wont plane/lack of power

[faurot3]

I have a 1986 21' sylvan offshore. it has a 2.5L 4cyl omc. it will plane out if i have just myself and a friend in the boat on an inland lake, but when i take it out on a great lake with 4 guys and all the gear it just doesnt want to plane out and go. Even on the calm lakes when i plane out it only goes about 23mph and i think i should go faster. I revs to WOT no problem when its not in the water. The prop is a 13.25X17. The owner befor me used it for tubing and pleasur boating so im thinking he didnt have this problem. Any ideas would help. Would plugs cap rotor wires help? im an electrician not a mechanic so any ideas would help im stumped?

 

[CV16]

Re: wont plane/lack of power

It sounds to me like you need a different prop when you go out with a boat load. Also, I was always told to never rev the motor while on muffs. What are the rpm's when you are with just your friend?

 

[faurot3]

Re: wont plane/lack of power

It would only rev to 3000 on lake Erie this weekend. I don't know what it revved to with only one other person. Maybe I'll take it out on the water tonight. I only put the muffs on to make sure it would go over 3000 with no load.

 

[airdvr1227]

Re: wont plane/lack of power

First thing that jumped out at me was a 4cyl isn't a very big powerplant for a 21' boat. Lack of HP would mean you need a lower pitch prop. You're going to need to know what the WOT is currently and what is recommended for that boat/motor combo. Gotta be more than 3000 rpms though.

 

[Howard Sterndrive]

Re: wont plane/lack of power

that little engine in a big boat is going to have to be well tuned all the time... you need every pony

you need to start with cleaning the flame arrester, changing the fuel filter, and tuning her up (points, cap , rotor, plugs) . Check compression -you are removing plugs anyways.

Don't change any props until you are sure it's making full power.

a good checklist here:
http://forums.iboats.com/showthread.php?t=295070

 

[faurot3]

Re: wont plane/lack of power

i think a tune up is probably in order. i wonder why they would put that small motor in. i was thinking cap rotor plugs would b a good start. im going to run over to a nearby lake tonight and see what wot is with just me and the kids.