Troubleshooting Low Boat Performance: Rinker 18' with 4-Cyl Engine

Question
Hi, I have a 18' Rinker with a 4 cyl carb engine. I've been a little disappointed in the performance, and wonder if there are any mechanical problems. With only 1 person and low fuel the boat will top out at maybe 25 mph. With a couple people and pulling an adult on a tube or ski it struggles to plane out, though it usually eventually does. Is this all this boat is capable of or could there be a problem?

Answer
Hi Rusty...Thank you for selecting the undersigned to reply to your question.

I'm not a mechanic, however, there is one on AllExperts you can consult.

Although you didn't mention the yr. & make of I/O, have you considered getting a compression test done on the engine, and do you know the gear ratio in the out-drive? What shape are the sparks plugs & wiring in?

Often, slow or poor performance results from choice of propeller, and sometimes you have to experiment with pitch and diameter to achieve desired results.

I suggest you consult a local marina to help you make the right choice.

Safe Boating
Ron