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ContinuousWave: Whaler Repairs/Mods
Boat pulls to starboard (steering torque questions)
|Author||Topic: Boat pulls to starboard (steering torque questions)|
posted 06-04-2002 05:29 PM ET (US)
My 13' with a 40 hp Johnson pulled to the right at various speeds, no matter how I adjusted the fin above the propeller. It seemed that if I turned the fin (does the fin have a name?) all the way to the right, it would almost stop the pull to the starboard. That seemed backwards to me, because if I stuck a paddle in the water off of the starboard side, the boat would pull more to starboard, not less. Right? Anyway, when that did not completely stop the pull I ordered a Sting Ray stabilizer and the accessory parts to stop steering torque. After several adjustments, I no longer have a pull at speeds higher than 20 mph, but I do have a pull at speeds lower than that. And I dare not take my hand from the wheel for a split second for fear that the boat will make a hard turn to the right.
Here are my questions: Am I turning the fin the right way? Can I order a larger fin and do away with the Sting Ray product? If I replace the original cable/pulley steering with teleflex NFB or hydralic steering, will this help to eliminate the problem? If I replace my 3-blade propeller with a 4-blade propeller, will I experience less steering torque? Thanks!
posted 06-04-2002 07:28 PM ET (US)
Is that little fin called a trim tab? Its seems to me that its acting like one. Adjusting the tab/fin to the right would force the engine to the left, which would counteract the torque steer to the right. (when viewed from the stern).
Sounds like you might have a tilt/trim problem. I've noticed on my boat that the torque steer is really bad until I trim up (out). Of course that's easy with power T&T.
posted 06-04-2002 09:52 PM ET (US)
Does your motor have an adjustment to tighten up the amount of force it takes to turn it? Might be too loose. I installed a teleflex NFB steering on my 13'er when I installed my new Honda, I can now set the steering and take my hands off of the wheel and won't very my course except for wind and current changes, in fact it's a little on the stiff side, I wouldn't mind if it loosens up a little with use.
|Tom W Clark||
posted 06-04-2002 10:02 PM ET (US)
I agree with Taylor. The trim tab steers the motor, not the boat. The motor steers the boat. If the trim tab is adjusted with its trailing edge to starboard this will push or “steer” the gearcase's trailing edge to port and reduce the prop torque.
It sounds like you have the motor trimmed in too far. If it is set at it lowest tilt pin adjustment, move it out one hole. You want the cavitation plate to be more or less parallel with the water when running. If you have power trim, then try trimming the motor out.
When the motor is trimmed in so that the axis is the prop shaft is out of alignment with the water’s surface then the propeller blades have a greater angle of attack on their down swing on the starboard side and a reduced angle of attack on the upswing on the port side. Thus there is greater thrust in the starboard side of the motor's center line and the motor will pull to starboard.
posted 06-04-2002 10:26 PM ET (US)
I understand now why turning the trim tab to starboard turns the boat to starboard. Thank you! I'll experiment with trimming the engine out another notch--right now it is in the middle position (i.e., the pin goes through the third of five holes). I have no idea if I can tighten the steering as Browning suggested--I'll investigate. Excellent suggestions. Thank you!
posted 06-04-2002 10:32 PM ET (US)
Correction--I meant to say that I understand why it KEEPS the boat from turning to starboard :)
Does the type of steering or the number of blades on the propeller make any difference?
posted 06-04-2002 11:39 PM ET (US)
I would start the trim tab in a neutral position and then trim the motor out one hole as suggested. Then adjust as neccessary. I found on my 70 hp Johnson when I moved the thrust rod away from the transom the boat tended to steer towards the port side.
posted 06-06-2002 12:53 PM ET (US)
With regards to the NFB systems, NFB is not supposed to transmit the torque to the wheel. It should be much better than the original system. NFB=No_Feed_Back.
posted 06-06-2002 05:13 PM ET (US)
Thanks for the feed back on NFB teleflex cables:) In another thread there was some speculation that having more than three propeller blades also reduces steering torque. Is this a fact or a theory?
posted 06-06-2002 07:52 PM ET (US)
If the pitch of the multi-bladed prop is less than that of your existing three blade,then yes, there will be less torque.
Steering torque is caused by p-factor, which occurs when the thrust line of the propeller is not the same as the oncoming water flow.When your motor is trimmed in, the down-going blade is at a greater angle of attack on the right side of the prop (viewed from behind). This results in more thrust on the right side of the prop, forcing the motor to the right,causing a right turn.The more pitch the prop has, the more it aggravates this condition.
posted 02-07-2010 05:26 PM ET (US)
I have the same problem with my dual engine boston whaler, and was wondering if the problem is corrected differently under those circumstances?
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