Strange Steering/Tracking Problem

[Sojourner]

So my Amel Super Maramu doesn't track straight all of a sudden... Meaning the wheel is at vertical and the boat slowly turns to starboard. See pic for the angle I need to keep her straight on a day with zero wind or current, motoring along.... Also, it used to be I could set the wheel to straight ahead and it would hold that track for miles on a calm day. But even if I put the rudder at center, it slowly turns starboard...

Just had the hull cleaned and it had been quite dirty, but I don't see a connection. Noticing prop walk in forward with a fresh clean hull? It's a saildrive coming out of the keel so prop walk is very minor either ahead or astern... so what can it be? Where should I start looking?

Note: I was diving all over the hull for two days prior, nothing hung up or visible to cause drag. Little help please??

[Sojourner]

Forgot the pic: This is the angle to hold her straight, about 15 degrees to port...

[Suijin]

Just to be clear, you’re saying that if you drive a straight line, now with the wheel a bit to port so she goes straight, release the wheel and she still still edges to starboard afterwards?

[gmakhs]

The steering system is hydraulic or with wires ??

[Sojourner]

Originally Posted by Suijin

Just to be clear, you’re saying that if you drive a straight line, now with the wheel a bit to port so she goes straight, release the wheel and she still still edges to starboard afterwards?

Yup, driving straight with the wheel at the position in the pic, then let go, the wheel will recenter itself slowly (the wrapped spoke in the pic above will turn clockwise to vertical in 5-10 seconds, and stay there, which tells me that the rudder is still aligned) but then the boat will slowly turn to starboard.

Just started after the short haul to clean a lot of growth off the hull (or I just noticed it). Lift went smoothly, good crew, lifting at the chainplates where you're supposed to, in and out in an hour.....strange, huh?

[Sojourner]

There's a transducer on that side that sticks out (see pic, the red one) but surely that isn't enough drag to turn this boat so quickly....? And why didn't I notice it before if so?

[gmakhs]

I believe the problem is with your rudder hydraulic system or the cables , so the rudder moves even if you have the wheel straight .

[Suijin]

Originally Posted by Sojourner

Yup, driving straight with the wheel at the position in the pic, then let go, the wheel will recenter itself slowly (the wrapped spoke in the pic above will turn clockwise to vertical in 5-10 seconds, and stay there, which tells me that the rudder is still aligned) but then the boat will slowly turn to starboard.

So you have cable steering. And the rudder is aligning with water flow, and then the boat veers to starboard. I assume this is under power. Are you certain there was no current flowing?

I'm completely stumped. I don't see how it could be anything other than something dragging. All I can suggest is that the boat was more foul on the port side before it was cleaned lol. That can happen if it's been sitting in a slip for awhile. I'm mostly kidding but you never know.

[Sojourner]

Originally Posted by gmakhs

I believe the problem is with your rudder hydraulic system or the cables , so the rudder moves even if you have the wheel straight .

Not quite understanding this... if I hold the wheel in the "new" straight position, she continues ahead under full control, but with a little feeling of weather helm (without the weather of course). If the rudder straightens out (assuming it's centered when the wheel is centered) then why would it continue turning?

If one of the hydraulic pistons lost some fluid/pressure, could this be a symptom? The other side overcompensating at it's 'normal' pressure?

[Sojourner]

Also, I'm an idiot... cable drive. I wonder if anything in the lazerette the cable runs through could be mashing it... Still dont get why the straight center rudder will make the boat turn slowly starboard tho... ie I have to hold the wheel with a little force (weather helm) 15 degrees to port to get it to go straight. Cable or hydraulic, that doesn't make sense...

[Sojourner]

Originally Posted by Suijin

So you have cable steering. And the rudder is aligning with water flow, and then the boat veers to starboard. I assume this is under power. Are you certain there was no current flowing?

I'm completely stumped. I don't see how it could be anything other than something dragging. All I can suggest is that the boat was more foul on the port side before it was cleaned lol. That can happen if it's been sitting in a slip for awhile. I'm mostly kidding but you never know.

I doubt current cause fouled before or not, the boat used to track straight back and forth up the bay from our usual slip to out to sea and back....we've done it hundreds of times, I would have noticed by now. It is really apparent hand steering when I tried to light a smoke. took my hands off the wheel for 10 seconds, I was facing a new direction...I smoke too much to not have noticed before!

[Suijin]

Originally Posted by Sojourner

took my hands off the wheel for 10 seconds, I was facing a new direction

Wow, that's a pretty dramatic "drift".

The easy cheap solution is to get faster at lighting your smokes.

[gmakhs]

Originally Posted by Sojourner

Not quite understanding this... if I hold the wheel in the "new" straight position, she continues ahead under full control, but with a little feeling of weather helm (without the weather of course). If the rudder straightens out (assuming it's centered when the wheel is centered) then why would it continue turning?

If one of the hydraulic pistons lost some fluid/pressure, could this be a symptom? The other side overcompensating at it's 'normal' pressure?

I think yes , lower pressure could be a symptom.

[Peregrine1983]

Does she track straight under sail? Is this more severe at full power under motor? I'm wondering if you're just noticing prop walk, although it sounds kind of extreme.