when autopilot doesn't like the conditions

[daletournier]

Originally Posted by 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.

This is very true. Ddw or on the quarter with a big swell running is very hard on a auto pilot. I need mine on the highest response level when running in big seas and surfing. Upwind or on the beam you can help the autopilot by trimming the sails well, not so easy in big following seas.

[Nikki S]

Originally Posted by 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.

Yes, 4knt current interacting to create short steep waves - NSW coast, heading south, the 40kt southerly hit between Woolgoolga & Coffs Harbour off the back of a nasty low that crossed the Tasman a few days prior. We should have known better but like the forecasts only expected 20kts a couple of hours later. We were not overpowered- had tiny bit of main out and probably should have had a tiny piece of jib out. Turned motor on to aid with sustaining momentum after falling off back of waves. The human coped very well as he was able to see and steer for the confused sea state, and steer around bigger waves. He said we would have certainly been knocked down had we left it to autopilot because autopilot has no eyes. If that is the case, I'm glad it was morning and not pitch black...

[SaltyMetals]

V Interesting. I have always raised the Response level in stronger winds & waves so I find it counter-intuitive to lower it but i can see the logic. My AP is Raymarine ST6001+ 2004 but i do not find that it learns to pre-steer in heavy conditions so i switch it off and hand steer. Particulaly with a following wind & sea since it is important to anticipate the monster waves coming up from behind.
Andrew
"Genial Bee"

[thomm225]

Originally Posted by 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.

I was running downwind a few year ago and the winds piped up to around 30mph, the autopilot couldn't keep up so I took over the steering for the next four hours.

If I had not have taken control the wind and waves would have pushed the boat around beam too and it wouldn't have been pretty. I did have too much mainsail up though.

My autopilot is an electric powered one. Many on here said that if I'd had a windvane autopilot there wouldn't have been a problem running off downwind in 30 mph winds

Also the waves were very closely spaced and steep because I was on the far and very shallow side of the Chesapeake Bay where it's about 25-30 miles wide

[james247]

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?

I have to say the latest generations of autopilots have far more adjustment capacity. tuning than older versions they can be set to consider sea conditions
A gyro device usually electronic feels the pitch and yaw faster than my but. It compensates for it.
Go up a size in drive if you have a 35 footer get the drive for a 45 footer. Burns more energy but handles rough conditions. It is generally more robust.

[Cheechako]

I'm not sure there are AP's that will do well in the conditions you describe, that being breaking waves over the bimini and knockdowns. Basically the boat doesn't steer well period in those conditions, and you cant expect the AP to do better. Most often the boat in those conditions is stopping and restarting, so when slow or stopped there is no steerage at all.
My suggestion it get the boat moving better by heading off, changing sail trim etc so the waves are not effecting it so much.

[Squanderbucks]

Depending on the type of autopilot installed - hydraulic vs mechanical - most hydraulic systems that I have seen do not move the helms whether it be tiller or wheel when the autopilot turns the rudder. I had an old electromechanical one that did because it worked via a chain and sprocket attached to the wheel shaft. The entire steering system was mechanical with cables and pulleys. Boat was manufactured back in 1965 and not upgraded to hydraulic until 1995 or so. The wheel did turn on that old system but does not move on the hydraulic one.
As the autopilot does it's thing it will appear that nothing is going on unless you look out the stern and see how the boat's wake is tracking.

[Foolish]

It's not the rated strength or "over time" of the autopilot that matters. But sail trim, sail trim, sail trim. I believe that you were beating into the wind during the adventure. Heading off by a few degrees and easing the sails might have helped.

When using an autopilot it is very easy to trim the sails too tight and let auto work extra hard. As someone mentioned above, every once in a while you should take the helm yourself and make sure that the tiller requires no more strength than a 2 year old could muster. If it's any harder than that you should shorten sail or ease the sheets. Any time a wave slaps the hull and the boat points up, the sails will lose the wind and the boat will fall off again.

[Tessellate]

Originally Posted by Foolish

It's not the rated strength or "over time" of the autopilot that matters. But sail trim, sail trim, sail trim. I believe that you were beating into the wind during the adventure. Heading off by a few degrees and easing the sails might have helped.

When using an autopilot it is very easy to trim the sails too tight and let auto work extra hard. As someone mentioned above, every once in a while you should take the helm yourself and make sure that the tiller requires no more strength than a 2 year old could muster. If it's any harder than that you should shorten sail or ease the sheets. Any time a wave slaps the hull and the boat points up, the sails will lose the wind and the boat will fall off again.

We often hear this advice given but I'm sorry I just don't buy it. Strength of the autopilot *does* matter. For example I have an undersized wheel pilot on my boat - it simply doesn't have the rated strength for certain conditions, particularly closed-spaced following waves. No amount of sail trim will enable it to do its job. The waves are what are pushing the boat. It depends on the boat design too - a full keeler might track like a train running downwind but a fin keel boat doesn't.

Also the advice that the tiller should be finger light and require no more strength than a 2 year old could muster. They were in high winds with huge close spaced waves from high current interactions. I don't see how you could have finger-light 2-year-old steering in those conditions, even going upwind. The advice to crack off (fall off) a few degrees is good though, as that might have dealt with the waves better. But an underpowered autopilot could still have difficulty even after that.

[sailorboy1]

Strength (power) matters or there wouldn't be different size units for different size boats.

But of course conditions play into the the needed power. So sail trim, wind conditions, and wave strength, size and direction all are part of the whole thing.

But unless the autopilot is blowing fuses or tripping it's breaker it isn't a power problem if it can't steer the boat.

[Jim Cate]

Originally Posted by Tessellate

We often hear this advice given but I'm sorry I just don't buy it. Strength of the autopilot *does* matter. For example I have an undersized wheel pilot on my boat - it simply doesn't have the rated strength for certain conditions, particularly closed-spaced following waves. No amount of sail trim will enable it to do its job. The waves are what are pushing the boat. It depends on the boat design too - a full keeler might track like a train running downwind but a fin keel boat doesn't.

Also the advice that the tiller should be finger light and require no more strength than a 2 year old could muster. They were in high winds with huge close spaced waves from high current interactions. I don't see how you could have finger-light 2-year-old steering in those conditions, even going upwind. The advice to crack off (fall off) a few degrees is good though, as that might have dealt with the waves better. But an underpowered autopilot could still have difficulty even after that.

Perhaps the explanation is that Foolish seems to sail an Olsen 30... a very light mini-sled type boat, and for such boats the scaling factor permits very light helm loads.

For larger, heavier and (sorry folks) poorly designed boats, helm loads do get vastly larger, and auto pilots and helmsmen must work harder. On some points of sail, trim is very important, on other (downwind) courses the amount of sail, and it's disposition fore and aft is more important. All these factors get jumbled together for the poor a/p, and he is left to deal with the results. Being really brawny sure helps the machine cope!

Jim

[donradcliffe]

When the waves are breaking over the bimini is exactly the conditions I where I really want the autopilot to steer the boat, and I paid extra for a bigger, faster, stronger autopilot to do that. However, even the oversized autopilot (and the wife) will be a lot happier if you keep the heel angle down and reduce weather helm.

Just as an example, I was close reaching from the Maldives to Oman when the wind piped up to 30+ knots. All was fine until the Simrad hydraulic drive pilot got wet and died, so I had to switch to the backup CPT II wheelpilot. I dropped the main completely and furled the genoa down to about 80%. With the reduced heel and neutral helm the CPT was able to handle the last 36 hours of the trip--without reducing sail I would have certainly broken the shear pins on the drive.

[Pelagic]

Originally Posted by Nikki S

Yes, 4knt current interacting to create short steep waves - NSW coast, heading south, the 40kt southerly hit between Woolgoolga & Coffs Harbour off the back of a nasty low that crossed the Tasman a few days prior. We should have known better but like the forecasts only expected 20kts a couple of hours later. We were not overpowered- had tiny bit of main out and probably should have had a tiny piece of jib out. Turned motor on to aid with sustaining momentum after falling off back of waves. The human coped very well as he was able to see and steer for the confused sea state, and steer around bigger waves. He said we would have certainly been knocked down had we left it to autopilot because autopilot has no eyes. If that is the case, I'm glad it was morning and not pitch black...

Those conditions of heading into a 'Southerly' with wind against current are pretty extreme and you would be getting knocked around quite a bit.

Your husband made the right call of taking it a "wave at a time", which the AP cannot anticipate.

Also in those conditions where you are trying to power into steep messy seas, the heading sensor is also all over the place, confusing the AP even more.
Best to turn it off and simply steer for comfort.

[Pelagic]

Just curious
I have only transited that area non stop from Brisbane to Sydney.
In a southerly blow, is there no points that you can tuck behind enroute to wait out the easing of wind?

[Jim Cate]

Originally Posted by Pelagic

Just curious
I have only transited that area non stop from Brisbane to Sydney.
In a southerly blow, is there no points that you can tuck behind enroute to wait out the easing of wind?

There are quite a few of such. A few of the best are Cape Byron, Coffs harbour, Smokey cape, Sugarloaf Bay, Hat Head, Korogoro, and Port Stephens. some others that ain't so goo, and likely some that I've failed to mention. Alan Lucas's guides do a good job of describing them. All of those are pretty much all weather entry... the river mouth/bar entries are harder in stiff weather, many are impossible... and you can get trapped inside and not be able to leave due to residual swell on the bar, even though the wind has abated.

Jim