Prop Torque

[tygh]

I am getting a lot of prop torque on my boat and even with weight distributed properly, the boat lists to starboard a bit and wants to wander that way.<br /><br />What is the best solution for overcoming this?

 

[Wimperdink]

Re: Prop Torque

need more info... i/o? outboard? I have an i/0 that had the same problem. I have a small trim tab above my prop that I adjusted to counter the action. Now tracks straight.

 

[CalicoKid]

Re: Prop Torque

Well hopefully it's prop torque. You can adjust the trim fin under the anti-vent plate if you have one. Are you an outboard or I/O? There could be a hook in your hull if this is an older possibly rotten or damaged hull.<br /><br />Tell us about the boat, Make, model, year, engine.

 

[tygh]

Re: Prop Torque

The boat is a new Triumph 170cc with a 75hp 4S outboard

 

[Jdeagro]

Re: Prop Torque

Also indicate if you are trimming the motor up when you get on plane? If it is an outboard, is the antiventilation plate even with the bottom of the boat? Are you running a hydrofoil?<br /><br />Torque list (not torque steer)is caused by the rotation of the motor (clockwise) which tends to make the boat list to the port side. If the bow is too far down in the water (too much keel in the water) the tendancy will be pronounced. Trim the motor up, remove the hydrofoil (if you have on, raise the motor if iot is too low.

 

[tygh]

Re: Prop Torque

The tendancy for the boat to lean to the starboard is when on plane. I do trim the motor up and the antiventilation plate is ieven with the bottom of the boat. I am not running a hydrofoil

 

[QC]

Re: Prop Torque

A couple of clarifications. nautiJohn said "Torque list (not torque steer)is caused by the rotation of the motor (clockwise) which tends to make the boat list to the port side". Actually it is the rotation of the propeller that causes the list. I am sure this is what he meant, but needs to be clear. Also, "clockwise" is viewing the propeller from behind it.<br /><br />The fact that your boat lists to starboard tells me that this is not prop torque. Are you saying that there is a noticeable list to Starboard when on plane vs. at rest in the water? This seems odd to me. How are you comparing the list? Maybe it just "feels" that way?

 

[tygh]

Re: Prop Torque

No, it is noticable. I even redistributed gear to try to offset the list but to no avail. Sits even in the water when anchored or moored. Up on plane, it wants to go to the right and the hull leans to the right. Passengers notice the lean as well.

 

[QC]

Re: Prop Torque

Does it do this when you are alone in the boat? i.e. weight would theoretically be even if you are alone in a Center Console . . .

 

[umblecumbuz]

Re: Prop Torque

Torque-steer is caused because the prop is effectively a screw trying to drive itself through a non-compressible medium - the water.<br /><br />As it 'screws' clockwise viewed from behind the boat, it tries to swing the leg to the left, pendulum-fashion. This causes the hull to assume an assymetric profile in the water, making it become its own rudder, and the result is that the boat tends both to lean and to veer to starboard. This tendency often gets worse with increased revs.<br /><br />The trim fin below the AV plate is designed to counteract this, and usually it does. But depending on the hull, the boat balance, the position of the leg in relation to the keel, and the shape of the prop, it sometimes needs further adjustment. Swing the trailing edge of the trimfin to the right to counteract the boat's tendency to veer right, and vise versa.<br /><br />Trinm tabs also help overcome this problem.

 

[QC]

Re: Prop Torque

SF,<br /><br />Maybe I can imagine this if the steering trim tab is VERY out of adjustment.<br /><br />Tygh, <br /><br />Do you have a particularly hard time steering in either direction? Particularly easy?

 

[tygh]

Re: Prop Torque

It turns particulary easy to starboard and I do feel more resistance when turning to port. The steering tab is all the way to the right.<br /><br />I may be putting some trim tabs on the boat if I cannot correct this another way.

 

[Jdeagro]

Re: Prop Torque

Thats what happens when I get to busy! Did not notice the list to Starboard - read right past it. Have you attempted to adjust the steering tab? Assuming it is an OB, is it the origional motor?