Minx handling problems....

[gcarter]

last weekend in Kentucky. Five times the Minx would roll over on the left side. Three of the times while getting on plane. Twice while going straight while on plane. Once while going about 30 MPH, and the worst, while going about 50 MPH. It was as though the hand of God reached down and rolled the boat over on the left side. It stayed there till I chopped the power. It was very scary. Elaines elbow was in the water, remember the Minx has an extraordinary amout of freeboard for a Donzi. The other girl in the back seat fell on top of Elaine and both girls almost went into the water. The person running behind us said it looked very strange.
So here are the particulars;
I wasn't using any tabs.
The tabs work perfectly.
The boat has 14 hours on it since the restorartion.
The U-Joints had just started making some noise at full lock, but no other time.
I've asked Poodle and Trueser for their opinions;
Gimbal bearing
Engine alignment
Steering cable
cable joint on steering cable
So this is what I've found so far;
Gimbal bearing is excellant, smooth and plenty of grease.
Alignment is certainly acceptable, it may be down one thread at the front mounts. But I have no problem getting the alignment tool in.
Some of the front mount bolts were loose, one on port side, maybe both on stbd side ( I haven't gotten there yet). I'm replacing the 3/8" bolts with 7/16" bolts w/ jam nuts instead of Ny-locks that have already loosened in the past.
Checked steering slop, maybe 1/4" at the rear of the cavitation plate.
Checked rotational play in the drive around the input shaft axis (movement in the gimbal ring) none.
I'm replacing U-joints this weekend.
Rear mount bolts are tight, but I haven't checked torque yet.
Guys, I need some serious help here. I've not experienced anything like this before. Elaine says she won't ride again till I find something wrong and fix it.
It was a very disconcerting experience.
Any ideas?

[Cuda]

Did the boat tend to track straight when it happened, or did it try to go into a turn?

[BUIZILLA]

A short in the trim tab switch...

[Cuda]

Jim might be on to something there. Yesterday was the first time I ever used the tabs on my Minx, and I can tell you it's VERY sensetive to tabs. Skeered me a little yesterday.

[gcarter]

A short in the trim tab switch...

Jim, I've thought about that, a lot. My question is, if that were the problem, then when I physically checked the tab position, wouldn't the offending tab still be down?

[gcarter]

Did the boat tend to track straight when it happened, or did it try to go into a turn?

No, straight. Except, of course for torque steer (I don't have a trim tab behind the prop).
I guess I would have to say I don't think so. But I'm always steering to the right a little.

[Ranman]

If the issue is as pronounced as you are describing, I bet it has something to do with the tabs. Can you tie them up, remove, or otherwise limit downward travel to test?

This may be silly, but is the hull bottom straight and true? Do you have an obscene amount of weight on one side?

[gcarter]

Randy, I must admit, it acts EXACTLY like a tab down. It would be easy enough to pull the tab fuse. The bottom is kind of like every other Donzi bottom, a little hook on both sides, but pretty symetrical.
But it NEVER did it before.
I'm going to finish this work I've already started, and dis-able the tabs. If it never happens again, I'll know I've found the problem.
It just irks my engineering background if I can't find something wrong that's repeatable. And Elaine will always be fearful if I can't definatively determine the source of the problem.
You know, it takes three wires (power, port or stbd, forward or reverse) to be connected to start a particular action in the tabs. It takes a different combination of three wires to retract the same tab. What are the odds?
Hopefully I figure it out.

[txtaz]

George, If it tracks straight when it happens, it must be the tabs. There is nothing else that would throw the attitude off like that. Are all screw tight? Loose pins? Play in the hydraulics or air? resevoir full?
Get it fixed, Elaine wants a ride....LOL
Wes

[gcarter]

Get it fixed, Elaine wants a ride....LOL
Wes

I'm not sure she does right now.

[BUIZILLA]

George, take the rocker switch out, open it up, and you'll see why I said that... i've had it happen to me before. The rocker contactors may come loose from the back of the rocker itself internally, and they WILL cross over two terminals, setting one or both tabs in motion. The rocker can also come off it's pivot pin if the housing has been damaged at some point or previously opened up, and not closed back up properly. Very rare, but it can happen... The Minx is actually top heavy with the high freeboard sides, and narrow beam, so it doesn't take much to make it roll over on it's rail... I can take my old Minx, and roll water right up to, or over, the windshield frame very easily, if I wanted to. If it happens as fast as you say it is, then BOTH tabs are moving at the same time, one up and one down... which strengthen's my cross-contact theory even more...

JH

[mattyboy]

George ,
that happened to me a few times when i had the tabs down unevenly to adjust for my fat ass when i landed or it a wake on the side of the tab deflected the the most it would catch and like a big tiller shift the boat that way

[gcarter]

George, take the rocker switch out, open it up, and you'll see why I said that... i've had it happen to me before. The rocker contactors may come loose from the back of the rocker itself internally, and they WILL cross over two terminals, setting one or both tabs in motion. The rocker can also come off it's pivot pin if the housing has been damaged at some point or previously opened up, and not closed back up properly. Very rare, but it can happen... The Minx is actually top heavy with the high freeboard sides, and narrow beam, so it doesn't take much to make it roll over on it's rail... I can take my old Minx, and roll water right up to, or over, the windshield frame very easily, if I wanted to. If it happens as fast as you say it is, then BOTH tabs are moving at the same time, one up and one down... which strengthen's my cross-contact theory even more...

JH

Jim, I sure do see what your getting at. The fact that these are brand new Carling water proof switches probably don't make any difference.
Two switches, one port, one stbd.
On the plus side, it would be easy to change switches.

[BUIZILLA]

Trace your red/ green wires from the pump to the solenoid(s)..... one leg of that solenoid can energize if it's bad... the old style merc solenoid's could do that, but i've never heard of a new style small body solenoid doing it, if you have those. The switch I was referencing was the old style black Bennett combo rocker that is NOT sealed from the elements. Make sure your Carlings have a distinct, and very positive, neutral detent position.

JH

[gcarter]

Jim, I think it would be worthwhile to change the stbd switch. They're not that expensive.