posted 11-19-2006 03:51 PM ET (US)        

Thanks,

posted 11-19-2006 04:24 PM ET (US)            

I do not have this same problem nor do I have this same boat. I hope you don't mind me chiming in anyway.

Does the boat list while not moving? If it floats level but runs with a list then we can be reasonably sure it is not a weight distribution problem.

If there is a static lost, then that is certainly the problem or at least *part* of it.

How are the motors trimmed while underway?

Have you inspected the hull bottom for any obvious defect of problem?

Have you watched the trim tabs while underway to ascertain if they are functioning correctly and moving as you think they are?

posted 11-19-2006 08:00 PM ET (US)            

If your boat floats level side-to-side as you say it does, then your problem of listing while underway is NOT a weight distribution problem. You have some sort of dynamic problem.

The only thing of substantial weight that *might* shift side-to-side while running is the fuel in the fuel tank. But that would only happen if the fuel tank is mounted off center and had an odd shape, which it does not.

Yes, you could add or shift enough weight to make your boat level while underway but then it would list at the dock. That is not a solution, that is merely dealing with a symptom.

I would be looking at your trim tabs and your motors/propellers.

Things that typically can cause a boat to list while underway:

1) Improper weight distribution. But the simple test of this is to observe how a boat floats at the dock. If it floats level, weight distribution is not the problem.

2) Strong cross wind. A boat will always lean into the wind. But you would only have a list to port if you only ever ran your boat with a cross wind from port.

3) Propeller torque, especially when combined with a misadjusted trim tab on the motor. I would rule this out in this case because you have counter rotating twins and (I assume) you have the flat zincs with no fin to counteract steering torque. The counter rotating motor counteract each other.

4) Non-synchronized twin motors. If you have twin outboards and one motor is producing more thrust than the other then the boat will tend to yaw away form the side with the stronger motor. The maintain a straight course, the helm will have to be steered a little bit in the direction of the weaker motor and the sideways thrust vector of the motor will induce a list.

I have to presume you run the boat with the motors synchronized vis-à-vis RPM, no? This may sound silly, buy have you verified that you have the exact same model/pitch propellers on both motors?

posted 11-21-2006 11:46 AM ET (US)            

You would not perceive that you are steering in either direction in order to maintain a straight course. It is exactly like steering across a strong wind. You do not realize you are steering into the wind in order to maintain a straight course and counteract the weathervaning tendency, it just happens, as does the ensuing list.

If you are running the motors synchronized (and can rule out any problem with the instrumentation) then it could also be that the starboard motor is not developing as much power as the port motor.

Imagine the starboard motor is only running on three cylinders. (For the sake of argument let's say) it would only develop half as much power. You could still synchronize the motors but the port motor would be doing the most of the work. Ceteris paribus, the boat would consequently tend to steer to starboard. You, as the helmsman, would input steering to port to maintain a straight course. The motor thrust now being directed slightly to port as well as the rudder effect of the lower units would make the boat list to port.

That is one possible scenario. But consider anything on the hull itself that would tend to raise the starboard side (out of control trim tab?) or add drag to the starboard side (trim tab again). Transducers? Hull defect? Swim ladder dragging?

Another possible source of asymmetrical thrust would be motors mounted off center. I cannot believe this would happen and not be noticed. It would also not create much difference. It is amazing how off center a single motor can be before the effect is apparent. With twins, it would have to be a profound variance.

Have you checked the alignment of the two motors to one another. This is commonly referred to the toe-in or toe-out adjustment. Again, I doubt this is the case, but have it checked so you can rule it out.

posted 11-22-2006 08:50 AM ET (US)            

Have YOU calibrated the trim tab indicators as described in the bennett literature? Also make sure that they are doing what you think they are based on the indicator, and that they are even.

While you are trying to figure this out, it might make sense to get a clinometer - one with a fine scale - and temporarily mount it to the boat with double stick tape. This way you can check lean in a more objective manner, both at rest and running.

Also, whenever you measure lean, make sure a) you are running a straight compass course and b) you measure lean and then turn around and remeasure on a reciprocal course - this will take out any environmental factors like wind or current.

It really sucks when you have a new toy and something gets in the way of just having fun with it...