One Boat, Two Autopilots ??

[Jeff Bacon]

Hi All:My h386 has an ST 4000 autopilot installed. This is a marginal solution for a boat of this size and weight, but the original decision a few years ago was a budgetary decision.In Annapolis, I bought a Raymarine below decks Corepack system that is appropriate for my boat, and will install it this spring. However, since the operating power requirements for the larger system are signifigantly more than the old ST 4000, I have been wondering if I can have both systems installed. I am thinking that I can use the smaller pilot during those lazy light wind sails in flater seas, then use the larger pilot for conditions that exceed those just described.If this was an original installation, I certainly would not do this, but, since the smaller pilot is already installed and working, I am thinking "why not".I cannot come up with any drawbacks, but I am not sure if I could hook both up to the sea talk system. and, of course, both couldn't be operating at the same time. I also imagine that the two fluxgates shouldn't be too close together.I think the power savings on a 6 or 7 hour sail migh be very noticeable.Any thoughts ??Thanks ....... Jeff

 

[Jack Tyler]

That all makes sense to me, Jeff

You obviously have to be 'stay in control' and avoid both units suffering from a mutual conflict...but that aside, why not? Your fluxgate compasses could be mounted adjacent to one another, IMO. FWIW I move between two different a/p's sometimes, when shutting down the wheel pilot and engaging the tiller pilot I sometimes use with my wind vane. As long as the two systems on your boat are independently powered (and you use some kind of interlock, mental or other, to avoid them both being powered concurrently), your arrangement isn't any different - conceptually - than mine.Jack

 

[Reudi Ross]

That should work

You could install a single pole double throw power switch at the DC panel so that one or the other would be powered up but never both at once. It might be worth a call to raymarine tech support about the fluxgate compass sensors, it may be possible to share one compass for both pilots.

 

[Dan Jonas]

Red Wire?

It seems to me that both autopilots are likely to be connected to the SeaTalk bus. If so, and wired according to Raymarine recommendations, the red sire from the Sea Talk bus will power up both autopilots (although without sufficient power to run either in auto mode). There is no problem that I can see in leaving one in standby mode, but I'm curious how you will disconnect the power from SeaTalk without compromising the SeaTalk data (according to Raymarine).This red wire connection has always troubled me. It seems that the design should allow powerup of the head, but refuse a command for auto mode.By the way, I have two boats. On the first, I left the red wire disconnected. On the second, I wired to Raymarine specs. I can't tell the difference, but Raymarine says there is a potential data problem.Dan Jonas (S/V Feije II)

 

[jmcclain]

Two autopilots!

Jeff,I don't see any reason technically that mounting both will not work provided that you power both instruments external to the seatalk power run (the RED wire) and, as suggested earlier, switch so that only one is active at any time. My real question to you is why? The power consumption of the ST4000 about 1 AMP. The consumption of below deck unit with a type I actuator is from 1.5 to 3 AMPs. The difference during light demand is only about 10-12 AMP/HRS in 7 HR sail. The response time for the below deck unit is much better. You will also need to find helm space for two control displays. They are not the same. It it were me, I would remove the ST4000 components, clean and package them and sell it on Ebay. They are going for $300-$500. Then, take the money and increase the battery bank size and get a battery monitor to keep an eye on everything. You will also unclutter the cockpit and have the option of easy wheel removal when setting at the dock.Jon McClain s/v Parrot Tales, B321

 

[Ed Schenck]

Jon's pretty smart.

I started to answer this earlier Jeff. Glad I didn't, I like Jon's answer much better.

 

[Jeff Bacon]

Jon....

.... I guess your question as to why is really my question as well. I don't know if I am reading the specs properly, but the new system indicates that the Drive Motor can draw 5 amps, the drive clutch indicates 1.5 amps (do we add these together ?).Maybe a better question for an electrical neophyte like me is - Does the motor only draw what it needs, or is it a constant draw whenever it is working ?Never thought about Ebay, and batteries and a monitor are on my list anyway.Thank you, Jon.

 

[Jeff Bacon]

Power update on new system...

Just went to Raymarine website and got the following infoCorepack draw (S2G system) - 15 to 18 ampsClutch draw - 5 ampsDrive Motor - 24 to 48 watts (forget how to convert to amps

 

[jmcclain]

More on Two Autopilots!

Jeff,My original quick math was based on the smaller and simpler S1 Corepak that draws less than the S2G. WATTS/12.6V = AMPS. Original comparison is fairly accurate except that I forgot about the electric clutch on the S2G.ST4000: About 1 amp on standby. 4 to 8 amps engaged.S2G: 15 amps on standby, 20 to 23 amps engaged. + Motor Drive at 2 to 4 amps only when making steering correction.For 7 hr. sail you are still only looking at about 170 amp hrs max. This is if you never turned it off or ran diesel. One additional 4D battery would be more than adequate. Another problem that you will have to address with two separate pilots is how to mount two rudder position transducers. Not sure that can be done.Even if you managed to get both autopilots synchronized, the S2G is so superior in featues and response that my guess is you will never use it.Good LuckJon

 

[Jeff Bacon]

Thanks, Jon

I appreciate your input. During this thread I asked Raymarine what they thought via their website, and will post their answer here for general info.This looks like a perfect opportunity to upgrade my batteries !