i want to pull a tube or skier

[bolderdan]

I have a merc 650 outboard with distributor cd ignition. The full throttle rpm is 4800 - 5300. I want to pull a tube or skier but feel the boat doesn't have enough power. I think it may have to do with the prop. It is a 48-61814A1 11P. Do I need a larger pitch. Without a skier on a calm day, my boats top speed is 25ish mph. The boat is a 1975 15 ft sea sprite. Please help me figure this out?

 

[Bamaman1]

Re: i want to pull a tube or skier

I suggest you put a tuber or skier behind the boat, and see if it'll pull'em. Then, regroup.

I learned to ski in 1959 behind a Lonestar aluminum runabout with a 35 Johnson Sea Horse (gold color).

 

[bolderdan]

Re: i want to pull a tube or skier

I have. The boat only will due about 10-12 mph. Seems that other boats with the same motor size or even smaller pull much better.

 

[SparkieBoat]

Re: i want to pull a tube or skier

full throttle RPM should not fluctuate so much, you can usually get it to max RPM and hold it within 10 RPM. you need to post your GPS speed and exact max rpm with boat at wide open throttle and trimmed out with a light load, this will be your WOT RPMs. also post speed. then we can help you decide on a prop. but all in all you have a very slow set up and cannot expect much improvement, but should see some improvement with the correct prop. also make sure your motor is not too low, you could try raising it a couple of holes and see if it cavitates or not, my fin tab is out of the water at WOT and trimmed out.

 

[steelespike]

Re: i want to pull a tube or skier

Its bad form to have too posts on the same subject you should eliminate one or a mediator may combine them.Please read my reply in your other post.And reply here to avoid confusion;seeing there are more replys here.

 

[mayatan]

Re: i want to pull a tube or skier

I think there are some issues like previously stated like engine height or lots more. A decent running 65 hp merc on a mid 70's 15 foot boat should be at 32-36 mph all day long. I would have someone local look at your setup and figure it out. Could be engine or setup related but get your wot with just the driver up in the mid 30's at least then add the tube or skier. Good luck!