How can I reduce Severe Prop Torque

DJS · 31 August 2010, 10:17

Hi Folks

I am suffering severe prop torque (I assume) in essence all the boat wants to do is turn right! I can manage left turns with a fair bit of effort, but my good wife finds it near impossible.

I have checked the steering etc and disconnected the link form the outboard and all is free, it is on a Teleflex cable system (not sure how old the cable and helm are) and I have thought of replacing it with a ‘no feed back system’ or maybe even hydraulic; any advice and guidance is welcomed!!

Thanks
DJS

JABS · 31 August 2010, 10:31

There will be a trim tab mounted vertically above the prop, probably an anode.

Move it over to the left a few degrees and try again!

I had exactly the same issue.

It is a bit of trial and error, but worth the effort.

will_m · 31 August 2010, 10:38

Quote:

Originally Posted by DJS

and I have thought of replacing it with a ‘no feed back system’ or ...

After many years of putting up with a regular cheapy steering head, on my Ribtec, first with a Honda 90 and subsequently now with a Yam 100..

I know exactly what your saying!!!!

Even with the trim fin/skeg whatever you call it adjusted fully over to counteract the torque-steer, the steering was rubbish. After a day out I’d have one shoulder aching like bas****.

So a couple of years back bunged on a NFB steering head. Why oh why I didn’t do this years ago!!!!!!!!!

Total transformation of the steering, light, will stay straight ahead, no pulling to the right what so ever.

NFB = Poor man’s power steering!!!!

For such an inexpensive bit of kit and an hour or so of your time to junk the current steering head and swap it for the NFB, you will wonder why you didn’t do it ages ago.

Bigmuz7 · 31 August 2010, 10:41

And be sure to use a kill cord, and check the operation of your kill switch because this type of torque has nasty consequences if you were to let go the helm

9D280 · 31 August 2010, 11:24

Quote:

Originally Posted by JABS

There will be a trim tab mounted vertically above the prop, probably an anode.

It is an anode, and therefore will corrode - especially if your boat stays afloat for a good chunk of the year.

If you can, it's worth comparing it to a similar engine, as corrosion will reduce it's area and therefore reduce its effectiveness. I had a similar thing on a seconhand Yam 55. A new anode made a world of difference.

If that's the case, mark the underside of the cav plate with a pencil so you can put the new one back where the old one came from. (assumes of course it was set uip correctly in the first place.!)

DJS · 31 August 2010, 11:36

Hi Folks thanks so far for all the advice so far and I have adjusted the trim tab in varying degrees to no avail, hence it sounds like a change of steering or steroids!

9D280 · 31 August 2010, 15:06

I have no idea of the history of your engine, but have a look along your skeg / cav plate "wings". They may not all be as straight as they came out the factory?

(Granted, unlikely if you've owned it since new & never hit anything!)

Also just as a sanity check, this does only happen at speed?

JABS · 31 August 2010, 15:42

It may be worth looking at the offset?

Is the engine on the centreline of the boat?

Try and look at other identical ribs with similar engines.

jyasaki · 31 August 2010, 16:39

Quote:

Originally Posted by 9D280

It is an anode, and therefore will corrode - especially if your boat stays afloat for a good chunk of the year.

If you can, it's worth comparing it to a similar engine, as corrosion will reduce it's area and therefore reduce its effectiveness. I had a similar thing on a seconhand Yam 55. A new anode made a world of difference.

On my engine, the trim tab/anode seems to decay more by doing a swiss cheese imitation than by gradually getting smaller and shorter. Then again, I've adjusted mine all over and can't see that it does a hell of a lot with respect to prop torque anyway.

Quote:

If that's the case, mark the underside of the cav plate with a pencil so you can put the new one back where the old one came from. (assumes of course it was set uip correctly in the first place.!)

Sharpie or a dab of paint would be better, assuming you've found the ideal setting.

I agree, with other posters, though: sounds like a No-Feedback helm is what the OP needs.

jky

Searider · 31 August 2010, 22:45

Does the steering pull vary with trim angle?

Normally does such that at any particular speed you can adjust the trim to give neutral light ish steering.

Bigmuz7 · 31 August 2010, 22:56

Quote:

Originally Posted by JABS

It may be worth looking at the offset?

I'm interested in this point because I had a 135 merc that was a bitch for this problem but I never checked the offset

Quote:

Originally Posted by jyasaki

sounds like a No-Feedback helm is what the OP needs.

But Ive got a nice 75 that runs as straight as a die on cables no problem what so ever

DJS · 02 September 2010, 17:32

Thanks for all the advice and it has confirmed my intended solution to install a NFB steering system and any advice regarding the use of a 3 turn or the 4.2 turn option is welcomed

Cookee · 03 September 2010, 08:36

Quote:

Originally Posted by DJS

Thanks for all the advice and it has confirmed my intended solution to install a NFB steering system and any advice regarding the use of a 3 turn or the 4.2 turn option is welcomed

4.2 will be easier to turn but take longer to steer.

Hightower · 04 September 2010, 12:47

If you're going to install a new steering system then the 4.2 turn one is a better bet in my opinion as Cookeee has suggested.

However you still haven't mentioned whether you had this same problem with different trim positions?

DJS · 04 September 2010, 14:09

The steering does get a little lighter the higher the trim angle but you would have to be right at the top of the trim height.

Pikey Dave · 05 September 2010, 21:40

Have you got the engine height set correctly? The AV plate should be about 1" above the water when planing. If you are set too low, more of the gearbox is in the water increasing the drag.

DJS · 06 September 2010, 06:58

Quote:

Originally Posted by Pikey Dave

Have you got the engine height set correctly? The AV plate should be about 1" above the water when planing. If you are set too low, more of the gearbox is in the water increasing the drag.

Hight and mounting position all look good!

GRAHAM SOMERS · 06 September 2010, 16:34

For standard engine installation on RIBs particulary with higher powered outboards is to offset the engine by between 1inch-2 inches to the right (starboard side). This will help the torque problem. The variance depends on the engine size, but in your case check the position of the engine. If it has been installed bang in the middle of the transom I would then recommend you move it 1 1/2 inches to the right.