Severe Torque Steer To Port

[1960 Starflite]

1979 Century, 19 Ft, 140 HP Mercuriser I/O

I did a search on this fourm for an answer, found a couple old threads, but they never finished the discussion. Would be nice if people reported how/if they solved their problems.

As long as I leave the trim completely down the boat will steer without a problem. As I start to raise the trim, after the boat planes, I get severe torque steer to port. It is so bad that I must keep both hands on the wheel or it will turn a quick circle to the left. I really can't say just when this started, but it use to go straight when it was trimmed up.

I've moved the trim tab (trailering edge to port) as far as it will go. I even ground additional clearence on the tab stop (upper side) to move it even futher.

I changed from a 3 blade, 14 1/2" x 19 pitch prop to a 4 blade 14 1/2" x 17 pitch prop thinking it would help, It didn't. The engine operates at 4400 rpm with both props, right where it should be.

The drive has a whale tail on it, been there for years. The skag isn't broken or bent. I don't see any visible problem with the hull. I just put the boat in the lake, where it stays all summer, in the boathouse. It is always stored in my garage for the winter months.

I need help, please !!

Tom

 

[Charlie in TX]

Re: Severe Torque Steer To Port

Is the outdrive turning? Have someone look out the back of the boat at the outdrive, trim the outdrive up, have them look for changes in the water leaving the hull or for the outdrive to crank over.

 

[Don S]

Re: Severe Torque Steer To Port

 

[Texasmark]

Re: Severe Torque Steer To Port

Don sir, he said he already tabbed over to the side it favored as far as it would go plus did a little filing.


Thinking about what he said and it doesn't make sense. Something obviously changed......Say Starflite, why don't you take your tail off just to get a data point. Thinking about what could have changed and what you said you checked, there might be something there....some damage causing it.

Also, how is your load distributed? How level does your boat sit at rest port-starboard?

If all that doesn't help, what about a hook in the hull?

HTH,
Mark

 

[1960 Starflite]

Re: Severe Torque Steer To Port

Mark, Thanks for feedback. I looked at the paint line on the transom and the boat is sitting level at rest. The boat never has any water inside and since it was in the garage all winter there isn't any moisture in it either. As far as the load, fuel tank (30 gal) is centered under the bow, battery is located port side, rear and the trim pump is starboard side, so I would think these would offset each other. I'm going to pull the whale tail off in the next few days and see what happens.

The lake was smooth yesterday (no passenger) and I noticed that when I trimmed up just a few degrees it pulled to starboard, but not much torque at all. Then as I trimmed up a little more all of a sudden it pulled HARD to port. I can't believe that little four banger engine could produce such a force. If I leave the trim all the way down I can pretty much let go of the wheel and it will run straight at WOT.

I have to ask, What is a HOOK in the hull?

Tom

 

[DuckHunterJon]

Re: Severe Torque Steer To Port

Just a guess, is there any damage to the skeg?

 

[Aquaman-PSD]

Re: Severe Torque Steer To Port

A hook in the hull is a indetion in the hull ussually from sitting on a trailer too long. But if you said it is wet docked through the summer this sounds unlikely.

 

[Grandad]

Re: Severe Torque Steer To Port

The lake was smooth yesterday (no passenger) and I noticed that when I trimmed up just a few degrees it pulled to starboard, but not much torque at all. Then as I trimmed up a little more all of a sudden it pulled HARD to port. I can't believe that little four banger engine could produce such a force. If I leave the trim all the way down I can pretty much let go of the wheel and it will run straight at WOT.Tom

Tom - I'd look for the obvious first. If sometimes the pull is to starboard and then to port, I'd suspect excess play in your steering linkage such that the outdrive is able to slop back and forth.
Is there a loose or broken link?
Back at the dock or on the trailer, can you manually turn the outdrive by pushing on it when trimmed both up and down without steering wheel movement?
Is the Mercruiser trim tab loose such that it can turn while underway?
Is your gimble ring cracked?
This sounds more severe than just an improper adjustment. - Grandad

 

[Texasmark]

Re: Severe Torque Steer To Port

Agreeing with pops about more serious. As you are triming out you are obviously changing the ability of the tab to function and the higher you trim the less it's effect. Additionally, unless it is submerged at the time, the more you trim out the less of the tab is in the water hence any error from it would decrease with increased up trim. Tabs do have their sweet spot and are normally adjusted for minimum helm interference at the trim/speed you use the most. The sudden change and magnitude of it makes me agree with pops that something is loose and once the load gets to a certain point it moves out of position and you have your problem.

Good luck,

Mark

 

[project1]

Re: Severe Torque Steer To Port

check your prop to pad height.. If youre too high it will cause a sever torque steer problem. I am working the bugs out of a boat I just bought and that was one of them. I lowered the motor and all torque steer went away but now I am fighting a chine walking problem. It a matter of finding the right setup for your boat.. good luck.

 

[haulnazz15]

Re: Severe Torque Steer To Port

check your prop to pad height.. If youre too high it will cause a sever torque steer problem. I am working the bugs out of a boat I just bought and that was one of them. I lowered the motor and all torque steer went away but now I am fighting a chine walking problem. It a matter of finding the right setup for your boat.. good luck.

I'm not sure that applies to an I/O. It's pretty difficult to adjust the motor height once the hole in the transom has been cut, lol.

 

[project1]

Re: Severe Torque Steer To Port

I guess it would have helped if I had read all the posts first....lol

 

[Outsider]

Re: Severe Torque Steer To Port

OK, I'm missing something with all this talk about props and motor holes. The OP said the tab is all the way to port, plus some driveway modification. If the image below is accurate, no freakin wonder he has to use two hands to port! Relieving pressure to port (steers easily to starboard) requires moving the tab to starboard. The steering initially pulls left because of prop torgue before the tab is effective.

OP, take off the hydro-foil, those things can mask far more problems than they solve. Then center the tab and go run it. There may very well be a difference in steering effort from trimmed down to trimmed up. When I had the problem, I adjusted the tab for minimum force (ideally 'none') when at speed with the engine trimmed out. Basically, if you have to hold pressure to port, move the tab to starboard, not further to port ... :facepalm:

 

[81 Checkmate]

Re: Severe Torque Steer To Port

I dont think it is a trim tab problem...... I dont even have one (Trim Tab) on my boat - 21' - alpha 1 - And i do not experience this when on plan and trimed up.

I would check for excesive play in your outdrive... something is loose or crack'd or missing or it's just plane wore out...

Do some checking as other have stated!

Good Luck!

 

[1960 Starflite]

Re: Severe Torque Steer To Port

Thanks for the replies. It will be a few days, but I'm going to remove the whale tail and have a helper hold the wheel while I try moving the outdrive at different trim angles. I can't do it at my boathouse, to deep to stand and I rolled the canoe over the last time I tried that, WOW that water was cold then. Either have to go to the sand bar (nope no beer at this one) or put it back on the trailer.

 

[1960 Starflite]

Re: Severe Torque Steer To Port

I took the whale tail off yesterday and had a helper hold the steering wheel. I felt only a little backlash in the rack and pinion steering cable. I felt very little play (if any) in both the verticle and horizonal hinge pins.

Took it out into the lake and there is NO difference in the steering, still pulls hard left after triming up a few degrees. If there is a hook in he hull, wouldn't it pull with the trim down?

I think I'll borrow a prop fom neighbor to see what happens.

Thanks for the replies.

 

[gking1937]

Re: Severe Torque Steer To Port

OK, I'm missing something with all this talk about props and motor holes. The OP said the tab is all the way to port, plus some driveway modification. If the image below is accurate, no freakin wonder he has to use two hands to port! Relieving pressure to port (steers easily to starboard) requires moving the tab to starboard. The steering initially pulls left because of prop torgue before the tab is effective.

OP, take off the hydro-foil, those things can mask far more problems than they solve. Then center the tab and go run it. There may very well be a difference in steering effort from trimmed down to trimmed up. When I had the problem, I adjusted the tab for minimum force (ideally 'none') when at speed with the engine trimmed out. Basically, if you have to hold pressure to port, move the tab to starboard, not further to port ... :facepalm:

Pardon me for jumping in this topic. I'm confused as to why the above drawing works. Looks to me like moving the tab to the right would cause the boat to steer to the right. Can someone educate an old ignorant fisherman?

Thanks in advance.
George

 

[NYBo]

Re: Severe Torque Steer To Port

Welcome to iboats, George!

I used to think exactly the same as you until someone here explained that what changing the trim tab does is change the direction of pressure on the outdrive, not the entire boat. Think about it: when the boat is turning to starboard/right, the outdrive is turned to the right. Moving the trim tab's rear edge to the right pushes the outdrive to port/left.

 

[gking1937]

Re: Severe Torque Steer To Port

Thanks Bob - makes perfect sense when you think about it!

 

["B"]

Re: Severe Torque Steer To Port

I have a question.....Regarding the pictures from GKing I can see that if your tab adjustment is at the rear of the tab then what is shown and what you say are true, but if the tab adjustment is at the front of the tab would you not adjust it to the opposit to counter the pull? I don't know that's why I'm asking. I set mine for neutral steer and it didn't change the starboard pull I was experiencing. I have radjusted it to oppose the original set up but was unable to test drive it so see what if any difference there may be. I don't have a power trim so it's kinda tough changing plane while running across the water. My engine is a Force 85HP the boat is a 1989 Spectrum aluminum hull sport/fisher. I tried to balance the weight evenly throughout the boat but that has no effect. This motor really gets this thing up on a suitable plane very fast but it pulls like crazy getting there. Once on plane if I let up on the steering wheel it just swings the boat to the right and I mean right now. Scarey stuff.....HELP!!!!!!!!!!!!!!!!!!!!!