Motor height

[dray63077]

How much will raising my motor really help? Right now the cavitation plate is about 2 inches below the bottom of the transom and the motor is mounted in the top hole.

[teecro]

Without knowing what size boat and motor, current prop size as well as speed and RPM we can't even give you a wild ass guess.... But generally boats that have their motors too low can hope to gain 2 to 4 miles per hour...

[dray63077]

Sorry. It is a 22foot fisher with 90hp merc. Wide open Roma are about 5600. I'm not sure of the prop pitch. Right now it will run about 19 mph with 2 people.

[Bamaman]

Getting them setup is all experience--trial and error. A dealer that sells a bunch of pontoon boats can usually make an estimate on where to set up the motor. I know the boat manufacturers often keep notes on propellers to use for which motors, and can tell you about what mph it should run.

My Bennie 24SSLX with the Yamaha 150 hp is set 3/4 inch above the transom, and I'm running a Reliance 15 pitch propeller. Trim it down, and I'm not getting any ventilation. I keep it trimmed up about 3/4 on the gauge all the time, and it vents slightly when I take off fast. At a cruise or faster, the nose of my boat sticks up and I can feel the wind pick up the front end. That's just like I like it.

[teecro]

Sorry. It is a 22foot fisher with 90hp merc. Wide open Roma are about 5600. I'm not sure of the prop pitch. Right now it will run about 19 mph with 2 people.

Age of the motor would help too as Merc as well as most other manf have changed their max RPM ratings over the years. But then again if it is a 4-stroke the max RPM "range" it is most likely 5,000 to 6,000 RPM so your not far off the mark at all. You should stand with a little more RPM. Before I'd go chasing different props I'd try raising the motor one or two holes and seeing what that may bring. It cost nothing as it can be done safely at home with a floor jack under the foot; it is plenty strong enough to support the motor while you move the bolts. Have you experimented with trimming the motor up a little while underway? Some folks are unaware that they can do this....

[teecro]

... I keep it trimmed up about 3/4 on the gauge all the time, and it vents slightly when I take off fast. At a cruise or faster, the nose of my boat sticks up and I can feel the wind pick up the front end. That's just like I like it.

Goes to show how different they all are... I've had two different motors on my 18-foot Party Barge and both of them (a 60 and 75) neither one of them want any more than 1/4 on the trim gauge... They both would gain RPM but lose speed...

[dray63077]

Sorry again. It is a 2000 model 2 stroke. I have tried trimming and it makes some difference. I am use to running a bass boat so pontoons are new to me.

[Bryden24shp]

Its anybody's guess where your best height will be. So many factors chime in. All you can do is play with it. Like T said, grab a floor jack and a 2x4, very carefully raise it by the skeg. Have a buddy help steady it. Super easy. Start out with the highest position, because its easier to lower it. REAL EASY! Hell, I've raised and lowered them on my small boats at the boat ramp, by sticking it back on the trailer and pulling it out to the parking lot. Uncouple the trailer and rest the skeg on top of a block of wood on the pavement and use the trailer jack to raise or lower the trailers tongue to adjust them. When in a pinch, you can get pretty creative! We added cup to a props with a hammer and receiver ball! The stupid shit we have thought of to get stuff done is crazy, but I guess that's what makes who we are... Die hard boaters!
(sorry, got off track... Working nights does that to you)
Make sure you test all of your changes under the same conditions and write down your findings. Then you can swap props, get divorced or adopt a kid and start all over again! Fun stuff, but the bottom line is..... HAVE FUN WITH IT!!!