when autopilot doesn't like the conditions

[Nikki S]

Hi,
the other day we hit some weather that was rougher than anticipated. My husband hand steered for 6 hours as we tacked into port as he said the autopilot was not coping with the waves, which were short and steep and breaking on top of the bimini, bent some stanchions because we had surfboards tied to them, twice knocked us so the mast was almost horizontal and touching the neighbouring waves.

Some folks said that when they get such rough conditions they sit inside on the top step and watch (i.e. let the autopilot do most of the steering and just jump up to the wheel here and there if need be), and I was later reading that modern autopilots (ours is 15 years old and does a great job) tend to steer in heavy weather better than a human.

I'm curious as to whether autopilots newer than ours would cope in those seas.

Even if we had one which could, sitting on the top step would have been near impossible, and anyway the companion way hatch was closed after the first time the dodger failed to keep a waterfall off the steps.

Please tell me about the limits of your autopilots.

[DeepFrz]

It depends on the auto pilot strength and mounting strength whether or not they can handle extreme conditions. I lean towards the side that says oversize/over engineer the auto pilot system so that it will be able to handle extreme conditions. There is another very recent thread on auto pilot drive mounting with pictures from several boats.

http://www.cruisersforum.com/forums/...se-191413.html

[Oceanride007]

Yes well, my AP brain failed recently and I had to have a good look, I found that my actuator was undersized slightly.
As I single hand and likely to go to remote places, something had to be done. Choice was to upgrade everything or carry spares.

As my undersised actuator was still doing its job and a current model, I decided to take the risk but upgrade the Electronics only. Logic here is that for time being, am coastal sailing and stronger actuator has same footprint upgrade later and I'd like to get more use out of existing for now.

Mind you electronics AP tend to be more suited to little wind, Windvanes are more suitable for strong winds.

Anyway, the new electronics work so much better, I now regularly sail to App wind, wonderful, sails better than I do.

[sailorboy1]

I find in bad conditions it is better to run the ap at a lower response setting so it does not try to fight the conditions as hard (still holds a lot better course when being knocked around than I can). I also have found that in bad conditions it is better to run on a course setting and not in track mode as the ap gets real active trying to stay on the line.

[Nikki S]

Thanks Deep Frz, Oceanride007 and Sailorboy1,
are there any sea states such as short, steep waves that cause your autopilots to be unable to hold course?

[Oceanride007]

Sorry, I'm in pretty protective waters provided by the GBR, haven't even needed to take it out of leisure mode yet. Its only a month old, but I did sail back to Melbourne from Hobart, diff yacht but similar AP, I just loved the way how the modern AP anticipated ie wave on the bow tilts the yacht, it already started its corrective action before it went of course. Thanks for the the thanks, first one this year.

[sailorboy1]

Originally Posted by Nikki S

Thanks Deep Frz, Oceanride007 and Sailorboy1,
are there any sea states such as short, steep waves that cause your autopilots to be unable to hold course?

Mine will hold course even if it is hard on the boat steering. Visually it may not look like it is holding the course, but if I watch the COG it is overall. Because the steering takes a lot of stress during this I turn the response down in bad condition, which means the ap holds a looser course.

[Alberg30Shill]

Consider periodically turning off the autopilot, hand steering to check for excess weather helm, trimming the sails and turning it back on again. If you can provide it with wind data and are well off shore, windvane mode could be a good choice. If you have the boat units, a windvane can't be beat :-)

[Falbala60]

Originally Posted by sailorboy1

I find in bad conditions it is better to run the ap at a lower response setting so it does not try to fight the conditions as hard (still holds a lot better course when being knocked around than I can). I also have found that in bad conditions it is better to run on a course setting and not in track mode as the ap gets real active trying to stay on the line.

EXACTLY ! I experient the same 10 years ago in Greece. On a leg from Hydra to Milos in a "calm Meltemi" force 7-8, beam-reach, waves 4-6m, the AP was unable to steer. Tried "human" ... worse.

Even if she was a charter, I decided to "play" with the AP settings... the first time I did that.

Lowering the response SOLVED the problem and we did 6 hours nearly sleeping in the cockpit ...

SailorBoy is RIGHT !!!

[billknny]

Originally Posted by Nikki S

Hi,
the other day we hit some weather that was rougher than anticipated. My husband hand steered for 6 hours as we tacked into port as he said the autopilot was not coping with the waves, which were short and steep and breaking on top of the bimini, bent some stanchions because we had surfboards tied to them, twice knocked us so the mast was almost horizontal and touching the neighbouring waves.

Before anyone can really answer your question we really need to understand what it means when you say your AP was "not coping" with the waves.

Could it not move the rudder against the forces generated as the computer commanded? If so then, your drive is under-powered.

Was it just not able to hold course with rapid and erratic changes? Then you need to learn how to tune it. I can assure you that the same tuning parameters that work well in clam water upwind will be totally inappropriate to rough seas downwind.

Finally, was hand steering able to "cope with" the conditions? If not, maybe its the boat?

[deblen]

Think about this:
An A/P cannot tell the rudder drive to turn until the A/P brain has detected that the vessel HAS changed course. In other words,the vessel is already moving in an off course direction BEFORE A/P commands any rudder action to counteract this off course movement & momentum.

A wide awake experienced helmsman can see with his/her eyes & feel with their body an oncoming sea. An experienced helmsman will automatically start turning the rudder to counteract what they know the vessel is going to do when that wave hits.

The more difficult the conditions,the more important it is to counteract with rudder sooner.

IMHO-no A/P can steer as well as a sharp helmsman in difficult conditions over SHORT time periods.

However,a well adjusted & proper functioning A/P can steer a better AVERAGE course over long hours.

To test your A/P's performance,during difficult conditions,turn it off. Steer by hand WITHOUT turning the rudder. Note how many compass degrees that the vessel "wallows" over. Then,try to manually steer a better course,again noting the compass degrees that the vessel wanders.
Your A/P cannot do any better than somewhere in between the two results & that is assuming all components are tight & up to snuff.

Adjust (loosen) the yaw(tight course) adjustment to allow the A/P to wander the amount of P & S degrees (determined above) before it applies opposite rudder. Widen the XTE if you must use it. This will greatly ease wear on your A/P drive,steering system & current draw.

With regards the OP's description of conditions-seas breaking astern,green water on bimini,knockdown conditions,etc. Your rudder(s) must have been out of water or useless in those conditions.
If so,IMHO,with respect,it may have been past time to turn A/P off & steer manually. Ships have been known to broach in those conditions,especially when on A/P.

Len

[Tessellate]

Waves breaking over the bimini? And near knockdowns? That's sounds like pretty serious waves. Where was this, and were there currents interacting to create the short steep waves?

I think any autopilot could have difficulty with those kind of conditions. Sounds like you were going upwind, given you say you were tacking?

I don't think it's a matter of old vs modern autopilot. It depends on a lot of factors - what autopilot you have, whether the boat was overpowered from having too much sail up, etc.

[hamburking]

Originally Posted by sailorboy1

I find in bad conditions it is better to run the ap at a lower response setting so it does not try to fight the conditions.

AGREE!!

I used an autohelm 1000 tillerpilot on my C&C25. In rough weather and BIG waves, it did an outstanding job of steering...much better than I could have done. The weird thing is that it hardly moved the tiller at all. And yet, we always stayed on course.

Aside from the autopilot, there are other variables to steering...sail trim, location of windage, weight distribution, underwater shape, all sorts of things. I kept my boat light and the decks clear...and had no trouble.

When i crossed the Atlantic on a Swan 48, the AP steered the whole way with no trouble. Except when the skipper was angry, he would tell me to steer by hand...to "give the ap a break". The joke was on him though...I love steering a fine yacht on the open ocean!!!

[Pizzazz]

I believe the autopilot can steer better than me 99% of the time. There is a learning curve though for you and for the autopilot. I would go through the following steps:

Make sure you have accurate heading info into the autopilot. A 10 Hz compass helps. Add a rudder sensor. Feed it wind data. Set the auto learn option to on (the autopilot learns to pre-steer in big waves, similar to what an experienced helmsman does.Balance the sails, learn how to use the settings.

[donradcliffe]

If its rough and you are getting knocked down, its past time to reef. Autopilots have an easier time sailing to weather than reaching or running.