Strong pull to port while motoring

[gamayun]

While motoring (with sails up and without), my boat started pulling to port about 3 seconds after I let go of the wheel. This hasn't happened before. The bottom is clean and the prop looks in good condition. It walks to port in reverse so I assume if it were the prop, it would deviate to starboard in forward, right? Could this have something to do with the AP, though it was not on when this was going on. Could it be the rudder slipping? Any thoughts on where to start looking would be appreciated!

[HappyMdRSailor]

Originally Posted by gamayun

While motoring (with sails up and without), my boat started pulling to port about 3 seconds after I let go of the wheel. This hasn't happened before. The bottom is clean and the prop looks in good condition. It walks to port in reverse so I assume if it were the prop, it would deviate to starboard in forward, right? Could this have something to do with the AP, though it was not on when this was going on. Could it be the rudder slipping? Any thoughts on where to start looking would be appreciated!

Move your wife to the starboard side....

Just kidding.... New to you boat? When did it start...???? Details please!

[gamayun]

Originally Posted by HappyMdRSailor

Move your wife to the starboard side....

Just kidding.... New to you boat? When did it start...???? Details please!

...or it was the 2 big male crew I had on board that day (I'm female).

I've had the boat one year and it had not happened before this past Friday when we moved it up the coast. We probably motored 2 hours and sailed 5. I'm taking it out again on Wednesday and will see if anything has changed since I cleaned the bottom and put zincs on, but can't imagine that was the cause. I have not hit anything either. Was thinking that maybe the knob that can lock my wheel in place is really loose, but that still doesn't explain why it takes off like it does. It is a very strong and sudden turn. Maybe she just wants to go back to her old home port

[markpierce]

Originally Posted by gamayun

... It walks to port in reverse so I assume if it were the prop, it would deviate to starboard in forward, right? ...

WRONG. I have a left-turning (counter-clockwise) propeller. In reverse, there is significant prop-walk to starboard. Forward, the rudder needs a three-degree turn to port to counter forward prop-walk to starboard.

(Have rudder indicator; here while docked. When under power, I'm showing a three-degree rudder to port to maintain course. When coasting, the rudder needs to be returned to zero-degrees to keep straight.)

[CaptTom]

Mark, I believe you, but could you explain how that can happen?

My over-simplified understanding of prop walk was that the bottom of the prop "walks" more than the top, hence a right-handed prop walks to port in reverse, and starboard in forward. Something about the top passing close to the hull and the bottom being in undisturbed water. You can visualize this by imagining the prop is a rubber tire sitting on a paved road. You can tell by this description that I'm no engineer.

There are probably 1,000 other things that can result in a pull one way or the other; asymmetry in the rudder, fittings or fouling on the hull, lines wrapped around running gear, engine torque, windage, listing, etc. So I have no doubt you experience a force to starboard both ways. Just hard to see how they can both be caused by prop walk.

[markpierce]

Originally Posted by CaptTom

Mark, I believe you, but could you explain how that can happen?

I presume it's for the same reason there is prop walk in reverse, but less severe because water is being pushed around the rudder? I'm no scientist, but I attempt to take attention to what happens.

[speakeasy]

If your steering is hydraulic, you probably have a fouled up check valve in the helm pump. If not hydraulic, I haven't a clue.

[jeremiason]

Originally Posted by markpierce

WRONG. I have a left-turning (counter-clockwise) propeller. In reverse, there is significant prop-walk to starboard. Forward, the rudder needs a three-degree turn to port to counter forward prop-walk to starboard.

(Have rudder indicator; here while docked. When under power, I'm showing a three-degree rudder to port to maintain course. When coasting, the rudder needs to be returned to zero-degrees to keep straight.)

Mark you should read a little bit on Prop Walk before you tell someone they are wrong.

You do have prop walk in forward, just not as pronounced as when the boat is in reverse.

Try this.... Next time you are at a dead stop, place your boat in forward with the rudder amidships. The bow of your boat will turn away from the direction of the prop walk. It may be slight, but the prop walk will effect the forward movement of the boat.

Prop Walk is a great tool for docking and a prudent Skipper will use it to his/her advantage.

Someone did a great explanation of prop walk on Wikipedia here

[Pete7]

You may also find the builder has offset the propshaft so that it can be withdrawn from the stern tube without fouling the rudder. Prop normally needs to come off but the shaft will then just slide past the rudder.

Pete

[AKMark]

To be sure we understand:
It didn't behave like this until a recent trip? If so, that would probably rule out prop walk and/or structural reasons.

I'm guessing you have a mark on the wheel that is normally 'dead ahead'? When you motor dead ahead, do you feel a slight pressure turning the wheel to port? And when you let go, the wheel turns with increasing force to port?

My first guess would be something (crab pot, fishing net, etc.) fouled on your keel or rudder.

Second guess would be that steering cables are fouled inside the boat. Most sailboats this size have a cable/pulley contraption that translates wheel turns into rudder turns. The cable could be fouled on one side and/or the adjustment bolts could be coming loose.



I'd for sure figure this out before your next outing. It could lead to complete loss of steering, which can be quite unpleasant (and dangerous). Let us know what you find out.

Cheers

[gamayun]

Originally Posted by AKMark

To be sure we understand:
It didn't behave like this until a recent trip? If so, that would probably rule out prop walk and/or structural reasons.

I'm guessing you have a mark on the wheel that is normally 'dead ahead'? When you motor dead ahead, do you feel a slight pressure turning the wheel to port? And when you let go, the wheel turns with increasing force to port?

My first guess would be something (crab pot, fishing net, etc.) fouled on your keel or rudder.

Second guess would be that steering cables are fouled inside the boat. Most sailboats this size have a cable/pulley contraption that translates wheel turns into rudder turns. The cable could be fouled on one side and/or the adjustment bolts could be coming loose.

I'd for sure figure this out before your next outing. It could lead to complete loss of steering, which can be quite unpleasant (and dangerous). Let us know what you find out.

Cheers

That's right. It didn't behave like this before Friday. I dove the boat on Saturday and nothing was fouled, but your second suggestion might have actually hit on it. There is a bunch of rope from my old running rigging piled near my cable for the steering. I had been digging in there earlier that day looking for extra dock lines and had noticed the pile was getting a little unruly. Maybe something was leaning on the steering cable, which is on the port side... I'll be there tomorrow and will clean up that stuff. KISS, right? I'll also check the bolts while I'm contorted down there and then will be going for a quick sail. I'll keep fingers crossed that was it and will let y'all know! Thanks.

[HappyMdRSailor]

Originally Posted by jeremiason

Mark you should read a little bit on Prop Walk before you tell someone they are wrong.

You do have prop walk in forward, just not as pronounced as when the boat is in reverse.

Try this.... Next time you are at a dead stop, place your boat in forward with the rudder amidships. The bow of your boat will turn away from the direction of the prop walk. It may be slight, but the prop walk will effect the forward movement of the boat.

Prop Walk is a great tool for docking and a prudent Skipper will use it to his/her advantage.

Someone did a great explanation of prop walk on Wikipedia here

Tom... I think what Mark was trying to correct with the "WRONG" was the earlier statement that forward propwalk would cause the bow to move in opposite direction of your sternway propwalk It walks to port in reverse so I assume if it were the prop, it would deviate to starboard in forward, right?

i.e No, your bow would tend to move port in forward.... (if of course the OP was referring to the stern moving to port in reverse)

Originally Posted by gamayun

That's right. It didn't behave like this before Friday. I dove the boat on Saturday and nothing was fouled, but your second suggestion might have actually hit on it. There is a bunch of rope from my old running rigging piled near my cable for the steering. I had been digging in there earlier that day looking for extra dock lines and had noticed the pile was getting a little unruly. Maybe something was leaning on the steering cable, which is on the port side... I'll be there tomorrow and will clean up that stuff. KISS, right? I'll also check the bolts while I'm contorted down there and then will be going for a quick sail. I'll keep fingers crossed that was it and will let y'all know! Thanks.

Thanks for the update gamayun!

After you check for cable interference, check for any play from helm to ruddershaft movement... Give that cable a tweak tighter if it seems on the loose side... Also, we need to investigate if any steering component recently provides "less resistance" to helm correction... therefore providing less static resistance to the rudder forces...

Try a couple of opposite passes without canvas in some wind/current free(ish) water after your next investigation!

[woodymr]

If I may, my boat also pulls strongly to port ( pulling tiller to starboard). It has a 14 / 10 RH prop and a "barn door" size rudder and one day I suddenly thought it just started but it really always was that way I just did not notice it so much. It's like driving a stretch of highway many times and suddenly discovering something "new" that had always been there. I hope this this is it and no problems. Best Wishes,,,,/),,,,

[gamayun]

Originally Posted by woodymr

If I may, my boat also pulls strongly to port ( pulling tiller to starboard). It has a 14 / 10 RH prop and a "barn door" size rudder and one day I suddenly thought it just started but it really always was that way I just did not notice it so much. It's like driving a stretch of highway many times and suddenly discovering something "new" that had always been there. I hope this this is it and no problems. Best Wishes,,,,/),,,,

Hmm, that has actually been tickling the back of my brain. It is a fairly new-to-me boat, but super strange that it's never been noticeable before. I'm all for the "don't worry about it" attitude, if I really don't need to worry about it, but I'll check out everything tomorrow and will also ask some friends who have motored with me whether they remember anything like this. I really appreciate all the suggestions and the comments about prop walk.

[carstenb]

Originally Posted by gamayun

Hmm, that has actually been tickling the back of my brain. It is a fairly new-to-me boat, but super strange that it's never been noticeable before. I'm all for the "don't worry about it" attitude, if I really don't need to worry about it, but I'll check out everything tomorrow and will also ask some friends who have motored with me whether they remember anything like this. I really appreciate all the suggestions and the comments about prop walk.

If it hasn't sone it before and yo've never noticed it - it is not a function of prop walk.

More likely, your steering gear (rudder, cables, etc) have somehow been affected. If you dove the boat and there is nothing on the rudder, time to check the helm and steering gear in detail. Is the cable loose? any of the pins or bolts loose? etc etc. Start at one end and work your way through. This will be a contortionist nightmare, and you'll really wish you were 6 inches shorter and weighed 10 less (no matter how skinny or short you are :-) ), but has tone done. Losing your steering is nasty