda with an aluminum prop (11.25 pitch). Between about 1500 and 2500 engine rpm there is a loud, high pitched whine. I think it is from prop cavitation. Anyone know of a cure for this short of buying another prop?

 

[scott craven]

I have same motor, never had that problem yet
Is the motor trimmed down ? does this happen upon acceleration ?
seems like low rpms for cavitation.

 

[Island Fish Lifter]

quote:Originally posted by cuttlefish

I have a 50 hp Honda with an aluminum prop (11.25 pitch). Between about 1500 and 2500 engine rpm there is a loud, high pitched whine. I think it is from prop cavitation. Anyone know of a cure for this short of buying another prop?

Thats a bit of a vague description, Does the rpms rise when this happens? How long has it done this? has it gotten progressively worse?
The first thing to check is your prop hub. When its out of the water, use punch marks or paint marker on the prop/ shaft. The next time you use it the marks should stay in the same position in relation to each other... If not, your hubs slipping.

Fill the dam tub!

 

[cuttlefish]

Thanks guys,
Sorry about the vague description. It only happens at low rpm which unfortunately is in my trolling speed range. It has made the whine since I've had the prop, two years. Doesn't seem to be getting any worse. No rise in rpm when it happens. I will mark and check the hub.

 

[beemer]

sounds like it is ventilating not cavitating.

 

[Island Fish Lifter]

I dont think its doing either. If it was a prop hub slipping, or ventilating, it would happen under load only. Sounds like you have something else going on under that hood. Good luck, where are you located?

Fill the dam tub!

 

[Barnacle Bill]

Between 1500 - 2500 RPM, wouldn't the motor be under load at that range? Not planning for sure and not trolling at that rpm. Prop slipping or trouble in the engine like IFL says?,..........BB

 

[cuttlefish]

Thanks guys.
Engine starts fine and runs smooth at all rpm, from low idle to full tilt. I guess I'll have to try another prop. In Port Hardy BTW.

 

[Charlie]

I don't know, but you have an aluminum prop... if it is cavitation, it will show on the prop! The black paint will be gone and you will see pits starting to form on the blades?