Autopilot Control Unit Choice

[Winf]

Hiya

Any comment/advice appreciated.

Require a new autopilot for our yacht - still working out a solution.

The Jeffa Direct Drive type 1 unit (DD1) seems to offer a compact solution and i am more than likely going to go with that.

Wanting to go with Raymarine autopilot control unit to marry with other onboard systems. The two Raymarine ACU’s looking at differ in maximum output amperage (15A for ACU200, 30A for ACU400) also in maximum clutch current output (ACU 400 is 4 Amps with ACU 200 at 2 Amps.)

The Jeffa website indicates that both the ACU200 and 400 are able to drive the unit with no difference in output torque.

From what I can see the DD1 clutch only draws 1.4 Amps max.

Put another way, if 80Nm of torque is required at midships, the DD1 will draw 13 Amps. That is approx 86% of ACU 200 max output compared to 43% of max output for the ACU 400. Similar idea for the clutch.

So the larger control unit seems to offer no mechanical advantage or any greater power consumption but it will operate at a lower % of its max capability. This may I suspect impact on overall life span type factors of the ACU rather than actual performance.

I am not trying to save money if that means poorer performance autopilot but am I correct in saying that either ACU unit will drive the DD1 equally, the 400 will simply work less?

I may have answered my own question with this but am I missing something here?

Anyone out there with any experience with the Jeffa DD1 coupled with the ACU200 or 400?

Oh, asked Jeffa and they were not able to assist.

Thx

Wind

[NSboatman]

I’ve been very happy with my Garmin GHP 12 control head coupled to an L&S electro-hydraulic ram. Steers dead straight in most conditions up to very chaotic, and is quiet and relatively economical in terms of power burn. Jefa is good gear too. No recent experience with Raymarine AP’s tho.

[Bill O]

Look at Pypilot. Sean has a controller to handle your amp draw. We are happy with our configuration and his controller can easily handle our large below deck hydraulic AP pump.

Rather than rewriting how we did everything, here are links to our write ups we did on creating our nav. computer w/a RPi and using pypilot to control our AP. Very simple to setup when you go through OpenPlotter.


Bill O.

[blubaju]

Originally Posted by Winf

Hiya



Any comment/advice appreciated.



Require a new autopilot for our yacht - still working out a solution.



The Jeffa Direct Drive type 1 unit (DD1) seems to offer a compact solution and i am more than likely going to go with that.



Wanting to go with Raymarine autopilot control unit to marry with other onboard systems. The two Raymarine ACU’s looking at differ in maximum output amperage (15A for ACU200, 30A for ACU400) also in maximum clutch current output (ACU 400 is 4 Amps with ACU 200 at 2 Amps.)



The Jeffa website indicates that both the ACU200 and 400 are able to drive the unit with no difference in output torque.



From what I can see the DD1 clutch only draws 1.4 Amps max.



Put another way, if 80Nm of torque is required at midships, the DD1 will draw 13 Amps. That is approx 86% of ACU 200 max output compared to 43% of max output for the ACU 400. Similar idea for the clutch.



So the larger control unit seems to offer no mechanical advantage or any greater power consumption but it will operate at a lower % of its max capability. This may I suspect impact on overall life span type factors of the ACU rather than actual performance.



I am not trying to save money if that means poorer performance autopilot but am I correct in saying that either ACU unit will drive the DD1 equally, the 400 will simply work less?



I may have answered my own question with this but am I missing something here?



Anyone out there with any experience with the Jeffa DD1 coupled with the ACU200 or 400?



Oh, asked Jeffa and they were not able to assist.



Thx



Wind

Jeffa can't help you as you ask about the AP-computers power.

You did not mention your yacht size. My 43ft (13.2m) catamaran is steered by the smallest jeffa sprocket drive, no problem last 10 years. I did change my Raymarine AP & MFD to B&G though, the system from 2009 was just to slow in reacting and the E120 display circuit died.

Jeffa is usually not consuming maximum power too, no sense to select a to large system.

[Sailmonkey]

Your correct in your assumption that both pilots are able to deliver the maximum required current of the ram.

Imho, working an electronic component at a lesser percentage of maximum equates to less waste heat. Meaning longer life.

[blubaju]

Originally Posted by Sailmonkey

Your correct in your assumption that both pilots are able to deliver the maximum required current of the ram.

Imho, working an electronic component at a lesser percentage of maximum equates to less waste heat. Meaning longer life.

Yes, but at what percentage of maximum load is your AP running? And what percentage of time? I never noticed a significant temperature change in my system, never ever near the hypothetical 86% for any longer time. I did not go for it as the current draw is higher and electricity is always critical on board.

Every Yacht is a compromise of priorities

[mvmojo]

I'm a fan of having a larger system than the "specs" call for. Under normal conditions the smaller unit may run fine, but when you're up to it in wind, waves and current and the boat is getting tossed and/or slung around, you don't want your autopilot running at max capacity and failing at the wrong time. Having more power can only help you. Try not to over analyze it. Spend the extra $$$ for the larger unit and only cry once!

[tarian]

Hi my boat is 42ft and 13 tonn and the raymarine acu 200 and jeffra is more than enough
Maybe your overthinking it and just og with the manufacturing recommendations in which the Acu 200 is plenty for your size of boat and on the jeffra site it gives the displacement and general length for their units and it says will work with all raymarine Acu units
If it's power consumption tnen you need to work out is the price difference worth your batteries been drwn a little more

[guyrj33]

Within reason both control units will consume the same amount of power and generate the same amount of heat. The power used is limited by the autopilot drive.
The larger drive will be operating at a lower percentage of total capability and will therefore dissipate generated heat in the controller with a larger margin.

[deblen]

If you are starting from scratch,have you considered a Raymarine M81130 type electro mechanical linear drive. Very reliable. / Len


Mechanical Linear Drives | Raymarine

[Winf]

Thanks for the responses so far.

Boat is 36' mono.

I really don't have a lot of space available. The Jeffa DD1 is the drive unit I have found that will fit in with the least mods.

Some responses so far seem to confirm what I thought - power consumed depends primarily on the drive unit, not the controller.

Different controllers would I assume have differing response algorithms to tell the drive what to do to keep on track. I can see how that may influence power consumption but my guess would be that the two Raymarine units in question will differ only in how much output they can deliver to the drive unit.

So the issue is not higher power consumption by a larger ACU, it is where the ACU is operating on its performance curve.

Winf

[MAJICDAN]

I have given up on Raymarine.
Raytheon made wonderful products that seemed to last forever and never broke down.
When Raymarine took over the quality went downhill to where we are today.

I am in the process of changing everything over to Garmin.
I just purchased a Garmin Sailing autopilot system GHP-12. Since my sailboat weighs about 55,000 lbs, I have fitted it with the Class B Hydra electric drive system.
This is specifically a sailboat system not a power boat system for sailboats.
It will interface with my 15in Garmin chart plotter.

[Mike Banks]

In Australia TMQ is the way to go--I had a hydraulic one--worked perfectly for years with never a problem. It is what most of the commercial vessels use--and for good reasons. RELIABILITY and STRENGTH. Only trap for hydraulic steering is if you wish to resume control of the helm, you must first turn off the autopilot, or the wheel turns and nothing else happens.

[mikedefieslife]

Originally Posted by deblen

If you are starting from scratch,have you considered a Raymarine M81130 type electro mechanical linear drive. Very reliable. / Len


Mechanical Linear Drives | Raymarine

This is a final drive unit, the OP has already chosen the Jefa unit which will work equally well, and is maybe even better quality.

I do agree that electric linear or other electric drives are the way to go though. I have the ACU200 driving an unknown vetus branded hydraulic pump which in turn pushes two (in series) MTC72 rams. The setup regularly spikes to 10amps when correcting course. From what I've read, the electric drives are much more efficient.

[Bill O]

Originally Posted by Mike Banks

In Australia TMQ is the way to go--I had a hydraulic one--worked perfectly for years with never a problem. It is what most of the commercial vessels use--and for good reasons. RELIABILITY and STRENGTH. Only trap for hydraulic steering is if you wish to resume control of the helm, you must first turn off the autopilot, or the wheel turns and nothing else happens.

Will agree about the reliability and strength of the hydraulic pump/steering, but must be a quirk in your system because we can steer while the AP is on, no problem. Do you have a engagement clutch/valve that isolates/removes helm steering when the AP is engaged?

Originally Posted by mikedefieslife

I have the ACU200 driving an unknown vetus branded hydraulic pump which in turn pushes two (in series) MTC72 rams. The setup regularly spikes to 10amps when correcting course.

We have a heavy duty pump controller (developed for Pypilot) and one of the largest hydraulic pumps in the recreational market for our large ram (~540 cc/33 cu. in). We don't see those kind of spikes when correcting course and is typically low amp draw. We also experience fairly low Ah w/the Pypilot software. Couldn't tell you what exactly is the difference between the systems, but the nice thing in the Pypilot software is you a can easily see the power consumption and adjust sails, etc. for better efficiency.


Bill O.