Correcting for Torque Steering

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10forty2

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Well, we spent the last 5 days camping at the lake and riding on the boat. In an earlier post, I mentioned that I had installed fixed trim tabs to compensate for the inherent porpoising that comes along with the hull design of our boats. The trim tabs work GREAT to correct that. No more bouncing out of control. Now, however, the torque steering to port, that was slightly noticeable before the trim tabs, is now terrible with the trim tabs. It takes a great deal of steering effort to keep the steering wheel turned to starboard enough to keep on a straight course. If I let go, the wheel turns left and the boat will veer hard to port.

So, although it seems obvious that the trim tabs need some sort of adjustment, I am asking for all of the nautical engineers (tongue-in-cheek) on here to chime in with suggestions for WHAT adjustments I need to make.
 
Have you verified that both engine rpms are sync-ed?

I know on my 96 Speedster if they’re more then 100-200 rpm difference I have to countersteer to correct the lack of thrust on one side. If you’re constantly pulling to one side, a cable adjustment might be the fix you need.

If that’s not an issue, maybe the steering alignment?
 
Have you verified that both engine rpms are sync-ed?

I know on my 96 Speedster if they’re more then 100-200 rpm difference I have to countersteer to correct the lack of thrust on one side. If you’re constantly pulling to one side, a cable adjustment might be the fix you need.

If that’s not an issue, maybe the steering alignment?

Thanks! Yes, both engines appear to be in sync, as far as RPMs are concerned. Before adding the trim tabs, I would intentionally vary the RPMs about 200-500 on each engine underway (IE., port at 6K and starboard at 5.5 or lower) and it seemed to help with the porpoising....never noticed much of a torque steer effect when doing that, though. But after adding the trim tabs to correct the porpoising, I can run both throttles even and the RPMs are nearly identical (give or take a few)....it just pulls VERY hard to port.

Which cables to adjust? Steering? There doesn't seem to be a problem at low speeds, only when I am running around 25-30mph and planed out. It takes a hard starboard steering correction to maintain straight. In other reading this morning, I've seen reference to the stator vanes being bent or damaged? If so, which side would cause the port deflection?
 
I was referring to the throttle cables not steering.

Check your shop manual for steering adjustment. I don’t know if the admins allow parts of the manual to be copy and pasted in threads cause it’s part of the premium subscription, which I highly recommend btw.

If you’re worried about the integrity of the pumps, best thing to do is pull them and give them a good once over. I’m nowhere near as experienced as some of the other members on here, while diagnostic help is great, it can’t replace getting eyes on the part. They’re not hard to remove at all, just remember to use a new neoprene seal!
 
Gotcha! No, I don't think it's an uneven thrust issue. It seems more of either a drag issue or a misaligned thrust nozzle. I checked out the vanes at lunch...just a visual through the nozzles, and they look almost pristine on the trailing edge, as well as the impellers' trailing edges look fine. There is no lack of forward thrust, just seems misdirected. I'll look up the procedure for aligning the nozzles and check them to make sure they are both pointed straight. The linkage seems to be solid, but I guess it could have gotten turned over the years.
 
Checked nozzle alignment and all is correct. In case anyone is wondering how to do that, the manual spells out a VERY specific procedure to check alignment..............wait for it............ set the steering wheel stright and use a straightedge to make sure that both nozzles are lined up correctly. If both sides of each nozzle touches the straightedge, then guess what? They are aligned properly...... so yeah, I did that and both nozzles are aligned properly. On better visual inspection with a better flashlight, all the vanes look great, and the leading and trailing edges of the impellers don't even looked slightly chipped. I guess my next step is to do some adjusting to the trim tabs I added. I'm thinking since it pulls to port that the down-angle of my port tab needs to be reduced to produce less drag on that side. I'll be at the lake for a few days, so I guess it's a good time to make some adjustments.....especially since I have her on the market for sale! Don't want a potential buyer to be scared off of this fine machine because of an add-on I made.
 
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