Electronic Autohelm or Self Steering Wind Vane?

[kev_rm]

I am curious about the concern about energy use for electric autopilots?

I believe mine averages (over time, not instantaneous) less than an amp in calm conditions and ~3A when its busy.

24hrs x ~3A x 12.5V = 900 Wh per day.

which is running my 100A alternator about 45 minutes a day, so on a month long crossing that would use about 6 gallons of diesel on my boat.

help me understand the energy use problem?

(I understand the efficiency of charging, etc, so what, its 10 gallons..)

[Dan Best]

>> 24hrs x ~3A x 12.5V = 900 Wh per day which is running my 100A alternator about 45 minutes a day

Unfortunately, unless you've got lithium batteries, your 100A alternater doesn't charge at anywhere near 100A unless your batteries are seriously depleted.

The acceptance rate of lead acid batteries decreases asymptotically to zero as the battery charges. I don't have the exact numbers in front of me, but basically this means that as your battery becomes more and more charged, it will accept less and less current. So if you start with a 50% depleted battery, it will accept a high charging current. This will gradually reduce as the battery becomes more and more charged. The last 20% and especially the last 10% may take many times longer that the first 20% or 10%. The actual acceptance rate is a function of the size of your battery bank, the kind of batteries and their state of charge.

[Matt Johnson]

Never been an issue with me. We typically keep topped up with 500w of solar and wind gen even with fridge, chartplotter, vhf, AIS, autopilot and everything else running on passage (10-30 days). Only a few times have we had to run the engine for power, but those times the absence of the autopilot draw wouldn't have prevent that need either.

Matt

Originally Posted by kev_rm

I am curious about the concern about energy use for electric autopilots?

I believe mine averages (over time, not instantaneous) less than an amp in calm conditions and ~3A when its busy.

24hrs x ~3A x 12.5V = 900 Wh per day.

which is running my 100A alternator about 45 minutes a day, so on a month long crossing that would use about 6 gallons of diesel on my boat.

help me understand the energy use problem?

(I understand the efficiency of charging, etc, so what, its 10 gallons..)

[AuroraGH]

Originally Posted by MJH

The easy answer is windvane for offshore, autopilot for everything else.

~ ~ _/) ~ ~ MJH

I would change that to windvane for sailing, autopilot for motoring.

I LOVE my monitor and use it even on day sails around the bay.

Autopilots burn power. I don't mind if I'm already running the engine but if I'm not I'd rather not use it.

[KP44]

Originally Posted by funjohnson

Anyone that thinks a windvane never fails, hasn't spent much time in areas where cruisers end passages.

Well rebutted. But Monitor Windvanes are well-known for being well-found and dependable. Many never fail whereas electronic systems must have a back-up readily available.

[Orion Jim]

I've singlehanded from New England to Bermuda four times. That totals something in excess of six thousand miles offshore. I have a Monitor windvane which has been fantastic in everything from a full gale in the Gulfstream to catspaws.
When the wind fades I have a Raymarine EV 100 wheel pilot which is linked to my Garmin chartplotter.
This combination has worked very well for me and has proven quite robust in my application.

[kev_rm]

This has **NOTHING** to do with charge phase. Can live in bulk as long as I want.

Originally Posted by Dan Best

>> 24hrs x ~3A x 12.5V = 900 Wh per day which is running my 100A alternator about 45 minutes a day

Unfortunately, unless you've got lithium batteries, your 100A alternater doesn't charge at anywhere near 100A unless your batteries are seriously depleted.

The acceptance rate of lead acid batteries decreases asymptotically to zero as the battery charges. I don't have the exact numbers in front of me, but basically this means that as your battery becomes more and more charged, it will accept less and less current. So if you start with a 50% depleted battery, it will accept a high charging current. This will gradually reduce as the battery becomes more and more charged. The last 20% and especially the last 10% may take many times longer that the first 20% or 10%. The actual acceptance rate is a function of the size of your battery bank, the kind of batteries and their state of charge.

[KP44]

Originally Posted by kev_rm

I am curious about the concern about energy use for electric autopilots?

I believe mine averages (over time, not instantaneous) less than an amp in calm conditions and ~3A when its busy.

24hrs x ~3A x 12.5V = 900 Wh per day.

which is running my 100A alternator about 45 minutes a day, so on a month long crossing that would use about 6 gallons of diesel on my boat.

help me understand the energy use problem?

(I understand the efficiency of charging, etc, so what, its 10 gallons..)

Modern autopilots use much less power. I don't know what "Wh" means. (Watt hour?) At your max of 3 amps, you're at 72 amp hours per day. A solar array with 10 hours of daylight should supply that most of the time. (Except when you need it the most. That's when a Monitor shines.)

At 3 amps and 12v (nominal) you're using about 40 watts of power; less than running lights used to need. Modern equipment draws much less power than what we needed a decade ago.

[wingssail]

I'll join the chorus for both windvane and autopilot.

We've sailed the majority of our 55,000 nm on a Monitor. It has been excellent in all wind conditions and directions. If the boat can sail, the Monitor can steer it. (I guess an exception will be under spinnaker; if the boat rolls the Monitor has not been able to keep up with the movement of the center of effort. Usually when sailing with a spinnaker I steer, it's fun anyhow).

Windvanes are not failure proof.

We have broken the Monitor. Trying to push 200mile days our boat develops heavy loads on the tiller (yes tiller) and the stresses on the Monitor have caused gradual breakages in the welds. We've had the unit reinforced and welded where the previous bolts were located.

We also broke the gear set when the boat heaved aftwards while hove to. This was serious and required machine shop work to repair it.

Finally, we've busted blocks and control lines.

So, for a powerful and fast boat, the Monitor is not bullet proof. Still we love it and use it virtually anytime we're sailing more than an hour or two.

Electric autopilot is essential.

We carry a Raymarine X5 Smart Pilot and a 4000GP drive unit. We use this when motoring. This device is too light for heavy wind sailing conditions and extensive use will wear out the drive unit within months of continuous use. in 25 years we've worn out three or four. We always carry a spare drive unit.

We keep our boat as simple as possible but we've rigged the Monitor to be able to control it from the cockpit (with a control line) and built a platform on the Monitor frame to allow easier lifting and lowering of the leg. We also take the lower leg off when in port because it's been hit twice by boats in marinas.

As for the Raymarine, we don't use a wind control vane on it, just the compass, which has been ultra reliable. We've stuck with the light duty because we have no access to the rudder post below decks, and little desire to upgrade an electric autopilot when we use it so little and the current one suits our needs. We mostly sail anyway.

BTW. We rig our gang plank, when tied stern to a dock, off the monitor frame.

[Gerrycooper56]

Used an autopilot on a Hunter 43 from Florida to Australia, no problem except cylinder leaks. Our Tayana was fitted with a windvane on the transom which we removed to enable stern access into the dink. The hydraulic autopilot is the way to go I think if you can power it, and as most people have solar panels/wind/generator this shouldn’t be a problem.

[Pegu Club]

Originally Posted by hpeer

OR you could do both.

Check out Pealigic.

https://pelagicautopilot.com/

Now these kinds of self steering are not precise. You don’t put in an exact waypoint, go to it and make a 30° turn.

So, as noted above, you need to think about what kind of sailing you will be doing.

This is what we use on our Monitor steering vane, when there is a head wind or no wind, works well, the pelagic tiller pilot is well built and very likely to have a long use life span. It is also quiet which we like. Just point to a given compass course, hit the button and your set, come to a turning point use the remote control to adjust course and you are again all set, easy peasy,

Fair winds,

[pelagic4005]

Short tacking I hand steer anyway. Longer tack out of Howe sound I connect the wind vane as I leave harbour. It is accurate reliable, feathers the boat in gusts steers down wind which no electronic System has ever done for me.

I like to keep my power for the fridge and electronics. With the solar panel and windcharger I am off grid so o ly need to fill with water

As others have me ruined it is possible to connect a small and cheap tiller pilot to the windvane if needed

Good luck and keep check the used sales as they come up frequently

[Michael Pope]

Why worry about charging rate. Its the discharging that causes all the noise.
The electronics lets you steer a compass course in light wind (when the vane is not responsive) or when you are powering in no wind. The vane works silently in wind but will take you where the wind shifts to.
I love the peaceful sounds of a sailing vessel.
My recent boats have no refrigeration because you do not need it and it is high maintenance (and I used to do that for a living) Been there done that!
I found sailing amongst low islands you needed compass courses as you can not see the Atolls if more than three miles away. I had solar but that was for the Sat-Nav (prior to GPS) and an evening chat with friends on Single side band.
I had a very quiet engine installation but it still frightened the fish I ate and smelled a bit.
A very good week was one where i had to run the engine to charge the batteries for an hour on Sunday Morning to drown out the poor children singing Hymns in church instead of the Raunchy native songs they sang and enjoyed on Friday night. Each to their own! Michael Pope

[gagrant]

I frequently use my electronic autopilot around my coastal cruising area for low winds or those “winds on the nose”days and you have to get somewhere. I have gone through 3 hydraulic ram rebuilds and 2 rams, as well as 2 hydraulic pump rebuilds and 2 new pumps. The new gear was purchased because I needed to something going quickly and had difficulty getting parts. I had to replace 2 electronic control boxes also as I could not really trouble shoot them myself. I now have one control box I cN send into be repaired while using the other. Replacing seals on rams and pumps is not that difficult -just messy. I eventually carried an extra ram, pump, and control box for the autopilot. More spares for the primary hydraulic steering.
I put on a hydrovane because i had hydraulic steering but also because I really liked the idea of a totally separate redundant rudder. The servo type (ie monitor) all work off the main rudder so it that goes down, you have no steering. I understand there are some mods you can make the monitor to make work as a separate rudder. On my maiden Hydrovane voyage to Hawaii and back from Vancouver the hydrovane stopped working in a nasty batch of weather. Eventually we realised the some of the set screws must have loosened and the “gear mechanism” fell apart and went overboard. Hydrovane was excellent to deal with. They stressed loctite for all screws. Obviously I will watch that carefully. Hydrovane worked brilliantly provider to trimmed sails appropriately. It seemed to do well on asymmetrical spinnaker and double polled headsails. At night the whine to the hydraulic pump on the autopilot was very noticeable in the aft cabin compared to the silence of the Hydrovane. You can also set up a tiller pilot on the hydrovane handle.
Short answer is I always will have both autopilot and windsteering for offshore but since I break everything, I have the parts to fix or replace, or rebuild as much as possible.

[merrydolphin]

I have a Monitor vane gear and THREE auto pilots. An older but dependable Benmar below decks, a RM wheel and a CPT wheel. There has been a couple of time that I have been down to one pilot, but with all the redundancy never with out! Ablsoulely the more the better. Especially with just a one or two person crew!