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Old 24-11-2013, 12:40   #16
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Re: auto pilot system

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Originally Posted by colemj View Post
Their website talks specifically about interfacing with Loran.
Well then. It must be the Alpha web site that's showing some age.


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Originally Posted by colemj View Post
Yes, a complete disconnect takes out all friction, but modern drive units have almost no friction now. I certainly cannot tell the difference between our drive connected with the clutch off and disconnected completely from the quadrant arm.
Assume you have a linear drive and not a hydraulic unit. My research on hydraulic AP drives shows they include a bypass for the fluid when the drive is not active and I have heard comments that there is some restriction in the fluid flow through the bypass.

Which brings another question. I have seen a number of recommendations for hydraulic drives being more reliable than mechanical drives. But my question is the power for either system comes down to an electric motor which I would think the most likely failure point so why is the motor in a hydraulic drive supposedly more reliable than the motor in a linear drive unit?


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I would certainly find it a pain, if not downright dangerous, to have to align the rudder and drive unit, then pull a cable and rock the wheel each time I needed to engage the AP.
It does sound like a pain but have never read a single complaint about the function so it must work better than it sounds.


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Power draw is a function of the drive unit, the boat balance and the steering qualities.
Which is the reason it is so difficult to compare power draw between different brand autopilots. You would have to install different APs on identical boats and sail in identical conditions with identical sail trim and balance to get exact comparisons.

One reason Alpha claimed to draw less power than older gen APs was other brands used extra power to keep a clutch engaged to drive the rudder where the AP did not (because of the drive?).


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Originally Posted by colemj View Post
Other modern units use ball drives, etc and have low power consumption. When we replaced our old B&G system with a new Simrad AP, our power draw dropped from 13-15A to 3-5A!
That's very interesting information for me. Simrad is certainly on my short list for when I upgrade. But referring back to my comment above, what kind of drive are you using with the Simrad?


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I understand some do not want integration capabilities, but I don't understand why they would pay up to twice as much to not have them.

Again, I'm sure to take heat on this, but I fail to see any reason to get one of these systems - particularly since better performing and more feature-rich systems exist for less money.

I have actually heard from users that Alpha's support and service is very good.

Mark

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Originally Posted by colemj View Post
I understand some do not want integration capabilities, but I don't understand why they would pay up to twice as much to not have them.

Again, I'm sure to take heat on this, but I fail to see any reason to get one of these systems - particularly since better performing and more feature-rich systems exist for less money.
It would indeed defy logic to pay more just to not have a feature but I'm guessing the perception is the higher priced unit works better, is more reliable or offers some other benefit. But twice as much? Don't recall the exact numbers but when I researched below decks APs I thought the price for all of them were in the $4-$5,000 range.


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Originally Posted by colemj View Post
I have actually heard from users that Alpha's support and service is very good.
Years past I saw a few comments from users that had problems with support when they had problems while outside the states and had limited options to send the units back to the factory.
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Old 24-11-2013, 17:08   #17
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Re: auto pilot system

I have just purchased and installed a Garmin GHP12 on a 43' sailboat 24,200lbs.
It replaces the electronics of a Robertson AP300 system and utilises the same hydraulic actuator and pump.
Total cost USD3,200 including additional cables and a RF remote.
Have yet to test it in tough sailing or motoring conditions but have some longer trips coming up and will get some testing time.
IN calmer conditions it responds well under motor and has been easy to teach others on board to use.
Like the remote as can be used in most places on board.
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Old 24-11-2013, 18:11   #18
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Re: auto pilot system

Quote:
Originally Posted by skipmac View Post
Well then. It must be the Alpha web site that's showing some age.

Assume you have a linear drive and not a hydraulic unit. My research on hydraulic AP drives shows they include a bypass for the fluid when the drive is not active and I have heard comments that there is some restriction in the fluid flow through the bypass.

Which brings another question. I have seen a number of recommendations for hydraulic drives being more reliable than mechanical drives. But my question is the power for either system comes down to an electric motor which I would think the most likely failure point so why is the motor in a hydraulic drive supposedly more reliable than the motor in a linear drive unit?

It does sound like a pain but have never read a single complaint about the function so it must work better than it sounds.

Which is the reason it is so difficult to compare power draw between different brand autopilots. You would have to install different APs on identical boats and sail in identical conditions with identical sail trim and balance to get exact comparisons.

One reason Alpha claimed to draw less power than older gen APs was other brands used extra power to keep a clutch engaged to drive the rudder where the AP did not (because of the drive?).

That's very interesting information for me. Simrad is certainly on my short list for when I upgrade. But referring back to my comment above, what kind of drive are you using with the Simrad?

It would indeed defy logic to pay more just to not have a feature but I'm guessing the perception is the higher priced unit works better, is more reliable or offers some other benefit. But twice as much? Don't recall the exact numbers but when I researched below decks APs I thought the price for all of them were in the $4-$5,000 range.

Years past I saw a few comments from users that had problems with support when they had problems while outside the states and had limited options to send the units back to the factory.
From their website, the basic package will cost ~$5,600. If you want a gyro compass with the ability to connect a wind instrument and a computer (half of the functionality of a modern AP), then the costs go north of $6,600. A comparable Simrad system that includes complete electronic integration capabilities, waterproof control head and far more functionality will cost ~$3,500. Heck, upgrade that to the larger system and it only sets you back ~$4,400 - still less than Alpha's basic system.

We have a Raymarine electromechanical drive. It has no backdrive pressure at all. Our old B&G hydraulic drive had tremendous backdrive pressure. I have been told that the newer hydraulic drives do not have much backdrive pressure at all, although I do not have first hand experience with them.

Our B&G drive was mostly trouble-free for 13yrs - I had to replace a seal and the motor brushes. I expect the same from the RM mechanical drive. The hydraulic drives produce a bit more torque and thrust than the mechanical drives and have less moving parts. The mechanical drives have a whole planetary gear system and ball screw going on compared to hydraulic drive's simple check valve system. When a mechanical drive does goes tango uniform, it is pretty much done, where a hydraulic drive can be rebuilt almost anywhere. But, like I said, I expect the same trouble-free existence with our mechanical as I did with our hydraulic.

I have sailed on boats with an Alpha, and the fact that the owner's do not complain about the engagement mechanism surprises me. They have either drank that kool-aid or have never used another type for comparison.

The clutch uses very little power - maybe 0.5A. I guess that adds up over time, but is not a good reason for putting up with a cumbersome mechanical engagement mechanism.
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Old 24-11-2013, 18:19   #19
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I just had a Simrad DD15 drive unit matched to a garmin ghp20 autopilot and matching rudder sensor. I also have an airmar 200wx weather station. Very simply here is why I think this is a great combination... 1) the dd15 unit is extremely robust and can be fit into tiny areas. It is commonly considered one of the best drive units on the market. It is small enough to be used in very confined spaces, can be used in a boat in place of a larger unit to save space, and can be used on boats with a high dead rise, which can prevent most all non pancake drive units from fitting at all. 2) the Garmin autopilot unit is also robust in features but is much cheaper than the competition (I did look closely at Simrad units). It also integrates tightly with the wide range of affordable garmin companion products. Combined with the extremely accurate airmar unit, it provides very good wind follow and current drift calculations. I do think you would have a hard time finding a better package. However..... Wind vanes still rock. I really wish I could add one but it's a trade off for davits.
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Old 24-11-2013, 18:32   #20
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Re: auto pilot system

Simrad doesn't make the DD15 - they buy it from Jefa and rebrand it. Not that it makes any difference, but I thought it may be good info for you.

Mark
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Old 24-11-2013, 18:36   #21
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Quote:
Originally Posted by colemj View Post
Simrad doesn't make the DD15 - they buy it from Jefa and rebrand it. Not that it makes any difference, but I thought it may be good info for you. Mark
Good point... I should have mentioned that.

Also, they make a bigger unit if you need it. I also failed to mention it has one if the lowest power consumption profiles of any drive unit.
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Old 25-11-2013, 18:58   #22
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Re: auto pilot system

This is not so much a reply but a plea for help.
I have a Navman G-Pilot 3100 in working order, including interface with a 3100 wind display, except that the control head display is now completely blank and blacked out so that, other than by trial and error, I have no idea of what is actually happening. The blankness is, I am told, due to cheap specification of the ribbon connections between PCB and LCD but the black out is, I am alsotold, due to moisture getting between the layers of the LCD and steaming the individual layers into oblivion. There is, therefore, no point in trying to repair the control head and, even if I manage to find a second hand or unused one, it will have the same generic fault and fail sooner or later.
Several people have told me that, if I replace the control head and the computer, it should be capable of controlling the hydraulic pump, which predates the installation of the Navman, and the rudder angle input, fluxgate compass and the wind direction data should all be able to supply usable data to the computer and the system should work as before.
Unfortunately, 'should' appears to be as close as anyone is willing to go. Can anyone enlighten me further or point me in the direction of an idiot's guide.
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Old 25-11-2013, 20:06   #23
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Re: auto pilot system

Hi Galleyslave

Can understand your frustration withe the Navman system only glad we did not install Navman a few years back when our Robertson started giving trouble.
My first suggestion would be to talk to a Simrad agent as Navico who owns a lot of the brands bought the Navman/Northstar brand.
Your compass and hydraulics and rudder feedback "should" all be re-usable but they don't make up the expensive parts of the auto pilot system.
The computer control unit and the head unit are most likely the more expensive items. Example would be Simrad AP24 Display and AP12 computer cost around USD2600.
Plus installation.

Sorry its not good news, just being realistic and most of us rely on AUtopilots while shorthanded.
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Old 25-11-2013, 20:20   #24
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Re: auto pilot system

Raymarine Evolution. No contest. Most modern and best there is today. Drive is up to you...
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Old 25-11-2013, 20:39   #25
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Re: auto pilot system

I was thinking of going with a Comnav 1420 and a raymarine linear drive. I've seen a lot of reconditioned newer raymarine control heads for sale already and wonder what kind of track record the evolution stuff has.

It is not interchangeable with any of the older control parts which are easy to find.

Any comment on the comnav? They are cheap and supposed to be super reliable.
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Old 25-11-2013, 21:00   #26
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Re: auto pilot system

Use the google custom search. I have seen good responses on the Comav. I can't remember any negative responses.
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Old 03-11-2014, 20:52   #27
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Re: auto pilot system

Follow up to my previous post about Garmin GHP12 autopilot.
We have been using it for a year now and on reasonably long coastal voyages. (120Nm)
It has performed well and handled large wave states and wind speeds. Came through strong winds 30knots gusting 40knots on a reach in 10foot confused swell without tripping out or stalling the sails.
Two problems:
1. the compass was initially mounted too close to the alternator on the engine and this would throw the course out when the alternator was loaded up. Easily fixed with a change in the location of the compass.
2. The wireless remote losing connection with the head unit. Traced this down to the head unit being mounted on the nav station which was partially shielded by the galley fire shield. Shifted the head unit up to a different location and wireless remote now works all over the yacht.
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