Installing hydraulic AP with chain/cable steering

[exMaggieDrum]

I've spent the last three hours doing searches on the forum and online for answers to these questions. I have cable/chain steering to a rudder quadrant. I will be installing a Simrad Nac-3 AP computer with a Kobelt(ex-Accusteer) HRP100 reversible pump, and a Hynautic ram balanced cylinder.

The pump manual is pretty small and doesn't give me the answer to my issue - do I need a hydraulic bypass valve for when I want to use the manual cable steering or not, or to use the windvane pilot?

The pump manual says "In the non-running position the spring operated check valves remain closed, isolating the pump from the steering system. The spring action of the check valves holds the lockvalve spool in the mid-closed position." That seems to me to say it locks the flow of the hydraulic fluid thereby locking the cylinder in place but I am not a hydraulic expert (or any other kind either).

My previous boat had Hynautic hydraulic steering at the wheel which was no problem using the AP pump since it was all teed in to the same lines. However, when I wanted to use the Monitor windvane pilot I had to manually open a bypass valve so the wind pilot could steer the boat at the wheel. I don't have a schematic of how it was all put together and don't remember after so many years since I sold her. It was a PITA to pull the bypass cable at the same time as engaging the wind pilot and v.v. to go back to hydraulic. It was plumbed in between the two lines to the cylinder so when open the fluid would circulate between both sides of the cylinder to prevent back pressure.

If I do need a bypass valve I think it would need be electrically energized so I don't have to pull a relief cable manually. I would also not want it to need power when I am manually steering (or on my Hydrovane wind pilot with the steering wheel locked at the helm). I also would be concerned about the extra electric power needed on top of the AP.

Any ideas?

[evm1024]

I'm not up to speed on your specific system but I am working on mine at the moment and hope this info will be useful.

Many pumps have a bypass solenoid (or checkvalves like yours?) that when the pump is not energized allow the hydraulic fluid to flow freely through the pump assemble.

This prevents the ram from "locking up" when the AP is not engaged. The fluid from the ram runs through the lines and to the pump and through the bypass solenoid (or check valves). When engaged the fluid does not bypass and the pump then drives the RAM.

In my system I have a solenoid on the pump. The normal state is bypass so steering is possible. When the relay is energized the pump can drive the ram.

My system also has a manual bypass valve right at the ram. This is normally closed and thus the fluid heads to the pump. But should there be a failure of the solenoid you can open the valve which allows fluid to recirculate directly in the ram. To visualize think of an H where the top legs go to the pump, the bottom legs go to the ram and the bar in the middle is the valve.

The end results is that with the valve closed the fluid travels from the ram to the pump and back (25' or 30' or so) with some degree of resistance. With the valve open the fluid only travels 2 feet. You can feel much less resistance at the helm.

Also, I have a wheel pilot as a backup. Should the main AP fail I would open the valve and thus the wheel pilot would see less resistance.

Regards

[smac999]

normally you would use a pump that would have a clutch. 2 extra wires. and the pilot would have a clutch output terminal. to engage the pump when the pilot is turned on.

but if you are running a normal pump to a piston, it likely won't have a clutch input.


looks like simrad calls it a drive engage on the nac 3. raymarine calls it a clutch.

[exMaggieDrum]

Thanks to both of you for your comments. The plot has thickened, as it usually does, with every new project on the boat. I am struggling to learn more (but doing it) about hydraulic systems in general and my equipment in particular.

I have asked SeaStar Solutions for a recommendation for a properly sized and outfitted cylinder. They have a form you fill out and send in for their engineer to review and then give the recommendation. This has been going on since Easter. The engineer had vacation over Easter and then had to address a backlog so that was a little bit of a delay.

Then I got an email from the engineer with the hydraulic schematic for my Accu-Steer HRP100-12 pump. Furuno's pumps are the same family although the HRP100 is hard to find. Kobelt in Canada took over Accu-Steer and they have not been responsive to emails about the pump. The SeaStar engineer said that this pump (and many like it) will automatically block flow through it when it is not in operation. He implied that I should be able to read the schematic and must have missed something. He said it does not default to open when off.

So I am trying to get smarter about hydraulics and schematics (just for general purposes and my own curiosity). The pump manual and schematic is here:
http://www.accu-steer.com/pdfs/HRP100Manual-Web.pdf

This schematic is for the internal valves in the pump.

It does not have a clutch like some pumps. I have found many opinions that pump clutches are a common point of failure for AP pumps but can't debate that point. I do believe I am going to have to put in a manual or solenoid driven bypass valve. I think the solenoid could be driven by the clutch output on the AP computer but will have to find a solenoid. I think a normally open solenoid valve would be best so that it would default to manual steering if the AP was off or failed. I am thinking I might put in a backup manual valve if the solenoid failed in closed position. I always want manual steerage available.

I found an excellent general overview on AP and helm steering hydraulic systems for boats here: www.sbmar.com/articles/marine-hydraulic-steering-systems/

Trying to learn more about hydraulics I found a good link which some might find interesting if are mechanical geeks like me. I found this article about reading schematics - attached below.

I'd welcome more comments. In any case I will post on my final design.

[Cheechako]

I had a B&G hydraulic AP on my catamaran. I installed the Alpha Autopilot quadrant disconnect. (Morse Cable disconnect) That system completely takes the AP out of the system when not being used.

[evm1024]

OK, I got a look at the manual and can make some observations.

The manual and the pump is for hydraulic steering. That is to say that the steering wheel turns a hydraulic (manual) pump which goes to the ram as the sole means of steering (no cables).

This AP and its pump are Tee'd into the hydraulic steering lines.

A key inthe pump diagram are check-valves 7 and 8. When the pump is off both check valves are closed and isolate the pump from the hydraulic system. This allows the manual steering pump to control the rudder.

When the pump is operating the pressure on the driven side opens the respective check valve and fluid flows to the ram. The return fluid from the other side of the ram goes to the check valve on the other line and is allowed to flow through it because the two check valves (7 and 8) are ganged together. Open one and the other is opened. This allows fluid to return to the oil reservoir (through the respective check valve #4).

What all this means it that this AP pump cannot work with a chain/cable steering system unless some sort of bypass valve is installed.

As noted in my post abobe on my boat there is a manual bypass valve at the ram and a solenoid bypass valve at the pump. I currently have an old Navico pump which is an octopus LAR type re-branded. ( Linear Drive Family | Octopus Autopilot Drive Systems )

See the photo for the at RAM bypass

[exMaggieDrum]

Originally Posted by Cheechako

I had a B&G hydraulic AP on my catamaran. I installed the Alpha Autopilot quadrant disconnect. (Morse Cable disconnect) That system completely takes the AP out of the system when not being used.

I had forgotten about this disconnect. I actually saw one somewhere many years ago. It looks pretty lightweight to me and I really don't want one more thing that could bind up or break. I'm looking to make everything very robust. I may be too paranoid about it but I would be far more comfortable with a solid tiller arm.

Alpha Marine Systems - Spectra General Information

[exMaggieDrum]

Originally Posted by evm1024

OK, I got a look at the manual and can make some observations.

The manual and the pump is for hydraulic steering. That is to say that the steering wheel turns a hydraulic (manual) pump which goes to the ram as the sole means of steering (no cables).

This AP and its pump are Tee'd into the hydraulic steering lines.

A key inthe pump diagram are check-valves 7 and 8. When the pump is off both check valves are closed and isolate the pump from the hydraulic system. This allows the manual steering pump to control the rudder.

When the pump is operating the pressure on the driven side opens the respective check valve and fluid flows to the ram. The return fluid from the other side of the ram goes to the check valve on the other line and is allowed to flow through it because the two check valves (7 and 8) are ganged together. Open one and the other is opened. This allows fluid to return to the oil reservoir (through the respective check valve #4).

What all this means it that this AP pump cannot work with a chain/cable steering system unless some sort of bypass valve is installed.

As noted in my post abobe on my boat there is a manual bypass valve at the ram and a solenoid bypass valve at the pump. I currently have an old Navico pump which is an octopus LAR type re-branded. ( Linear Drive Family | Octopus Autopilot Drive Systems )

See the photo for the at RAM bypass

I came to the same conclusions after my brief intro to hydraulics (all about pilot control of check valves, etc.). The bypass you show in the pic looks identical to the one I had on Maggie Drum except that there was a cable which led to the cockpit to open and close it. My Hynautic helm pump must have had the same check valves as my pump so the bypass was required with or without the AP pump.

Spec'ing a 12v solenoid bypass is not going so well so I may have to just go with a manual valve. I'll have "easy" access to it in a lazerette right at the helm or I'll rig a cable if need be.

Any ideas on solenoid driven valves would be great. And it would be great if the engineer at SeaStar were to give me his recommendation on a cylinder.

Thanks for your photo and comments.

[evm1024]

Yes I expect that a hydraulic steering pump would have the same (in function at least) check valves. Great minds and all that.

For myself I was going to rebuild the existing pump (with the existing bypass valve)and go with that but on further thought I think that I will just buy a new pump that includes a new bypass valve.

The Octopus pumps run less than $900 discount (I saw $825). Be done with it and sell the old pump as-is.

Could you do the same?

One of the reasons I was choosing the octopus pumps is because they OEM for other vendors. The original AP on my boat is a Navico PH8000 which uses a Octopus pump.

http://octopusdrives.com/sites/defau...ng%20Pumps.pdf

[Matt Johnson]

Originally Posted by evm1024

My system also has a manual bypass valve right at the ram. This is normally closed and thus the fluid heads to the pump. But should there be a failure of the solenoid you can open the valve which allows fluid to recirculate directly in the ram. To visualize think of an H where the top legs go to the pump, the bottom legs go to the ram and the bar in the middle is the valve.

I know Parker offers them with a manifold..... but for simple and cheap, instead of the manual valve, couldn't you replace this with a simple solenoid valve?

Matt

[Cheechako]

Originally Posted by exMaggieDrum

I had forgotten about this disconnect. I actually saw one somewhere many years ago. It looks pretty lightweight to me and I really don't want one more thing that could bind up or break. I'm looking to make everything very robust. I may be too paranoid about it but I would be far more comfortable with a solid tiller arm.

Alpha Marine Systems - Spectra General Information

Yeh, it's pretty robust, but one more link in the chain I suppose. I didnt want to be working my hydraulic cylinder all the time. I had the Alpha Pilot on 3 boats prior and liked them.

[exMaggieDrum]

Originally Posted by evm1024

Yes I expect that a hydraulic steering pump would have the same (in function at least) check valves. Great minds and all that.

For myself I was going to rebuild the existing pump (with the existing bypass valve)and go with that but on further thought I think that I will just buy a new pump that includes a new bypass valve.

The Octopus pumps run less than $900 discount (I saw $825). Be done with it and sell the old pump as-is.

Could you do the same?

One of the reasons I was choosing the octopus pumps is because they OEM for other vendors. The original AP on my boat is a Navico PH8000 which uses a Octopus pump.

http://octopusdrives.com/sites/defau...ng%20Pumps.pdf

Great comments from all. The link came back with a 404 error but I found this:
http://octopusdrives.com/sites/defau...20Brochure.pdf

I will consider Octopus after the comments here. I had looked at them last year but for some reason took them off the list. Memory fails me on why. I selected the Accu-Steer partially based on what a friend had installed on his Tayana 42 with the same cylinder I was looking at. HRP100-12 pump and HRP100 pump (hard to find now since Kobelt took over but I am a "lucky" owner of a new one).

Of course the plot has thickened. I got a reply from the SeaStar engineer. BTW - they have been great. He hasn't given me the easy answer I wanted since he told me it wasn't possible. My pump would work with my cylinder, but would not with a smaller bore cylinder. It has a max 500psi working pressure which could only work with the larger bore size.

But a cylinder with a 1/2" clevis ball end would have to be less than 2". I wanted a smaller end to work with the (expensive) Edson Marine tiller arm. Most all readily available AP pumps (Furuno - actually Accu-Steer but smaller, Simrad, Raymarine, and Octopus) are rated at 1000psi. Although I am chasing down the rating for the Octopus, I think it will be the same.

Octopus offers two types of reversing pumps - gear and piston style. The gear pump is quieter but the piston pump is more precise and more powerful. Two features I like are the built in shutoff valves, and more important, the availability of the electric solenoid bypass valve. Such as the example you provide the photo of. I haven't priced the combo yet.

So it looks like I could still use the Hynautic cylinder I have with the pump I have. They are strong and robust with great reliability from all reports. The cons of the cylinder are its size and weight and the size of the ball end.

I will ask Edson (also great tech support) about whether I could use a top or bottom clevis bored to 3/4", which they will do for an additional fee or I could do it. The normal fit of a ball end to their arm is in between a bracket on the working end. I thought the Edson arm was over the top expensive until I priced the HD Buck Algonquin arms. They are all expensive although I can get a lighter duty with less robust mounting bolts for less.

And I thought the installation was the only hard part left to do! This is way too important to try to go cheap on this. I view it as the most critical upgrade I will do for my boat to go offshore, along with the windvane pilot of course. I want it done right with the right parts.

Steve - thanks for the recommendation on the Alpha tiller arms. Your experience with several boats with them speak well to their use and reliability. I am still going with a bypass, either electric or manual.

I think it would still be a good idea to have a manual backup bypass, in addition to an electric solenoid bypass, in case the electric one fails for whatever reason. It would be in parallel with the hydraulic tubing to the cylinder between the electric bypass or pump bypass. I could manually open it and take the pump out of the circuit so I could manually steer.

What I think is strange is that I have found zero comments on any autopilot/pump provider information addressing combination manual and AP steering. They all assume you will be adding an AP into an existing hydraulic helm system. So there is not discussion of bypass valves, at least that I have found so far.

[exMaggieDrum]

A remaining issue, as if there weren't enough already, is concerning a reservoir for the pump. Tieing in an AP pump to a helm steering system, either the helm pump serves as the reservoir, or (like my previous boat) you have to have a separate reservoir in addition to the helm pump. My previous system had a Hynautic pressurized reservoir which seems like overkill as it would be much bigger than would be needed in addition to being another half a boat buck. It also has to be above the pump and cylinder, which given its size, would be nearly impossible on my boat.

So the next issue is what I need and can fit for a reservoir. What are you guys using? Comments?