1979 15' Chrysler Sport Satellite not sure if getting full speed

[Mm44012]

I got a 15' with a 45hp Chrysler motor. At WOT I get almost 20mph with just the wife and I on there. Anymore than that and I am only getting like 10 to 12 mph. Any help would be great.

Experience Level: Former MK. U.S. Coast Guard

 

[southkogs]

Welcome aboard. New to you boat, or did this one go just fine in the past?

I've seen 15' boats only rated for 50HP, but I've also had one that was rated for 100HP and a 50 would just barely get it on top of the water with a light load.

What kind of RPMs are you getting at WOT?

 

[Maclin]

You may be slightly underpowered, and over-propped.

I had a 1972 model of that boat, Sport Satellite 15.5 footer trihull, had a 55hp Chrysler. I think the boat was rated for 75hp. With an 11p prop it could do 29.9 (standing joke in my family) with 3-4 people. When I had a 12p prop on it if it was more than just me I had problems getting on plane. With the 11p and just me and 1 passenger it could get to top speed in 8 seconds.

 

[Mm44012]

I just got the boat. I got the whole set up for $100. I talked to the previous owner and he said most he would get is like 17mph. Not sure on the RPM, I believe the gauge is bad. I thought it might be over propped. Was thinking of getting an 11 pitch. What is the prop width supposed to be? Should I try trimming the engine in or out? Just seems really slow.

 

[Mm44012]

The boat came with what I believe is a 12.5 pitch prop.

 

[Maclin]

I will respond in your thread in the Props section