Mercruiser Outdrive Hydrofoil - Pros and Cons

[Scorpion8]

Okay, now that I am at home.....

 

[HT32BSX115]

Okay, now that I am at home.....

And, What is your observed WOT RPM when trimmed for maximum speed?

It would also help if you post your Mercruiser recommended WOT RPM range for your model engine (found in your Mercruiser owners manual)

Should be something like 4400-4800 or 4600-5000 RPM etc.........

 

[500dollar744ti]

My DoelFin has been on my Mercruiser outdrive for 31 years now. My son has had one on his Mercruiser for 7 years now. His also has a 4 blade prop. We both would not be without them. Not a single negative, all positives.

They rob you of some top speed but if you aren't concerned with that, I can see no other negatives.

 

[JimS123]

They rob you of some top speed but if you aren't concerned with that, I can see no other negatives.

At WOT lost only about 1 mph. But, cruising speed increased, and fuel consumption decreased at cruise.

THAT, t me as a win-win for only 39 bucks investment. So, the loss posed no practical disadvantage. I see no need to ever run at WOT, and burn all that fuel needlessly.

 

[HT32BSX115]

He hasn't posted his WOT RPM and speed though..........

It would be nice to know that the engine is making rated power and propped correctly before adding additional drag devices

 

[JimS123]

I have a custom pitched double cupped SS prop. It was originally a 21", but I had it re-pitched to 19 in order to increase the rpms. So, its not really a 19, but somewhere in between because obviously only the tips could be re-pitched.

WOT rpm = 4600 and speed is 46 mph. That is with a digital paddle wheel speedometer because GPS wasn't invented back then. Today's GPS readings agree with that old speedometer.