Boat pulling to starboard while underway.

[ryastu]

Purchased a 42' CHB trawler last year. Pretty much jumped in cold to owning a boat this big and just started learning on the fly. All in all went pretty well. However, one thing I have yet to pay much attention to is the hydaulic steering system. I noticed last summer that it would pull slightly to starboard (1 to 2 degrees) so in order to maintain a straight course i would need to give it 1 to to 2 degrees of rudder to port, as summer gave way to fall, I noticed by November the pull had increased to 3 to 4 degrees, and by February it appeared to have increased again to 6-7 degrees.

The steering system is a hydraulic system with two helms and two rudders. I'm identifying the degrees of helm I'm giving it based on the rudder angle indicator on the auto pilot, as that is the only rudder angle indicator I have (that has functioned since I have owned the boat). Note that the problem exists regardless of whether I'm steering with auto pilot or manual. What should I be looking for in the steering system that would cause this problem? I've done a decent amount of research and have found very little information; or should I be looking at variables outside of the steering systems, boat weighting, or marine growth?

I appreciate your thoughts and comments in advance! -Ryan

[Comodave]

Not sure but the easiest thing to check is the fluid level in the steering. Not sure if this could cause this problem but it is easy to check.

[SteveK]

single or twin engines? Twins could affect steering if the prop rpm is not the same with the correct props.
Maybe all you need is to bleed some air out of the line. How, you will need to research or get a boat mechanic.

[ryastu]

Yeah, it is a twin engine.....

[Endeavor GB 32]

Maybe the rudder angle indicator is off. Check the linkage in the lazarette.
Regards,
Scott

[SteveK]

Originally Posted by ryastu

Yeah, it is a twin engine.....

Is the boat actually turning to starboard or just the rudder indicator?
describe how you sync the engines.

[ryastu]

The boat physically veers to starboard when the rudder angle indicator reads, '0'.

When you say, 'sync the engines', I bring them up to speed and am running them at equivalent RPMs.

[SteveK]

Originally Posted by ryastu

The boat physically veers to starboard when the rudder angle indicator reads, '0'.

When you say, 'sync the engines', I bring them up to speed and am running them at equivalent RPMs.

OK, besides bleeding air from hydraulics, try this.

Get boat to speed, set up rpm as you have been doing, then add 50-100 rpm to starboard, note results and rpm.
To save time if it still veers, add another 50-100 until it tracks.
You can steer a boat with twins. The engines may not be in sync at same rpm on tach.

On mine I can track with upper tach the same rpm, I go to lower helm and they are 150~ rpm different. I first noticed this when setting both lower to same rpm, listening to engines and watching the boat veer off course.

[ryastu]

As we talk through this, I should have mentioned I did try this back in February, my log notes are below. One thing I have not done is looked at the upper and lower helms to verify consistent RPM readings.

○ Messing with engine RPM to see how it effects rudder angle while running on auto pilot:

@2400 port and Star at 2800, it still steers to the port, seems to bounce between 2 and 5 degrees to steer a straight course

@2200 port and Star at 2800 ,it still steers to the port, seems to bounce between 1 and 4 degrees to steer a straight course

@2000 port and Star at 2800, it still steers to the port, seems to bounce between 0 and 3 degrees to steer a straight course

[porman]

Try this. Find out how many turns lock to lock, then turn it back half that amount. The rudders should now be centered. Does the boat track straight? If it does, what does the rudder indicator say? If it isn't straight then it needs adjusting.

[ryastu]

Thank you, that's a good thought!

[SteveK]

400, 600, 800 rpm difference I would expect it to sound awful and steer port. The auto pilot is getting a workout.
BTW, my suggestion was without auto pilot and based on your initial post that it veered starboard

[SoWhat]

Engine tachs could be way off.
Buy a laser tach from Amazon. $20.
Check engine rpm's at fan belt. Check shaft rpm's just behind trans.
Once you are sure engines are synced, move into lazarette. Make sure both rudder shafts move equally when turned manually at helm.



https://www.amazon.com/AGPtek%C2%AE-...77771481&psc=1

[koliver]

On a new to you boat you can expect no accuracy in any of the systems identified in the posts above. Until you have checked them all, you can't know which one to adjust. Good luck with them all.

[mvweebles]

The autopilot can probably be recalibrated to zero, and do make sure the engines are pretty close to synched. But your description sounds like the boat physically veers, and its getting worse.

Have you checked the linkages that connect the two rudders together to make sure everything is tight? There should be a linkage bar with adjustment nuts to align the two rudders - check all fasteners and make sure the linkage points have no lateral play (there may be a little vertical play if there are bushings). Not always intuitive when boat is in water with actual rudders visible, but do the rudder shafts appear equally aligned? Any chance you can see the rudders while you stand behind the boat (swim platform)? Find a stretch where you can have someone drive the boat in a straight line while you watch how the rudders operate to assure they are working in unison.

No other symptoms such as excessive vibrations or list to one side? No recent grounding?

Peter

[RT Firefly]

Greetings,
Mr. r. Agree with Mr. k. You have no idea what the source of deviation is. Might be loose fittings, wonky rudder indicator, air in steering....any number of things.


Restart from square one checking and aligning each part of your steering system. Change only ONE thing at a time then test.


You should be able to synchronize your engines by ear. Can't remember the technical terms but out of sync engines will "beat" or "thrum". Do this at cruise speed. The closer to even, the slower the "thrum". Note tach' readings accordingly.

[North Baltic sea]

Hi,

do twins spin in the same direction or one right-handed and one left-handed?

The single always turns litke with the rudder in the 0° position, depending on which side the propeller is on.

Nbs

[mvweebles]

Originally Posted by North Baltic sea

Hi,

do twins spin in the same direction or one right-handed and one left-handed?

The single always turns litke with the rudder in the 0° position, depending on which side the propeller is on.

Nbs

Twins should counter-rotate. When viewed from astern and in forward gear, the right prop should spin right, the left prop should spin left. Although there are examples of counter-rotating engines, usually the engines are the same with the reverse direction changed at the transmission. Many years ago I encountered a boat where they both spun the same direction. I could only guess that the builder or re-builder had two of the same gears on the shelf and figured "what the hell, I'll just install two of the same."

Further, on twins, the rudders are almost always offset from prop-centerline to facilitate prop-shaft removal (and almost always offset to outboard of the prop centerline).

The part that has me puzzled - and why I suspect a loose linkage - is the OP states the problem has changed and worsened.

Peter

[Iggy]

Originally Posted by RT Firefly

Greetings,
Mr. r. Agree with Mr. k. You have no idea what the source of deviation is. Might be loose fittings, wonky rudder indicator, air in steering....any number of things.


Restart from square one checking and aligning each part of your steering system. Change only ONE thing at a time then test.


You should be able to synchronize your engines by ear. Can't remember the technical terms but out of sync engines will "beat" or "thrum". Do this at cruise speed. The closer to even, the slower the "thrum". Note tach' readings accordingly.

I would start at the basic stuff first. Are both rudders at the same position. Check each one of the tiller arms. Are they loose, is every thing tight? If all looks good, but out of position from each other. Than your rudders may need to be synchronized.

General speaking, there should be a valve between the two rudders. Turn the wheel all the way to Port. Open the valve and than close. You should hear a noise of the fluid moving. Than move the wheel to Starboard. Open and close the valve. Do this about 3 to 5 times.

It would not shock me that a tiller arm is loose. With time becoming looser and looser as you are describing.

[ryastu]

The part that has me puzzled - and why I suspect a loose linkage - is the OP states the problem has changed and worsened.
Peter

correct the problem has worsened over time….