Hydraulic AP Pump Install

I was hoping to find a mechanic who could hook up my new autopilot pump. I have one last call in, but I can already see where this is going. If it's going to get done before June, there's a good chance it's going to be me doing it.

So, all you hydraulic experts, I'll have some questions.

First, some background. It's a two-helm system, three copper tubes, reservoir in the ER, relief valve aft not too far from the cylinder.

1) Pump Location. I'm thinking the best place for the pump would be in front of and below the lower helm. From there, the three hydraulic lines disappear below decks and ultimately "T" in with the three from the flybridge. Any reason this would be a bad spot?

2) Connection Location. Could I "T" off the connections at the helm pump? Do I have to cut in somewhere between it and the rest of the system?

3) Tools and Parts. I've never fabricated hydraulic lines, only disconnected & reconnected them. What do I need? Flaring tool? How fancy does it need to be? Any decisions to make on which fittings to buy? Copper tubing or something else?

I'm sure there will be more. Thanks in advance for any suggestions.

Not difficult. The exact location of the tie-ins is not important. You can tee off the lower helm or splice into the lines.

A hydraulic shop can provide you with hoses and fittings, just take them an example. I did most of my system with copper and flares, but the pump has three flexible hoses to reduce noise coupling.

I put my pump in the engine room so I would not hear it. This is a pretty big deal, especially on a quiet boat. Pump sort of sounds like a weedeater, and if you like that kind of noise you are weird.

I just installed a AP on the hynautic steering system on my boat. The compensating line was the only one that had certain area in the system to tap into. Here is some information from my manual.

Ports A and B in the diagram above are the input/output ports of the pump and must be connected to the steering lines coming from the steering cylinder. It does not matter which pump port is connected to which steering line.
Compensating Line:
Port C is the compensating or bleed line, and must be connected to the steering system's reservoir. This connection can be made at: a helm pump, the remote reservoir (if there is one), the compensating line connecting two helm pumps, or the compensating line connecting a helm pump to the remote reservoir. If the connection is being made directly to a helm pump, ensure that the bleed line is connected to the LOWER helm’s bleed port.
The compensating line MUST have a gradual rise from the pump to the connection to the steering system. This allows air to rise out of the pump, ensuring a constant supply of oil to the pump.


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When purchasing Hyd lines be sure to specify swivels at BOTH ends.

I’ll wager your steering system looks a lot like mine and after a year of gathering information, tools and materials, I determined I’d have to locate a competent yard to do the work. After a few disappointments and goose-chases, I found a yard in Solomons, Md. who was confident they could do the work. The estimated time for a Garmin GHP20 AP unit for a twin helm, Capilano ram hydraulic steering system was 45 hours. I had already mounted the compass, (low in the forward berth), and the pump, (on a plywood pedestal) in the rudder lazarette at the transom. I had also run some of the cabling, but by that time I realized I was in over-my-head with the hydraulic connections. The installation and sea-trial time was in reality 54 hours. The additional time was due to running and “hiding” molded Garmin cabling, and, much consultation with the Garmin technical people in getting the AP to behave as it should on the sea trials. I don’t know what your AP unit is, but if interested I have a fairly detailed Garmin schematic with my notes I’ll send to you, but in retrospect, I am happy to have had an expert do the installation.

45 hours of labor? Wow. Fortunately, all I need is to have the hydraulics hooked up. One guy said a half-day, maybe a day. Another guy hasn't called back yet. Talking with other owners at the marina who have done it, I now have the name of a supposedly great hydraulics shop, along with a little more confidence.

I'm liking the idea of flexible hose from the "T"s to the pump. One, because I'm not that confident in my ability to form the copper tubing without squashing it, and two, because it'll maybe isolate some of the vibration.

Interesting suggestion on the swivels. I'll ask about that when I bring everything to the shop. First I have to get down to the boat, take some pictures and measure the OD of the existing tubing with calipers.

I've seen the Garmin instructions (and video) as well as the Simrad ones that came with my set. It looks like my preferred location for the pump is going to work just fine. My big dilemma is whether to set it on the deck of the stowage compartment, where it'll be easy to get at but subject to being bumped by parts and tools, or just below that in a compartment that's hard to squeeze into and work, but should be well protected, and isolate the sound better.

Speaking of sound isolation, any suggestions on a mounting block for the pump? Ideally I'd like to put something flexible between it and the deck.

It took a hour at most to do the pump plumbing, had all the fittings and new lines. I still have to fill reservoir with oil and charge air pressure and bleed system, I've did this when I re-sealed the helm pumps and it may take a hour. I had to leave the boat and come home for Easter with my daughter's family, will head back next week.


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CaptTom said:

Speaking of sound isolation, any suggestions on a mounting block for the pump? Ideally I'd like to put something flexible between it and the deck.

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Most pumps do not create much airborne noise, so what compartment the pump is in should not impact noise very much if at all. "put something flexible between it and the deck" is typical, and fine if the isolation medium is soft enough, but as soon as you put a fastener through a sheet of something you "short circuit" whatever isolation may have been there.

Best vibration isolation is a small isolation mount sized for the weight and loaded properly. This usually means mounting the pump on a plate or piece of plywood and putting 4 isolators equal distant from the CG. The Rubber grommets on the pump do not account for the weight of the pump head and attending plumbing and oil.

Any mount like these spec'ed for the weight of your unit will work best.

Keysdisease said:

Most pumps do not create much airborne noise

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Ours sounds like a quacking duck in the mater bathroom which is under the lower helm. :lol:

A street walking duck may have slipped on when you weren't watching!

And the pump may be mounted to the deck which is transmitting the noise structure borne. Anyone curious about this can just unscrew their pump and suspend it with a couple of bungee cords, you will hear the difference.

Tom.B said:

Ours sounds like a quacking duck in the mater bathroom which is under the lower helm. :lol:

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Originally Posted by Keysdisease
Most pumps do not create much airborne noise

You may need to consider the distance. If the run is 30' or more you may need the bigger ap pump because of the pressure drop in the lines. A long distance between pump and rudder cylinder also raises the line pressure at the pump so that generally translates into higher running current for the pump.

The other option is mounting the pump near the rudder as mine is. That reduces line pressure, system lag/overshoot, and operating currents. You do need to use larger gauge power wire for the pump to make sure you dont drop more than a volt or so.

By the way the seastar ap pump is a good replacement for those that have the capilano setups with that crazy diverter valve gizmo. The ap pumps have 3 lines in and 2 lines out to the cylinder, it lets you plumb from the helm stations to the ap pump and then to the steering cylinder easily.

rubber mounting grommets should be good enough to keep the pump chatter from turning the boat into a speaker.

The OP has a 36ft boat and he's mounting the pump near the lower station, no worries about pressure drop.

The reason there are so many comments about AP pump noise is because the rubber grommets typically found on these pumps do not provide adequate isolation. As in the AP pump pictured, no way those grommets are even close to being loaded equally, and so the two at the pump end are being loaded well beyond their performance capacity. Along with them being poor isolators to begin with and the typical over-tightening found in these installations = pump noise.

what_barnacles said:

You may need to consider the distance. If the run is 30' or more you may need the bigger ap pump because of the pressure drop in the lines. A long distance between pump and rudder cylinder also raises the line pressure at the pump so that generally translates into higher running current for the pump.
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rubber mounting grommets should be good enough to keep the pump chatter from turning the boat into a speaker.

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45 hours,,WOW. I would think a decent yard could install and get up to speed an entire new system of electronics in that amount of time. How much $ per hour ?

It took me 17 hours on the same size boat and this was my first attempt.

My boat mechanic #2 came through, and will advise or do the work himself, whichever I need. Along with some other owners at the marina offering advice, you guys, and my own research, I'm much more confident now.

To answer some of the above speculation, I did get the oversized pump and it'll be much less than 30' from the cylinder anyway. Noise isn't really a huge issue, in the saloon and forward cabin, adjacent to the space where I hope to mount it, the engines will be much louder anyway. But I figured I'd work in whatever noise limiting I can.

Based on the weather forecast, none of this will happen for at least another week or two anyway.