[abillmann]

Hey all,

I wanted to get your opinions on what's going on with my 19-foot Mariah 1900Z. It has a 4.3L Mercruiser Alpha One.

Last night was the first time I had the boat out with three other adults, and I couldn't get it up on plane. One guy was sitting in the bow, one guy in the center of the back bench seats, my girlfriend as co-pilot and me.

The boat would start to come out of the water, and then the engine would start to rev up slightly. The bow was fairly high. I had the prop trimmed all the way down.

I know this isn't a spun prop -- the prop is literally brand new (not rebuilt). And the reason I have a brand new prop is that I thought the previous one was spun because it exhibited the exact same symptoms. So two spun props, I think, is highly highly unlikely.

Both props are 14.5" x 19p -- a good all-purpose size for my boat. When I take the boat out alone, it pops right up on plane, so it certainly has something to do with the extra weight.

What might be going on?

[Z 202]

I was a bit worried about the title this thread, I thought it was about group sex...

It will take longer to get on plane with more weight on the boat, are you saying if you keep the thottle all the way down it never gets on plane?

It could be your trim limit sender is not set properly and the drive is not truly all the way down. In the fully lowered position the back end of anti-cavitation plate should be below level.

[abillmann]

That's correct -- with the throttle all the way down, it never gets on plane. It starts to come out of the water, then the engine RPMs increase at a fairly quick pace. It doesn't shoot up to redline or anything like that, but it's obvious that the engine RPMs are increasing, and the boat is no closer to planing out.

I'm wondering about the position of the trim as well. I'm not 100% convinced that the drive is all the way down when I think it is (and when the gauge says it is.) With my particular boat, a visual inspection is virtually impossible, as most of the outdrive is under the swim platform. And I would imagine a few degrees of tilt may be hard to see, but critical for getting up on plane.

I'm really really hoping it's not the engine coupler failing. Are there other symptoms of that?

[22empire]

If your boat is anything like mine you can adjust the trim all the way down, and you will hear a change in the trim motor tone when it hits the dead stop.. To my knowledge the indicator does not limit the trim it just report where the sender unit says it is... It is quiet so you could do it with the motor off. The tone should change. Open the engine hatch if you have too...

[mikeyt]

I agree with Z202.....at first i had some strange thoughts about the title.

After i thought about it for a bit then i figured, stop eating at McDonalds but i just knew that couldn't be it...

I agree that it could be a trim sensor/sender unit that needs some adjustment since that 19" prop should do the job. Also, what about a pair of Smart Tabs? The Smart tabs would definitely help you plane quicker and stay on plane longer....

[Z 202]

Yeah, I wouldn't rely on the gauge to tell you when the drive is trimmed all the way in. It's sender could be out of calibration as well (there are 2 senders on the drive, one is for the gauge, and one is for the trim limit).

Trim it all the way down in your slip and have a look under. You should still be able to ascertain if the drive appears to be fully in.

[abillmann]

I'm not relying on the gauge -- instead, as 22empire suggested, I'm relying on the change in tone of the trim motor when the unit is all the way down.

But even upon hearing that change in tone, is it possible that the drive STILL isn't all the way down?

[pimpadelic]

i have this same problem with my shabah except it does plane out it just takes longer with more people and more beer.

im running a 14 x 19 ss.

yesterday when i was out i had one person up front,me driving, wife next to me and a friend in the back. it was pretty rough water and i could not get it to plane out at wot. ???

will it take longer to plane out since i have a smaller engine?

[Z 202]

Originally Posted by abillmann

I'm not relying on the gauge -- instead, as 22empire suggested, I'm relying on the change in tone of the trim motor when the unit is all the way down.

But even upon hearing that change in tone, is it possible that the drive STILL isn't all the way down?

No, it should then be all the way down. Unless of course there is a mechanical obstruction. The trim limit sender only keeps the drive from being trimmed out too much, which pretty much invalidates my original assertion, that lack of in trim is due to a duff sender. Sorry about that, should've had another coffee before I posted that...

Originally Posted by pimpadelic

will it take longer to plane out since i have a smaller engine?

Yes. Heavy loads + less horsepower = longer time to plane.

[abillmann]

Here's what I'm doing with the drive trim:

(Push and hold "down" button)

[Sound from drive unit: RRRRRRRRRRRRRRRRRRRRRRRRReeeeeeeeeee]

^

That's the bottom, correct?


(Release "down" button).

There's basically no way it couldn't be ALL the way down.

Then, whether I hammer the throttle or slowly increase speed, the bow comes up a bit, and as the boat tries to get on plane, the engine RPMs start to increase, and it the speed slows a bit. It feels similar to an attempted takeoff with the drive tiltled up, but it isn't. And again, with a brand-new prop, there's no way it could be a spun hub.

So if it's NOT the trim of the drive, then what? (Please don't say engine coupler. Please don't say engine coupler.)