Driving me 'round the bend

[Quattro]

I've spent the last three days researching this problem and am puzzled by the latest recommendation I received. Here goes -

I'm running a 1999/2000 Mercury 90ELPTO 2-stoke on a 5.2M Haines Signature (fibreglass).

It pulls dangerously to the right. If were to let go at speed, I would loose passengers!

Every post I have seen says the trim tab set to the right. Now my interpretation of 'right' is looking at the back of the boat, loosen the bolt so that the tab points over my right shoulder.

The problem is that it is already maxed out to the right. A service manager today said I should swing it to the left.

I mentioned to him that I thought the engine was mounted one bolt whole too high so the trim tab was doing little. He said that if that was the case, I would have many other problems before torque steer.

Are you able to offer some advice?

 

[tashasdaddy]

Re: Driving me 'round the bend

your AV plate should be 1-2 inches above the keel. pulling to the right, looking from behind the boat, move the back of the trim fin, to the right. if you get maxed out, you may have to go to nofeedback steering helm, or hydrolic steering, but this just masks the problem.

 

[Quattro]

Re: Driving me 'round the bend

Here are some pics.

The anti-vent plate is almost exactly two inches above the hull bottom.
The trim tab is fully around. Is it in the wrong direction?

 

[Rosati]

Re: Driving me 'round the bend

Adjust it back to center and start from there. It should be easily ajusted on the water. Start at half throttle to insure no adverse reactions.

 

[jimg984]

Re: Driving me 'round the bend

wrong direction

 

[CharlieB]

Re: Driving me 'round the bend

How 'loose' is the swivel bracket bushings?

Can you 'lift' or 'shake' the motor and see or feel play in the pivot bushings?



There is also larger trim tab made for special applications.

 

[Quattro]

Re: Driving me 'round the bend

I have now tried the trim tab in all directions with no success. It still pulls dangerously hard to the right. The only way I get some relief from it is to trim it as high as it will go without the prop starting to come out the water.

 

[Dunaruna]

Re: Driving me 'round the bend

It is NOT in the wrong direction for a right (starboard) pull. The trailing edge of the tab should point towards the pull. Your tab is set correctly.

That being said, you obviously have a serious issue that is not related to the tab adjustment. If it was my boat, I would firstly double check that the motor is mounted dead centre on the transom, then I would carefully check for any hooks (including the skeg). Then I would start playing around with different props.

Just out of interest, your rig look decidedly Australian, where are you?

 

[Yachtzee]

Re: Driving me 'round the bend

I am not one of the old time experts here but I would say that with the trim tab in that position you are going to make tight right hand circles.
It works like a little rudder on the back of the boat. In the position shown it is going to drive the stern to port pushing the bow to starboard = Right hand circles. Try the turnig it the other way

 

[HONKER1]

Re: Driving me 'round the bend

I am just going to throw this out there, because I don't hold a light to these IBOAT experts. I may be way off base, but which way is you propeller shaft turning. Just a thought?

 

[Dunaruna]

Re: Driving me 'round the bend

I am not one of the old time experts here but I would say that with the trim tab in that position you are going to make tight right hand circles.
It works like a little rudder on the back of the boat. In the position shown it is going to drive the stern to port pushing the bow to starboard = Right hand circles. Try the turnig it the other way

The trim tab rudder steers the motor, not the boat.

The torque from the propeller will steer most boats to starboard. In other words, it is harder to turn to port. When the tab is adjusted to starboard it counteracts the torque of the propeller thus making it easier to turn to port. You now have two opposing forces which hopefully equal zero.

 

[Quattro]

Re: Driving me 'round the bend

Thank you all for your assistance.

With the boat on the driveway, I did a bit of thinking and think I may have found something.

If I grab the outboard and push it, it will fall easily to the right (making the boat turn right). If I push it the left, there is some resistance.

Now I have a very basic steering setup, so something must out of balance to cause this.

I've attached a couple of photos of my steering setup. The rod will come out very easily out of the housing, but goes back in with some reluctance.

 

[Quattro]

Re: Driving me 'round the bend

OK, took the boat and my theories to a recommended Merc mechanic. He fitted a Teleflex No Feedback helm and the steering is behaving. I can take my hands off the steering and it won't move. There is no perceivable difference in turning port or starboard.