Why do auto-pilots fail on long trips??

[lateral]

Originally Posted by DumnMad

Right. Your 2nd pump idea is a goody.
We had 4m to 8m waves on the quarter, nicely rounded but each wave trying to push the boat off course. My boat has a big below-deck electro-hydraulic AP so should have been able to cope but apparently the AP's constant starting at lower than ideal voltage resulted high amps overheating the coils.

If you are already shy on battery voltage that is going to make it worse, surely.
These are inductive loads, volts down current up. More heat.
More batteries, more charging capability, two pumps an an accumulator?

[DumnMad]

Originally Posted by lateral

If you are already shy on battery voltage that is going to make it worse, surely.
These are inductive loads, volts down current up. More heat.
More batteries, more charging capability, two pumps an an accumulator?

Yep. The boat came with the batts in 2 banks. Should have been just one big bank and the bigger the better.

[Exile]

Originally Posted by billknny

No, you have it backwards.

Reducing the response of the AP to course error will reduce power consumption and wear, and in some conditions actually improve course-keeping.

Many times when the boat surges as a wave goes under it from behind, when the wave passes the boat comes back on (or close to) the original course. A quickly responding AP will correct the original turn, and then need to un-correct to get back, with most of that back and forth being wasted energy.

In general:
1.) If the steering system is shifting more or less regularly from left to right, reduce the "response".
2.) If the boat is wondering far off course before correction is applied, increase response.

Think about how you steer manually. There are times (especially downwind) when you just need to hold the wheel still and let the boat go, and then come back. An AP doesn't KNOW what will happen next, so if it responds quickly in those conditions, it is working too hard and not doing as good a job.

What you're describing seems to be resolved using the settings on the damping function on my AP. This is somewhat different from the 3 settings my AP also has for Normal, Downwind & Economy.

[UNCIVILIZED]

Originally Posted by billknny

Think about how you steer manually. There are times (especially downwind) when you just need to hold the wheel still and let the boat go, and then come back. An AP doesn't KNOW what will happen next, so if it responds quickly in those conditions, it is working too hard and not doing as good a job.

Actually there are a pretty good number of AP's that know what will happen next, particularly ones with good CPU's, coupled with a decent instrument package. The mid & upper tier ones actually steer better than humans do in all but the wildest situations. Meaning racers who have 3x too much sail up in transoceanic or RTW races.

For wheel mounted pilots there are compounds available with which to dress the belt which will both reduce slippage when it's steering, & belt wear.

[daletournier]

Originally Posted by Paul Elliott

My boat has a below-deck electro-hydraulic AP, and a big barn-door rudder. I also have a Monitor windvane. I can trim the sails for neutral helm and in easy seas the AP just loafs along. But in big seas, especially when they are coming on the quarter, whenever a swell hits us gravity tries to force the stern downhill and the unbalanced rudder requires a lot of force to keep us going straight. We've got an average-size wheel, and sometimes it takes two hands and a foot to keep us on course.

In these conditions the AP has to work much harder. We need to increase the AP sensitivity / response speed to avoid being pushed sideways. I've had the AP hydraulic pump fail, but that was due to salt water damage. There was rudder-post seepage and the limber hole that drains that little compartment had become plugged. The AP is mounted in that compartment.

Anyway, my point is that while sail trim is very desirable, there are other factors that may affect the strain on the AP. Rudder design is one of these, and of course sea-state.

Yes, big quartering seas change everything which is compounded by surfing.

[mikedefieslife]

Originally Posted by Rorzech

I don't know why most sailors avoid the simplest of AP's . The best one that works excellent is just a sheet to your jib or genoa , run it back and around to the other side of the cockpit , then to the tiller which has a shock cord attached on the other side of the tiller providing the needed tension. The wind in your jib will steer your boat through anything. Try it out and give you electric AP a break and it will last longer. There's lots of youtube videos on this subject.

Most cruisers won't have a boat with a tiller. They tend to disappear in boats over a certain size, and are few an far between on catamarans.

Also what happens when a wave or swell moves your boat 30 degrees off course?

[UNCIVILIZED]

Originally Posted by mikedefieslife

Most cruisers won't have a boat with a tiller. They tend to disappear in boats over a certain size, and are few an far between on catamarans.

Also what happens when a wave or swell moves your boat 30 degrees off course?

Depending on where the rudder post is in relation to the wheel, or if you're willing to move the wheel, it's possible to mount a tiller who's primary purpose is to be linked up to the AP or vane. And it can be lifted up, or fully removed, when in port, in order to regain the space in the cockpit.

Honestly, most helms are quite poorly placed, as they position the helmsman where he/she has zero protection from the dodger & weather cloths. And often times makes it difficult to see the telltales/sail trim while driving.