Terrible Torque steer

[Chop269]

I have a 1986 johnson 30hp tiller on my Lund 14ft deluxe. I just bought the boat and had it on the water for the first time this weekend. The torque steer is terrible and I feel very dangerous. I got the boat so my son could go fishing on his own but not until I fix the issue. What can I do? This motor does not have an adjustable tab on the lower unit. Is this something I can add and where would I find one. Please help.

 

[Still Afloat]

Perhaps the trim tab is just missing? I think it would be odd that a 30 hp would not have one.

 

[DaleH]

Perhaps the trim tab is just missing? I think it would be odd that a 30 hp would not have one.

No adjustable fin on that year OB. But use the 2 existing holes in the vent plate for the anode and make a small fin out of 1/8" angle aluminum stock. One leg 1" (for the bolts) and the other leg 1-1/2" tall (for the fin). See concept sketch. The 'slotted' hole allows for adjustment.

Also make sure your steering tension is up, you don't want that OB turning on its own under power ...



Put the fin below the plate and the anode on top of the plate, You'll need longer bolts for the anode.

 

[airshot]

Can't understand why one is not already on there, I have saw motors with a flat anode disc with no fin and often see where they have fallen off. Look under the cav plate and see if there is a spot for one, a round hole mabey 1 1/2" in diameter with a hole in the center ??

 

[DaleH]

.. don't recall seeing any 'adjustable' fins until up to ~60hp OBs myself. My old OMC 60hp had one, see photo from the 1996 OEM Service Manual, gearcase section.

 

[DaleH]

FYI … Whereas I had only added a small ‘fin’ thing like that on a 15hp on an inflatable, I figured I had better check with Pappy to see if it would work on a 30hp on a light 14’ skiff. Here is what he had to say:

“Sure, why not. The key to making it work is to let whoever it is know that this will work reliably until the trim angle changes. If that happens the steering angle of the blade will have to change. Neutral steering with a trim tab will only occur at one fairly narrow trim range.

Think of a propshaft that is exactly parallel with the waterline. Picture the side view of the propeller. Both the top blade and the bottom blade are perpendicular to the waterline and are pulling together. This is a neutral torque scenario.

Now, picture the side view of the propeller when trimmed down or under. The bottom blade is in front of or leading the upper propeller blade. That leading blade is rotating to the left, correct? Torque will change depending on which blade is the leading blade and what direction of rotation that leading blade is going in. Picture positive trim or trimmed out. Side view says upper blade is now the leading blade. It is rotating to the right.

Bigger the propeller the more steering torque is developed. On an airplane this phenomenon is called "P" factor. Quite noticeable on a taildragger!”

 

[jonboatsam]

FYI … Whereas I had only added a small ‘fin’ thing like that on a 15hp on an inflatable, I figured I had better check with Pappy to see if it would work on a 30hp on a light 14’ skiff. Here is what he had to say:

“Sure, why not. The key to making it work is to let whoever it is know that this will work reliably until the trim angle changes. If that happens the steering angle of the blade will have to change. Neutral steering with a trim tab will only occur at one fairly narrow trim range.

Think of a propshaft that is exactly parallel with the waterline. Picture the side view of the propeller. Both the top blade and the bottom blade are perpendicular to the waterline and are pulling together. This is a neutral torque scenario.

Now, picture the side view of the propeller when trimmed down or under. The bottom blade is in front of or leading the upper propeller blade. That leading blade is rotating to the left, correct? Torque will change depending on which blade is the leading blade and what direction of rotation that leading blade is going in. Picture positive trim or trimmed out. Side view says upper blade is now the leading blade. It is rotating to the right.

Bigger the propeller the more steering torque is developed. On an airplane this phenomenon is called "P" factor. Quite noticeable on a taildragger!”

Two thing you want to check, first make sure the that the tilt isn't to low which would make the nose of the boat go down plowing, second make sure the the motor is in middle of boat 3rd make sure the length of the motor is not a long shift. Raise tilt pin to 3rd hole for a start and adjust out 1 hole at a time.

 

[Montana300]

It's really as simple as the fact that you have a fairly powerful motor on a little boat so prop torque effect will be magnified.On my 14' with its 15HP motor I experienced significant prop torque, including an adrenaline-inducing moment on its first outing when I momentarily let go of the tiller at speed and instantly turned sharp right! The issue was a steering tension nut that was too loose. I suspect that's your issue too, so I'd address that before messing with adjustable trim tabs that are unlikely to solve your problem.

 

[DaleH]

True, steering friction should always be UP enough to prevent errant operation if you let go the tiller.

And knowing a guy who got run over by his OWN boat after he fell out ... only to live as my Mother put her hand into his inner thigh to clamp the cut artery closed (She didn't remove it until he was on the operating table and the Dr.'s said "You can pull out your hand now ... ") ... wear your ignition kill lanyard!

 

[wmk0002]

I've ran into this problem a few times and the tab never helped much. In all cases I made very slight adjustments to the outboard on the transom left or right and it fixed it. Obviously cant do it on a bolt on motor but yours being a clamp on you can. Sorry, I know it's not very helpful answer.

 

[thill]

The answer is probably in the suggestions above. I would follow them in this order:

1) Tighten up the steering tension screw and see if it changes. That should help a lot.
2) Raise the trim angle by one hole, then another and see if things change.
3) Scoot the motor slightly left or right and retest to see if things change.

One other not mentioned is,
4) Be gentle when accelerating. Don't just crank the throttle, but ease into it. As you gain speed, keep accelerating smoothly.

My first tiller motor, the Evinrude 25 in my sig pic, felt scary at first, like a living thing in my hand trying to break free. Almost out of control. Two things helped, #1 and #4. Once I got used to it, I didn't even think about it anymore. I think you will be the same.

 

[sonny.barile]

If your motor sits too low in the water then you will also pick up tons of torque steer from dragging the plate in the water. Try raising the motor a little so your plate is just at the surface while at WOT.