Auto Pilot Question

Hi folks,

I recently took my new-to-me trawler out for a multi-day trip. On the way home I engaged the auto pilot for the first time, and the boat did a U-turn to the right at 8 knots. When I grabbed the helm, nothing happened, as it is a hydraulic steering system. After reducing speed, I disengaged the AP and hand-steered the rest of the way.

Is it normal to have NO steering control from the helm when the AP is engaged in a hydraulic system? My last few boats were sailboats with mechanical steering that could be overridden while the AP was engaged. I think that I probably could have adjusted the heading on the AP, and all would have been fine, but I wanted to ask. BTW, the AP worked fine on the sea-trial.

Thanks for any input and tips.

Cheers, Bill

It is normal for the AP to disengage the manual steering.

Also, you may want to give the AP a 2nd chance. I find that our AP takes a while to initialize and also sense the course (it is old enough to have a magnetic compass down in the bilge). When first engaged it often sends us off on its own course. After a reset to standby, 2nd try is usually stable. Also, we get a warning alarm when the AP looses course.

Absolutely normal, the wheel should just freely turn while AP is engaged. Sounds to me some time with the AP manuals and then some time in open waters playing is all you need.

Some (and most newer models) AP's have the capability to be over ridden by the helm of a hydraulic system, some don't. Always best to see what the AP is set to before engaging, for instance if set to go to a waypoint as some are integrated with the GPS/Plotter.

We have an ancient Wagner auto-pilot and I can manual steer with the A/P engaged.

As usual...it all depends....


My older Raymarine can be steered through...most of the Robertsons/Simrads I have used I can not. Then again...without checking...it could be the steering system type/combination more so than the AP.


I would be worried about the U-turn....on the pilots I am used to, you have to hit something twice to get the AP to go to a waypoint...so just hitting autopilot shouldn't result in much of a turn (small normal).


Sharp reactions that eventually are correct are usually a sign of too much rudder gain or response rate.

A U turn meaning it turned 180 degrees and straightened out?
Or did it go in circles?

A friend had an Autohelm (now Raymarine) that had a bug and would do circles if the dodge buttons were pressed in a certain sequence. (There was a fix that could be programmed into it that he did later that day)

An autopilot would turn 180 degrees if you commanded it to follow a "track" in the wrong direction. (easy to make that mistake)

Our wheel at the helm is free-spinning (aka useless) when the AP is engaged.


Our "rudder reference" went south once, and the symptom was similar. Our electronics guys replaced the "rudder reference", all good.


-Chris

Have had three hydraulic APs, manual steering for dodging
depended on gpm flow from the pump. If set too high it was not possible
to hand pump enough flow to over ride the AP pump, lower flow allowed
the helm pump to exceed the AP pump flow.
Had to turn helm continuously, like holding a dodge button, to over ride
the set course.

Ted

My SImrad will not allow me to hand steer when engaged. Check to see what your source of input is for the AP. You may have several choices on the display and if it was not set to "Compass" but instead got input from something else (like a GPS) it may have been only doing what it was told.

Thanks folks for all the great replies. As I mentioned, I am new to the whole hydraulic steering thing. I'm sure that it was pilot error, and will check things when I return to the boat.

Thanks again, Bill

Ok, I'll ask:
What brand and model AP?
What was the AP compass reading before engaging? Did that jive with your heading.

ranger42c said:

Our wheel at the helm is free-spinning (aka useless) when the AP is engaged.


Our "rudder reference" went south once, and the symptom was similar. Our electronics guys replaced the "rudder reference", all good.


-Chris

Click to expand...

bingo...check the rudder response sensor...I have found dozens that just fell off and caused similar random AP responses.

Have to say one of things I love is an AP remote on a nice long cord, and fortunately the PO of my old Robertson 300 equipped Hatt was of the same mind. Made it very easy to disengage the the AP instantly because I always had it in my lap or immediately at hand. Between the "auto" and power steering functions I used the helm wheel no more than 10% of the time, usually slouched back in the helm seat. Ann preferred using the helm wheel, so different strokes.

BTW, I could override that 300 with the helm; which I tested a few times but didn't really need. The best system for that I've seen is Garmin's Shadow Drive.

Does your a/p steer using a heading input from a compass/electronic compass? If so, it is a good idea to check the heading shown on the a/p screen and the heading on your compass to make sure they are the same. If they are not, you may have to do the turn-slowly-in-circles exercise to re-calibrate the electronic compass. A severe turn when 1st switched on happens to me when I forget to check that my a/p's heading input is correct.

An autopilot compass can be anywhere on heading....not even close to the ship's magnetic compass and will work fine. It may confuse you...but the AP just senses a change in magnetic lines to steer a straight course...it doesn't care which lines.


At least all the older style ones...maybe not the newest like the Garmin Shadow Drive which I have no experience with. But any that just use the old cheapo magnetic flux compasses. (like below)

Rudder feedback linkage or sender failure was my first guess.

APs that I've used stay on the compass heading sensed when Auto is pushed. You usually need to do something further to get the AP to chase a waypoint.

On my current Capilano hydraulic/Raymarine ST6001, I can temporarily overpower the hydraulic pump by spinning the wheel quickly. Not enough to dodge a boat but will dodge a crab pot float.

Had the same thing happen after I bought my boat and the first time I engaged the AP. Had to re-calibrate the flux gate compass.

I attribute it to metal added or removed in the vicinity of the compass during the change of ownership.

Has been fine now for years...

I had a very similar experience years ago with a Simrad AP. It turned out that it was a "serious short between the AP control panel and the helm seat." As was previously stated, the fix was to study the manual and spend time on the water practicing with the pilot.

Hi folks,

To answer the question about the brand, the AP pump is an Accu-steer, not sure about the about the AP unit itself. I did not look at the heading on the AP before engaging it, so I'm not sure about that either. Yes, I have a lot to learn. I'll be reading manuals and trying different things next time I take her out.

Thanks for all the input.

Cheers, Bill

When I installed my anchor windlass the power was routed too near the gyro compass and would lock the gyro when retrieving the anchor. It wouldn't affect it dropping the anchor but the extra power draw pulling it would lock the compass. I simply leave the electronics off or in standby until the anchor is bedded in the roller before turning it on and the problem is solved. Re-routing the power is not an option, nor is moving the gyro.

I had an issue with storing my 100 cubic foot scuba bottle as well, under the bunk forward affected the gyro compass, so now it lives under the footrest on the port side pilot house seat. Sometimes small boats make you adapt to "the way things are".

Had that happen when a metal framed chair was stored near the AP compass.