I'm sure this question has been asked but i couldn't find anything relevant in my results even with a variety of search terms. I recently acquired my '98 42' Fountain Lightning equipped with triple 525 SC's. Here is my question. When the boat is up and running at any speed the center motor is consistently turning 400-500 less RPM than the Port and Stbd. motors with the throttles even. I can bring the center RPM up to match the other two but then the center engine's throttle is 1/2 to 3/4" higher than the other two. I have verified that the throttles are all in sync with the opening of the carburetors and switched the center and the starboard prop to make sure that it's not a damaged prop.

Is this typical with a boat with triples, or do I have an engine down on power?

I would think since the prop is deeper int he water, it has more load on it bogging the RPM.

put a blower on the center one only... hahaha

Already has one. ;-) One thing that I did notice is that cruising around 3000 RPM on the other two motors they are not making any boost, but the center motor that is only running ~2600 RPM is making 2# of boost. So this should represent high load/low RPM.

My guess as well. Center drive deeper putting more load on the motor.

Anyone else on this??

I believe back in the day, it was very common to see the center engine with a smaller pitch prop. For example, if you were running 28p on the outer drives, the center one would have a 26p. Or, ive seen where the center prop was "Labbed" to get the rpm in synch.

Makes sense.

Alright, thanks guys. I guess that would also be why Merc and a few other manufactures now have a "Sync" option with their electronically controlled throttle systems.

Was going to suggest you chat with one of the supporting prop vendors. I'm sure they have run across this before. 400-500 r.p.m. sounds like somewhere between 1-2" of pitch. $375 + shipping to have your center prop labbed...you're getting off easy! Bet you need Tower clearance before you nail the throttles... over 90?

I had the same issue on mine. I raised the center with a shorty and it made the center more equal. It still appears to need more juice to perform the same but not as much.

A friend of mine has a 47 Fountain and his has a three blade center prop instead of four blades on the port and starboard motors which seems to make it perform more equally.