Lowest consumption autopilots?

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Polly1

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What is the lowest consumption that anyone has had from an electronic autopilot?
The only windvane option for my 40 ft center cockpit yacht is an expensive hydrovane unit. I have an ST6000 with a hydraulic ram on the quadrant and a recent trip showed that to be excessive in terms of current. I also have a Navico Wheelpilot that I haven't tested much but promises lower current and I have my eyes on this

http://cptautopilot.com

which promises an average of 0.4A

Does anyone have experience of long passages on electronic autopilot and the current consumption?
I have 400W solar and a wind generator and would get 2 wheel pilots. I figure with 3 available I should be reasonably well covered against failure. I dont want to start a windvane vs electronic discussion, just want to know how these low current claims stand up.
 
Polly1 said:
What is the lowest consumption that anyone has had from an electronic autopilot?
The only windvane option for my 40 ft center cockpit yacht is an expensive hydrovane unit. I have an ST6000 with a hydraulic ram on the quadrant and a recent trip showed that to be excessive in terms of current. I also have a Navico Wheelpilot that I haven't tested much but promises lower current and I have my eyes on this

http://cptautopilot.com

which promises an average of 0.4A

Does anyone have experience of long passages on electronic autopilot and the current consumption?
I have 400W solar and a wind generator and would get 2 wheel pilots. I figure with 3 available I should be reasonably well covered against failure. I dont want to start a windvane vs electronic discussion, just want to know how these low current claims stand up.
Click to expand...

Try balancing sail trim. Also some courses are more demanding that others.
 
Polly1 said:
What is the lowest consumption that anyone has had from an electronic autopilot?
The only windvane option for my 40 ft center cockpit yacht is an expensive hydrovane unit. I have an ST6000 with a hydraulic ram on the quadrant and a recent trip showed that to be excessive in terms of current. I also have a Navico Wheelpilot that I haven't tested much but promises lower current and I have my eyes on this

http://cptautopilot.com

which promises an average of 0.4A

Does anyone have experience of long passages on electronic autopilot and the current consumption?
I have 400W solar and a wind generator and would get 2 wheel pilots. I figure with 3 available I should be reasonably well covered against failure. I dont want to start a windvane vs electronic discussion, just want to know how these low current claims stand up.
Click to expand...

There is definitely some difference between the systems and even brands. In general, a direct electric drive will be more energy efficient than hydraulic where energy efficiency comes second to reliability and brute force.
But the prime factor will be, how much rudder input your boat needs to keep on course. Some boats can maintain their course with a minimum help from the pilot, other need constant corrections even in calm conditions. Often setting of the sails or the parameters of the autopilot can make differences expressible in high multiplies. By the setting of the pilot parameters I mainly mean how accurately you want the pilot to stick to the course. The price in terms of power consumption for accuracy is high, so the idea is to set it only as high as it is really needed. Even when demanding no miracles and in perfectly calm conditions the claim of average 0.4 A for a boat of your size seems to be a wishful thinking of the manufacturer. In the real world, you definitely should be prepared for a bit more - but as I said before, you should concentrate more on experimenting with the settings of the pilot and sails than with the brand of the device.
 
Polly1 said:
What is the lowest consumption that anyone has had from an electronic autopilot?
I have an ST6000 with a hydraulic ram on the quadrant and a recent trip showed that to be excessive in terms of current. I also have a Navico Wheelpilot that I haven't tested much but promises lower current and I have my eyes on this
Click to expand...

Which ST6000? there are ancient and newer models, usually coupled to an electric linear drive. Which hydraulic pump and ram do you have? We've found our type 1 drive to be quite frugal with power if the sails are balanced (38ft boat) and it does 95% of our steering, including 3 Biscay trips. Our 200w solar and reasonable sized battery bank is more than adequate, the fridge is the problem. I binned the wheel pilots on 2 boats, too slow reacting, underpowered and belt slip can be a problem.
 
If you are seriously going long distance then invest in the Hydrovane and reserve the autopilot for use when motoring. As said consumption is a function of how much the autopilot has to work so balancing the boat to minimise that work is the way to keep consumption down.

The pilot you link to is a very simple motor type that has none of the features that are common on other pilots such as interfacing with your instruments so will not steer a course to the wind, only a compass course.. To achieve low consumption the same rules apply as with your existing pilot.

I should add that another wheel pilot would be a complete waste of money. You will probably find your Navico is also very limited as they simply do not have enough power, nor sensitive enough to control the boat reliably in anything other than light airs. If you do want 3 systems then your ST6000 is adequate for one, a Hydrovane or Wind pilot as your main device and a small tiller pilot to drive the vane when needed as a back up.
 
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Sandy said:
Do you have a wheel or tiller?
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The answer to that perhaps lies in the words "40 ft center cockpit yacht" and reference to "wheel pilots". (He's in Singapore so the American spelling is perhaps moot.)

Polly1: as well as the Hydrovane, a Windpilot Pacific Plus would almost certainly fit your boat. Not cheap, though.
 
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There also the compromise of a hybrid system, where an electronic autopilot doesn't operate the steering directly, but instead operates a servo blade in the water, which in turn operates the steering. This would, I think, result in a very significant saving in power

I believe some wind pilots (e.g. Cap Horn) are designed to facilitate such an arrangement. But once you've got that installed, why not use the wind vane itself, unless conditions are particularly tricky.
 
As well as sail balance, the consumption of an autpilot can be heavily influenced by
rudder design e.g. how much balance
software e.g. how intelligent is the pilot
settings e.g. is the gain set right, dead band, sea state...
 
LittleSister said:
There also the compromise of a hybrid system, where an electronic autopilot doesn't operate the steering directly, but instead operates a servo blade in the water, which in turn operates the steering. This would, I think, result in a very significant saving in power

I believe some wind pilots (e.g. Cap Horn) are designed to facilitate such an arrangement. But once you've got that installed, why not use the wind vane itself, unless conditions are particularly tricky.
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Most servo-pendulum systems can be used with a small tiller-pilot in lieu of the wind-vane. Windpilots (and perhaps others) come as standard with a hole machined for a tiller-pilot pin. The power saving compared to a conventional electric autopilot is immense: the tiller-pilot simply gives instructions to the servo oar. It does not apply any steering power. A tiller-pilot can also be used with a Hydrovane, but since there's no servo advantage, the electrical savings would perhaps be less. (I've used a servo-pendulum system in this way, but not a Hydrovane, so any alternative experiences are welcome).

Such a hybrid system offers the obvious and attractive possibility of mounting a conventional servo-pendulum on a centre-cockpit yacht, controlled from the cockpit by a remote tiler-pilot controller. I've never heard of a yacht being steered in this way, but perhaps someone else has?
 
The Jefa linear drive and direct drive are quite power efficient. Lots of information on their website. I have the linear drive, and it's good.
 
macd said:
The answer to that perhaps lies in the words "40 ft center cockpit yacht" and reference to "wheel pilots". (He's in Singapore so the American spelling is perhaps moot.)
Click to expand...
Thanks for pointing that out. Clearly I missed it in my skim read yesterday.

Put me right off having a center cockpit as it appears that you cannot use an emergency tiller.
 
Sandy said:
Thanks for pointing that out. Clearly I missed it in my skim read yesterday.

Put me right off having a center cockpit as it appears that you cannot use an emergency tiller.
Click to expand...

Yes, you can. However, some are in the aft cabin which requires a slave person to operate and others have an extended stock that goes up through either the aft cabin roof or the aft deck so the emergency tiller can be operated from outside.

It is a requirement of the RCD that an emergency tiller is provided - but does not say it has to be easy to use! However, first steering systems are generally reliable and second most (all?) centre cockpit boats are likely to have an autopilot that operates direct to the quadrant which is an effective alternative to the main steering system.
 
Tranona said:
Yes, you can. However, some are in the aft cabin which requires a slave person to operate and others have an extended stock that goes up through either the aft cabin roof or the aft deck so the emergency tiller can be operated from outside.
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Indeed. Our rudder has a fixed stock that passes up through the aft cabin (the visible part is polished stainless) and is supported by bearings at the bottom of the hull and at the aft cabin top - about the strongest arrangement you could have for a spade rudder. Because the point it emerges on deck is well aft of the cockpit, there's room for a reasonable length tiller to swing without fouling the binnacle - a common problem for emergency tiller designers. The handle end of it protrudes about 18 inches into the aft end of the cockpit which should be quite ergonomic for steering.

The stock in the cabin would be a bit of a passion-killer if it passed up through a centreline double berth, but our aft cabin is rather small with the bunks either side so that they can run forward under part of the cockpit seats and side decks, and the centreline pole is hardly noticeable.

Tranona said:
most (all?) centre cockpit boats are likely to have an autopilot that operates direct to the quadrant which is an effective alternative to the main steering system.
Click to expand...

Plenty (including ours when we bought her) seem to cheap out with a wheel drive, but replacing this with a proper linear drive was one of the early jobs I did. As you say, it makes an excellent backup to the main system; ours is cable and though I've renewed the wires and adjusted the tension etc, there's still a small possibility of it breaking or jamming one day. The autopilot can take over at the touch of a button, and if the situation did arise then I'd happily leave it to steer us all the way to port. I'd fit the emergency tiller fairly early on just in case, but probably not use it until final manoeuvering to a mooring or alongside.

Pete
 
Hope I never have to use mine. The wheel is close to the transom and only just in front of the rudder stock. The emergency tiller is designed to be used from aft which means dropping the transom platform and standing on that to steer. Would not want to do that in anything other than a flat calm. Fortunately the steering is rod and the autopilot is direct onto the shaft.
 
pvb said:
I thought it was high enough to clear the top of the aft platform, must have another look at mine.
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I read it as needing the platform down in order to have somewhere to stand to operate the reversed tiller, not because the platform fouls it.

Pete
 
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