torque twist / 85hp on 16ft Skeeter

[jasonh]

I previously posted a question regarding a bent skeg and the effect it could have as far as making my boat pull to the left. General concensus was that it could not have as strong an effect as I was experiencing. There remains a bushing issue that I feel will help, but am not convinced it will eliminate the problem. Someone mentioned torque-twist, so I searched for more information about that with no luck.

My basic question is this - on a 16ft boat with an 85hp motor (which is the maximum HP recommended), could I be over-powered to a degree where the natural twist action of the motor at speed is causing this left-ward leaning and subsequent turning? My boat is an older Skeeter with stick-steering. It's not all that "substantial" as far as heft. I never experienced anything like this with the 65hp I previously had on there, so this is really bugging me. I spent a good chunk of change buying this motor and having it tuned up, so not being able to run it out at 35mph without feeling like it's trying to flip over is disconcerting. Also, could the steering system be the culprit here? The stick-steer mechanism is simply a box with a wheel inside the cable attaches to. I can easily turn the motor from side to side standing behind it, making the stick move back and forth. I have a steering wheel removed from an old Glastron that has the rack and cable and everything. It seems a lot stronger and capable, but converting my boat to this steering system would be quite a project, not to mention the expense of buying a new, longer cable since I'd have to mount it way up front where my controls are. So if anyone has any thoughts or previous experience with something like this, I'd appreciate any advice I can get.

 

[ezeke]

Re: torque twist / 85hp on 16ft Skeeter

Did you ever try moving the back of the trim tab to port?

 

[levittownnick]

Re: torque twist / 85hp on 16ft Skeeter

You increased HP by 30%, it may not be over-powered but it certainly will make a difference. As for the question posed, I don't have a clue.

 

[jasonh]

Re: torque twist / 85hp on 16ft Skeeter

I did move the trim tab to port and there was no effect. I centered it and am leaving it there for the time being.

 

[steelespike]

Re: torque twist / 85hp on 16ft Skeeter

Assuming the motor is set up right especially verticle height.
If your boat is leaning it is usually a result of prop torque
or a hull problem.Have you used a straight edge on the bottom to check for a hook or other deformity in the bottom?

 

[jasonh]

Re: torque twist / 85hp on 16ft Skeeter

No, that never crossed my mind but I'll give it a look-see.

 

[DHPMARINE]

Re: torque twist / 85hp on 16ft Skeeter

First thing ... is the motor centered on the transom ?

Beyond that OMC had a Service Advisory (I think) years ago saying the could not support "stick steering" on their boats,at any HP rating.I certainly would not want to try controlling 85HP that way anymore than I would put tiller cable and pulleys on that much HP.

A new helm and cable kit is less than $175,but you'll also need a steering wheel and hardware to connect it to the motor.

Good Luck

DHP

 

[emdsapmgr]

Re: torque twist / 85hp on 16ft Skeeter

The torque twist on larger engines causes the two problems you notice. The engine pulls to the right. All boats have this problem. Engine torque steer won't go away, but you can mask it by changing out the steering. "No feedback" helms hide the problem. Newer hydraulic systems also correct the problem. Not an easy/cheap fix. Torque steer also can cause the boat to lean to one side. (ever wonder why the steering wheel is on the right?) Narrower boats may magnify the problem, also some hulls are more suseptible. I ran a 100 hp 16' fiberglass boat for years with the lean problem. Corrected when I moved the engine to another boat. Possible that a small 6" trim tab on one side of the transom might provide some help.

 

[Dhadley]

Re: torque twist / 85hp on 16ft Skeeter

A bent skeg certainly can magnify the torque problem. The skeg plays a very important part in eleminating torque in the wheel, or in this case the stick.

Steering torque is a by-product of the fact the prop turns a given direction. Clockwise or right-hand in this case. The motor tries to lay over as you gain speed (prop rpm). To offset this we use the little tab above the prop commonly called the "trim tab".

If the boat wants to pull to the right, you move the tab to the right. The higher the technology of the bottom design, the higher you can run the motor. At some point the little tab will no longer have the desired effect to counter the torque. This is when we start to play with the skeg.

Start by making sure the skeg is straight and all there. If it's worn, replace it. Make sure the motor is mounted in the center of the running surface, which may or may not be the center of the transom. Make sure the motor is straight up and down to the running surface. Which, again, may or may not be straight to the top of the transom.

If the tab on the motor has no effect, look into installing a torque tab on the skeg. I'm sure they sell them here at iboats. They're made by several folks like Bob's Machine. It's a little tab that screws to the skeg. You can bend the skeg but unless you've done it before you're better off adding the tab.

Steering torque is felt in the system because the gearcase is running crooked in the water. Get the gearcase to run straight and the torque will be gone. And when it's running crooked, it's scrubbing off speed. It's not unusual to get rid of the torque and pick up a couple mph.

Trim angle also has a lot to do with it. At some point in the trim range you'll find a neutral torque area. It may or may not be the fastest speed for that rpm. That's why we have to try to eleminate the torque, not just mask it with No Feedback or hydraulic steering. Masking it doesn't eleminate it, it just hides it.

I had a V4 looper on a 15' Allison that ran 82 in the 1/4 mile. It had no torque in the steering what so ever. I've had a V6 with over 325 hp on a tunnel boat that had no torque in the steering. Getting rid of the torque also takes the stress off of the steering system.

 

[jasonh]

Re: torque twist / 85hp on 16ft Skeeter

Thanks for the info on this. Its confirmed what I suspected - I need to lose the stick-steer setup. I have a steering assembly already that I will begin making plans to install. With the rack and pinion design, I can see where most of the feedback could be eliminated as opposed to my current system that faithfully relays any pull or motion back through the cable to my left arm.

My boat is on the narrow side, so it may always be somewhat of an issue. I will check out the skeg-mounted tab. Also, the motor was mounted using the same holes from where the previous motor mounted. I took it for granted it was centered, as I never had an issue with the 65 hp.

 

[CrappieLimit]

Re: torque twist / 85hp on 16ft Skeeter

I previously posted a question regarding a bent skeg and the effect it could have as far as making my boat pull to the left. General concensus was that it could not have as strong an effect as I was experiencing. There remains a bushing issue that I feel will help, but am not convinced it will eliminate the problem. Someone mentioned torque-twist, so I searched for more information about that with no luck.

My basic question is this - on a 16ft boat with an 85hp motor (which is the maximum HP recommended), could I be over-powered to a degree where the natural twist action of the motor at speed is causing this left-ward leaning and subsequent turning? My boat is an older Skeeter with stick-steering. It's not all that "substantial" as far as heft. I never experienced anything like this with the 65hp I previously had on there, so this is really bugging me. I spent a good chunk of change buying this motor and having it tuned up, so not being able to run it out at 35mph without feeling like it's trying to flip over is disconcerting. Also, could the steering system be the culprit here? The stick-steer mechanism is simply a box with a wheel inside the cable attaches to. I can easily turn the motor from side to side standing behind it, making the stick move back and forth. I have a steering wheel removed from an old Glastron that has the rack and cable and everything. It seems a lot stronger and capable, but converting my boat to this steering system would be quite a project, not to mention the expense of buying a new, longer cable since I'd have to mount it way up front where my controls are. So if anyone has any thoughts or previous experience with something like this, I'd appreciate any advice I can get.

I have used a couple of boats with stick steering. I have found that by adjusting the trim and tilt, you will find a sweet spot that will give you control both ways on your stick. There is another adjustment that can be made to the adjustable trim tab (little fin sticking down over your prop.) You might want to turn the back of the fin to the left in small increments.( If that makes it worst, adjust to the rignt).

 

[tashasdaddy]

Re: torque twist / 85hp on 16ft Skeeter

it sounds like you need to adjust time, sounds like it is kicking the bow down, causing it to dig in.