[qctaipan]

This question will expose me for the rookie I am however I do have a dumb question. I have a 91 2150 XLC and can't seem to trim to an easy plane. Have tried a couple different props and only way to achieve a plane is to put a person in the cabin for weight until plane is achieved. Boat holds plane once there until I slow way down, then process has to be repeated. Can yoi help?

[mikeyt]

Give some consideration to installing a set of Smart Tabs. Do a search for 'Smart Tabs' on this site and you will find all kinds of information.

[qctaipan]

Thank you for the suggestion. I already tried installing a fin on lower unit which didn't help much, I will try the Smart Tabs next.

[midwest mariah]

I would think a 5.7 would get you on plane quickly. Your outdrive is in the lowest position? have you verified by actually looking at the unit to know for sure that it is in the lowest position?

[blockp]

What size and pitch prop do you have on it? How many people in the boat and how much fuel when it doesn't plane out? Once you plane out, what's your top speed and WOT rpm?

[mikeyt]

As 'blockp' suggests, the prop pitch you are using is a good possibility assuming that the props you were using were in good repair. I would suggest that with your boat being a cuddy & the 5.7L, a 19" pitch prop would be a good place to start. Anything higher than that and you would have trouble getting on to plane & keeping it there at low speed. The hydrofoil / fin is a waste of money.....even though it is cheap.

I agree with 'midwest' too. You want to visibly check to see if your outdrive is actually trimming all the way in and out & not just by what the gauge says.

[qctaipan]

Yes lower unit does fully engage and does have trim tabs. Not sure if I have correct pitch on prop, ruined it over the weekend so will have my marina match correct to motor and boat to see if that helps, if not will try smart-tabs next. Thanks for reply.

[qctaipan]

I'm not sure size & pitch of prop however ruined it over weekend and wil have marina match proper size & pitch to motor and boat to see if plane time improves. I usualy have 4 people on boat with full tank to start and half by end of day. Speedo shows about 32 mph w/4000+ RPM.

[qctaipan]

thanks

[blockp]

Originally Posted by qctaipan

Yes lower unit does fully engage and does have trim tabs. Not sure if I have correct pitch on prop, ruined it over the weekend so will have my marina match correct to motor and boat to see if that helps, if not will try smart-tabs next. Thanks for reply.

What do you mean "does have trim tabs"?

If you're only turning 4000 rpm at WOT, you're over propped. You should be able to turn 4800 rpm at WOT. 2 degrees in pitch for every 400 rpm, so you're about 4 degrees too high on your current prop. Meaning, you might be running a 25p when you should have a 21p. Before you spend any money on the new prop, find out what the current pitch and size is, then ask the marina what they're replacing it with. I don't think I'd spend a dime replacing it with the same size and pitch as the one that obviously isn't the correct one.