Boat listing

[De Wa]

Trying to help a friend. Was on a friends boat which is a 17 ft mono hull fitted with twin Yamaha 60 hp two strokers

When in the water she appears to float level. Its a total different story when on the plain at about half to three quarter throttle.

The boat tends to list to the left, runs deeper in the water than on the right side and becomes scary at times, unsafe in my opinion.

We have checked that both motor`s are installed at the same height,the trim is set the same.

Any suggestions on what could be causing this problem.The motor`s have allie Yamaha semi cleavers fitted

Rgdz
De Wa

 

[Skeltonsc]

Good day,

This is why most if not all bigger boats and motor combinations use counter rotation on the outboards.

I'm going to have exactly the same issue on my new Duck with twin 60HP outboards

The Props are turning clockwise and pushing the boat anti clockwise.

Trim motor height steering fins are not going to make any difference.

Maybe the whale fins or trim tabs.

Here's some info on the problem

http://continuouswave.com/ubb/Forum4/HTML/007691.html


[font="Verdana, Arial"]Will a different propeller correct bad torque action (listing and hard steering)?Not usually. Most likely it is the result of any of several irregularities in the hull, the steering hook-up or the engine mounting. Steering wheel must be properly located relative to propeller rotation. If an engine has a right hand rotating propeller, steering wheel should be on the right or starboard side. This side normally would tend to lift as the result of torque action and the driver’s weight offsets it. Modern outboards have built-in features in the lower units to compensate for torque. Engine tilt should be such that the prop is horizontal when underway. If it is up or down, the propeller can have a definite pull to one side. See that the engine is at the exact center of the transom and is setting level. Steering linkage should have enough adequate sized pulleys, properly swiveled and with the right cable tension. Check boat bottom for warping, distortion, which could cause difficulty.
[/font]

 

[Limpopoking]

From what I know, counter rotating motors only really start becoming a factor after about 150Hp, and even then, only marginally till you get above 200 horses.

Your mate's problem sounds like a hull issue. My little C-Ski did that and I'd skipper from the high side of the helm (Starbd in my case). If I had crew, I'd use them to compensate.

 

[MichaelK]

Check this thread out, hope it helps
http://www.sealine.co.za/view_topic.php?id=103908&forum_id=19&page=2

Eventually turned out to be sticky throttle cables with this chaps boat.

 

[De Wa]

Thanks for the information and advice We now have to systematically work through the suggestions

 

[Fishpaste]

De Wa wrote:

Thanks for the information and advice We now have to systematically work through the suggestions

.

 

[QuQ]

Its not going to be as a result of non-counter rotational motors on a rig that size. Definitely a hull design / weight balance issue. Also, both motors don't need to be trimmed to the same level when underway (especially noticeable on cats where raising the starboard motor, causes the port-side bow to lift, and visa versa). Experiment a bit.