Hydraulic vs electric

[Souzag818]

Hello. I'm researching auto pilots and wondered what the brain trust thinks of hydraulic linear actuators vs electric linear actuators. Pros and cons of both. I've found conflicting information on which uses less electricity, so I'm confused. Also any thoughts on Pelagic AP, which seem to be hydraulic. This is all new to me so go easy, please...

[RaymondR]

from a design viewpoint one of the advantages of hydraulic systems in autopilot applications is that overload situations which would destroy a mechanical system are readily accommodated by pressure relief valves in the hydraulic system.

[wingssail]

Originally Posted by RaymondR

from a design viewpoint one of the advantages of hydraulic systems in autopilot applications is that overload situations which would destroy a mechanical system are readily accommodated by pressure relief valves in the hydraulic system.

On my Raymarine electric linear drive in an overload situation the control head detects the excess current and shuts off the power to the motor (and sounds an alarm). This requires a button push to restore operation. Nothing is destroyed.

Your Pretorien is a fine sailing boat. You could use (unless you have or plan to install an arch over the stern, a good windvane, like a monitor, and use a simpler, lighter, electric drive autopilot for those occasions when you don't have enough wind to sail.

[ronstory]

Another option is to look at the CPT autopilot. I have one and it is a very beefy but simple wheel autopilot that is also very miserly on power. It does not have the all the fancy features of the modern autopilots (like sail to wind angle), but it is simple and reliable.

My two cents. ;^)

[MikeHoncho]

Originally Posted by ronstory

Another option is to look at the CPT autopilot. I have one and it is a very beefy but simple wheel autopilot that is also very miserly on power. It does not have the all the fancy features of the modern autopilots (like sail to wind angle), but it is simple and reliable.

My two cents. ;^)

I second what he said. I’m very happy with mine.

[Souzag818]

Your Pretorien is a fine sailing boat. You could use (unless you have or plan to install an arch over the stern, a good windvane, like a monitor, and use a simpler, lighter, electric drive autopilot for those occasions when you don't have enough wind to sail.[/QUOTE]


I have a Raymarine wheel auto pilot (I'm not sure of the model and am not at the boat) that I use when there is no wind or it's under 10 knots. It works fine for those conditions, but above 15 knots, while sailing, it's over powered. I want something that can sail the boat, while I reef, and steer it once I have. Now it takes 4 or 5 trips from the cockpit to the mast to reef, running back to the cockpit to get the boat back on course, back to the mast to reef, back to the cockpit to get on course...Kinda takes the fun out of it...

[wingssail]

Originally Posted by Souzag818

Your Pretorien is a fine sailing boat. You could use (unless you have or plan to install an arch over the stern, a good windvane, like a monitor, and use a simpler, lighter, electric drive autopilot for those occasions when you don't have enough wind to sail.

I have a Raymarine wheel auto pilot (I'm not sure of the model and am not at the boat) that I use when there is no wind or it's under 10 knots. It works fine for those conditions, but above 15 knots, while sailing, it's over powered. I want something that can sail the boat, while I reef, and steer it once I have. Now it takes 4 or 5 trips from the cockpit to the mast to reef, running back to the cockpit to get the boat back on course, back to the mast to reef, back to the cockpit to get on course...Kinda takes the fun out of it...[/QUOTE]

Windvane

[Paul L]

Originally Posted by wingssail

On my Raymarine electric linear drive in an overload situation the control head detects the excess current and shuts off the power to the motor (and sounds an alarm). This requires a button push to restore operation. Nothing is destroyed.

.......

And when this happens as you are accelerating down a large sea in 35 kts the boat basically now has no one steering it and it is free to round up beam to the breaking sea. This is the biggest reason I don't like Ray autopilots. This mode is designed to protect the autopilot, not the boat and crew.

[bensolomon]

Originally Posted by ronstory

Another option is to look at the CPT autopilot. I have one and it is a very beefy but simple wheel autopilot that is also very miserly on power. It does not have the all the fancy features of the modern autopilots (like sail to wind angle), but it is simple and reliable.

My two cents. ;^)

I have a CPT as well. I love it! Simple, low power draw, and very tunable. I've used it in 20 knots and as long as my sails are balanced, no problem.

Sailing in 15 knots with cpt:
https://youtu.be/RyBtTZZPhus

Spinnaker low wind but good look at CPT:

https://youtu.be/BzqWCvYMs14

Ben

[Souzag818]

Windvane[/QUOTE]




I don't have any plans to go long distance cruising in my boat. I would get a windvane over an autopilot for sureif I did. I just need something for cruising around the PNW, crossing the Straights, etc. A good autopilot has to be better than bad crew...

[Souzag818]

Originally Posted by bensolomon

I have a CPT as well. I love it! Simple, low power draw, and very tunable. I've used it in 20 knots and as long as my sails are balanced, no problem.

Sailing in 15 knots with cpt:
https://youtu.be/RyBtTZZPhus

Spinnaker low wind but good look at CPT:

https://youtu.be/BzqWCvYMs14

Ben

I actually looked at those. I liked the simplicity. The biggest problem is my boat has a very small cockpit. Good for ocean sailing, not too comfortable otherwise. I can't imagine two or three guys/gals jibing a spinnaker in the confines of my cockpit. I don't need stuff taking up what little real estate there is.

[more]

Originally Posted by Souzag818

Windvane

I don't have any plans to go long-distance cruising in my boat. I would get a wind vane over an autopilot for sure if I did. I just need something for cruising around the PNW, crossing the Straights, etc. A good autopilot has to be better than bad crew...[/QUOTE]

both have positive - negative side.
for you important is space can you put electric or you need short strong hydroulic ram.

Why somebody today want wind wane. so complicate expensive system for maybe 1-2 trips over Atlantic and maybe save 500w dayAnd also windwane don't have wifi, bluetooth routing alarm

[wingssail]

Originally Posted by Paul L

And when this happens as you are accelerating down a large sea in 35 kts the boat basically now has no one steering it and it is free to round up beam to the breaking sea. This is the biggest reason I don't like Ray autopilots. This mode is designed to protect the autopilot, not the boat and crew.

Yes Paul, that would be unpleasant, and for that reason I don't use the autopilot when sailing, and especially in heavy winds. We use the Monitor windvane which handles those situations very nicely.

We each equip our boats to suit our needs and cruising habits and style.

For us, less is more. We'd rather not install the equipment for a heavy duty autopilot, to say nothing of making the modifications to the boat to permit its use. The autopilot for us is just for motoring or very light conditions.

We almost always sail when underway and we keep our boat light and simple and avoid continuous power usage and guaranteed periodic autopilot maintenance or breakdowns by depending on the wind vane.

I have to say that when faced with a problem we always try to avoid a solution which incudes adding anything bigger, heavier, more expensive , more power hungry or complex, even if is deemed "best".

Our "less is more" approach has worked for us for 35 years of cruising.

[seandepagnier]

Originally Posted by Souzag818

Hello. I'm researching auto pilots and wondered what the brain trust thinks of hydraulic linear actuators vs electric linear actuators. Pros and cons of both. I've found conflicting information on which uses less electricity, so I'm confused. Also any thoughts on Pelagic AP, which seem to be hydraulic. This is all new to me so go easy, please...

Electric mechanical is about twice as efficient as hydraulic for the most part. It depends on the exact setup and actuator as well, but generally hydraulic uses more power to do the same thing because there is considerable friction in the seals. There is also probably a lot more friction moving the rudder manually with hydraulic installed despite bypass valves, this all adds friction. Larger boats that do use hydraulic tend to be heavier and have slower corrections using less power than smaller boats relative to their size, so although they use more power especially with hydraulic, power use does not scale based on displacement.



Even if the power consumption of the autopilot is double from hydraulic, the amount of power difference is generally a small fraction of the available power from solar and not always important.



There is little risk of damage if the motor controller detects stalls, but especially if there is rudder feedback. This is needed to prevent stress on hydraulic systems as well.



As for the electronics, they generally don't care what they are driving, however because hydraulic draws more power the motor controller needs to be able to supply the current. For this reason I sell the pypilot hydraulic controller for twice the price of the regular controller. The actual tinypilot computer itself that performs the course calculations used are the same either way.

[Paul L]

Originally Posted by wingssail

Yes Paul, that would be unpleasant, and for that reason I don't use the autopilot when sailing, and especially in heavy winds. We use the Monitor windvane which handles those situations very nicely.

We each equip our boats to suit our needs and cruising habits and style.

For us, less is more. We'd rather not install the equipment for a heavy duty autopilot, to say nothing of making the modifications to the boat to permit its use. The autopilot for us is just for motoring or very light conditions.

We almost always sail when underway and we keep our boat light and simple and avoid continuous power usage and guaranteed periodic autopilot maintenance or breakdowns by depending on the wind vane.

I have to say that when faced with a problem we always try to avoid a solution which incudes adding anything bigger, heavier, more expensive , more power hungry or complex, even if is deemed "best".

Our "less is more" approach has worked for us for 35 years of cruising.

Nice justification for your sailing situation. Not a justification for the way Ray handles the fault condition. It should fail safe and attempt to continue steering even after alarming.
We use our AP 100% on passage, so I want it to work properly.