Autopilot failure on long passage

[RaymondR]

I am going to try taking the two sides of the existing outputs, normally +/- five amps through resistors so that they are reduced to about an amp with taps in the upstream sides to provide the gate voltages for a H bridge consisting of a bunch of complementary MOSFETS.

[goboatingnow]

Yeah relays or mosfet drives would allow greater current.

[mako]

@ak5609, what advice exactly are you looking for? So you're on a cat, you're single handing and then the autopilot fails. If you don't have parts to repair it, and no backup unit, what do you think you can do?

Does your cat balance well so it can keep a relative straight heading (assuming not too heavy seas)? Does it lie ahull well? You can hand steer for hours but eventually you need to rest. So if none of the above are doable, then did you bring a parachute to lie to, then get a solid 8hrs of nappy nap so you can go on for another day?

[teneicm]

Singlehanded, or even double handed continuous steering can be exhausting, especially if the sea state gets up. I wouldn't go trans-oceanic without a fully redundant autopilot unless I had a large-ish crew that would require no more than 2-3 hours of hand steering at a go. Especially on a cat where there's plenty of room to put in a back-up system.



We went around the world with a primary system that was fully networked with the chartplotter, and a backup which was the older autopilot which would only hold a compass course. We never had to resort to the backup (but we did cannibalize a rudder reference transducer from the old system when the primary's quit). But we had enough friends and heard stories of people that had to hand steer on long passages after AP failures, that we were never unhappy with our choice to have a backup.

[merrydolphin]

I carry THREE auto pilots. A robust below decks pilot, a CPT wheel pilot and a RayMarine wheel pilot. Move than once I was down to one! Self steering a critical factor, especially with a crew of just one or two.
Another great way to go is a good autopilot AND a good vane gear. I think this is best. I had a Monitor vane gear but the friction loads were just too much for it on my Kelly Peterson 44 center cockpit boat. Long complex cable runs in both directions. I would have been better off with something like a hydrovane. But I already had the Monitor from another boat. So in the end just decided to get yet another back up wheel pilot. The Ray Marine did a marginal job on the KP 44. The CPT was OK. And the old below decks rotary pilot was great. Again, if I had it to do over I would have just sprung for the Hydrovane, or something similar.

[CarinaPDX]

The first thing is to know what you have. Anything in the cockpit (i.e. wheel or tiller pilot) is not going to be very reliable. You will need to plan for redundancy and/or repair parts, without a doubt. If it is below decks, probably driving the quadrant, then it is likely to be quite reliable. Still, it makes sense to consider what you could do if there were a failure.

If you have a wheel drive then I would take it off and stow it as an emergency alternative, then install a quality below-decks unit. This gives full redundancy plus a very strong and reliable autopilot.

On my second Atlantic crossing, westbound, I was sailing with a wind vane, which IMHO is the best autopilot for passagemaking. But nothing is perfect. In a squall with confused seas out in the middle of the Atlantic the wind vane turned the trim tab too far and it snapped off (so much for DIY solutions). Unfortunately I also used that trim tab for the tiller drive to reduce loads on the drive, so I was reduced to direct driving the tiller. I had been using a 4000+ and later an SP-5, all with the same top-end tiller drive [edit: the GP model], and had repeated problems that resulted in buying replacement motors and entire drives. Good thing. On that crossing I repeatedly had drive failures and was frequently rebuilding them while the sole working one steered the boat. Because I had lots of parts and experience I never had to hand steer for any length of time, which was good because it was pretty rotten weather the whole trip. Upon arrival I had the one working drive and the rest was junked. I expect to be buying a far more powerful drive in the future. Unfortunately I see no alternative to a cockpit drive for my 31' boat. Still, on passage the wind vane is my go-to solution.

Greg

[wingssail]

You need a good spare autopilot, but once you get it you probably won't need it. Gear is good now.

While circumnavigating everyone we met had autopilot failures and wound up hand steering. It never sounded like fun.

I learned from that to carry a spare.

Ourselves, we used a Monitor windvane 99% of the time and to steer our boat in windy conditions it worked hard; we had some breakage but kept it going.

For autopilot (which we needed for those windless days) we had Autohelm (Ray Marine) ST4000GP tiller unit and we made sure we had a spare drive unit.

But we never had a failure at sea. Go figure. Despite that we'll always carry a spare.

[JPA Cate]

Besides carrying spares, you may have to adjust your watch schedules. If there are two or more of you, you just gird your loins, and hand steer, or return to land where you can get what you need to fix it. This is also an indicator of what may fail in the future, so duplicate those bits. We've only had to hand steer on passage once, from the Tuamotus to Tahiti. We were younger, of course, but it is not an emergency situation, and you can just drift to sleep where you cannot trim the boat to go on, unsteered. As it happened, we were accustomed to 6 hr. watches, and we managed those, hand steering. Got our full sleeps in, too, Sure we got tired, but at the bottom line, it was doable for the days we needed to do it.

Now, our bodies have done well with that watch schedule, but we know people who do just 2 on 2 off, and I don't know how they get enough deep sleep to carry on, but maybe their bodies just cooperate. And we know people who have no watch schedule: whichever one of them wants to be on, goes on for as long as they want to do it, and it has worked for two circumnavigations and 30+ years! It just may be that one makes the commitment to do what's necessary, and make your body do it--whatever it is that needs to be done. We have marvelous capabilities as humans.

Ann

[geoleo]

Originally Posted by ak5609

Hello folks,

just had a discussion with a friend about the importance of our autopilot on our catamaran, and the question occurred, what to do on a transatlantic trip, singlehanded, when the autopilot stops working.

Perhaps grasp the steering wheel asap.

[RaymondR]

I tend to the opinion that a hydraulic linear drive with it's own tiller mounted on the rudder stock is the most durable.

I just replaced the electronics on mine and went for one with a 30 amp drive capacity drive computer and retained the old Simrad hydraulic linear drive considering it still superior to what else is available even though it's about 25 years old.

[goboatingnow]

Originally Posted by RaymondR

I tend to the opinion that a hydraulic linear drive with it's own tiller mounted on the rudder stock is the most durable.

I just replaced the electronics on mine and went for one with a 30 amp drive capacity drive computer and retained the old Simrad hydraulic linear drive considering it still superior to what else is available even though it's about 25 years old.

My own view is a modern rate gyro AP outperforms any windvane and is today more reliable as well. The whole reason for wind vanes was power consumption solar has removed this completely.

Hydraulic APs are very very difficult to repair if something gore wrong. Electric linear arms are easy to repair and have proven extremely reliable or easy to service . To repair a hydraulic AP in Las Palmas I had to fly the whole gear to a specialist in Holland as no one locally could touch it. Yet a electric linear drive would ( and was ) easy to repair.

I won’t have hydraulic system in a boat as a result. Electric is more Reliable and far easier to repair.

[RaymondR]

Originally Posted by goboatingnow

My own view is a modern rate gyro AP outperforms any windvane and is today more reliable as well. The whole reason for wind vanes was power consumption solar has removed this completely.

Hydraulic APs are very very difficult to repair if something gore wrong. Electric linear arms are easy to repair and have proven extremely reliable or easy to service . To repair a hydraulic AP in Las Palmas I had to fly the whole gear to a specialist in Holland as no one locally could touch it. Yet a electric linear drive would ( and was ) easy to repair.

I won’t have hydraulic system in a boat as a result. Electric is more Reliable and far easier to repair.

Skills deficiency problem.

Provided the hydraulic oil is not contaminated, the most probable problems with hydraulics is generally related to seal failures. Since these are highly standardized, very cheap and widely available a plentiful spares complement can be maintained and the tool kit usually found on any well equipped vessel is sufficient to carry out any repairs.

In contrast mechanical linear drives generally contain proprietary gear boxes and circulating ball screw drives which require manufacturer specific parts.

The electric and electronic parts are common to both systems so neither has the advantage there although those I have observed on hydraulic drives tend to be larger and more industrial.

[Chotu]

Originally Posted by RaymondR

Skills deficiency problem.

Provided the hydraulic oil is not contaminated, the most probable problems with hydraulics is generally related to seal failures. Since these are highly standardized, very cheap and widely available a plentiful spares complement can be maintained and the tool kit usually found on any well equipped vessel is sufficient to carry out any repairs.

In contrast mechanical linear drives generally contain proprietary gear boxes and circulating ball screw drives which require manufacturer specific parts.

The electric and electronic parts are common to both systems so neither has the advantage there although those I have observed on hydraulic drives tend to be larger and more industrial.

I definitely agree with this. That’s why I went with hydraulic myself.

It’s as simple as switching out a pump, or even switching out the motor on the pump because those are made to be removable.

Then you are back in business.

If it’s an electronics failure inside the rest of the equipment, you are up the same creek no matter what final Drive unit you chose.

This thread, however, is making me think twice about redundancy. I was about to sell my old wheel pilot and associated small course computer.

Maybe it would be best to hang onto that in case of emergency. Very easy to plug and play. I still have the stupid hole in my home waiting for the drive motor anyway. It would take about 15 minutes to switch from one type of auto helm to the other in an emergency.

So I guess I’ll keep it.

Because I have yet to get my hydraulic auto pilot working, because the pump doesn’t seem to be doing anything, I may just have to switch over to that wheel pilot for my little trip to the Rigger’s.

[hpeer]

Originally Posted by Baby tug

I used a Ray Marine tiller pilot to run a wheel pilot , it worked fine how many amps will it handle , I don’t think it’ll handle enough amps to run a reversing pump , I thought about using Relays , somebody might know how to wire that , I think it would work pretty good

You could use a PYPILOT or perhaps a Pelagic setup without the ram.

I use a PYPILOT to drive a CPT wheel.

[hpeer]

Out boat has both wheel steering and a tiller. The tiller is so the center cockpit can be steered by an Aries. I have 3 steering options, all failed at midnight on an overnighter.

Wheel pilot control head failed.
The tiller pilot drives the Aries but the tiller to rudder stock connection failed.
That also took out the Aries.

The tiller simply fell off. The failure was a 37 year old welded connection between a SS piece and a mild steel sleeve. That has been replaced.

The control head was a simple 12 vdc to 5 vdc converter.

Thankfully we had only 14 hours left, light winds, motoring downwind. Still a PITA.