I have a 22' Pontoon Boat and a 90 HP Mercury four stroke engine that runs like a charm. But, the boat unloaded only attains a top speed of 18MPH at 6000 RPM. I've tried changing the engine trim settings but 18 MPH is absolutely tops.

The engine has a prop with a pitch of 13".

"Question: does this boat need a prop with more pitch, perhaps 15" or 17", to let it top out at, perhaps, 25 MPH.

My last pontoon boat, same size, with a 90 HP two stroke Yamaha engine would run 25 MPH at 5500 RPM.

Is there a reputable prop shop close to Tyler.

Any help appreciated.

^ that is the answer.

Thanks for the info, guys. But, I still have the problem. I just conversed with Steve, and I acknowledge he is the best resident prop guru around, with gobs of very satisfied customers, but he tells me this engine, the 90HP Mercury 4St, is doing all it will do, and doing it efficiently. I accept he is right.

But, in the past fifteen years I have owned five pontoons, all 20-22 foot models and have had 50 2St, 75 2 St., 75 4 St., 90 2 St, and this 90 4 St engines on them. They all would do the 18 MPH this one will do, and a couple would surpass it going up to 25 MPH. That would make this 90HP 4 St Mercury the weakest engine of the bunch. I am having trouble convincing myself that this is the case. Surely this engine will do more than a Old 50Hp Evinrude 2 St engine. But it is not.

I'm 78 years of age and have owned and operated and maintained boats continuously since 1954. And, I am having trouble getting my arms around the fact that our new and wonderful boats with 4 Stroke, EFI, great engineering in so many ways are just not up to doing what our old standard 2 stroke, carbureted engines would do.

I accept Steve is correct and I am the acknowledged amateur, so I still have some tinkering to do on this. Back to the drawing board.

I think if you are getting 6000 RPM with that prop,you could afford to sacrifice a few rpms and gain a little more top speed with a 15pitch prop,but at the cost of losing a bit of "hole-shot" acceleration...I would get a cheap aluminum prop from iBoats.com and try it.

Another thought...Does this boat live in a marina? The other boats before this live in a marina? Just wondered,cause that crust formed on my boat cost me a few mph.

Thanks Jed. I think that's what I'm going to need to do. No one seems to be an expert in pontoon props.

The boat is kept in a boat slip in a private boat house and is always elevated in a lift. The toons are spotless. I fish on the lower end of the lake, and need it to do at least 23-25 MPH. At 18 MPH it is a 30 minute run to fish.

You might post your question on one of the ponton forum, but what you are currently getting (18-20 mph) sounds typical.

Woody, just curious. What is the top speed on your 18' Tracker pontoon. It is almost identical to mine although two feet shorter.

Were all those other speeds from the other boats GPS or water pressure type guage speed? Only trust GPS speed

I get around 18 mph at top speed, although I rarely push it that hard.