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Old 10-18-2007, 03:07 AM   #1
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I wish to install a below deck autopilot... and I'm certainly no expert.

How does one over-ride a linear drive or hydraulic ram of this sort of autopilot when connected to the rudder shaft of a mechanically steered sailboat?

Our boat is equiped with chain & cable steering. It looks to me like the drive end of them are always tied to the rudder shaft by either connecting the ram / drive to the steering quadrant or to a dedicated tiller arm mounted on the rudder shaft.

Are tee fittings used and plumbed to a ball valve in the cockpit to allow fluid to flow and bypass the hydraulic ram when hand steering?

Does an electric linear drive have a remote controlled clutch of some sort to disconnect it when hand steering?

The autopilot salesman seems to think that I'm gonna need to do away with the chain & cables and convert to hydraulic steering. I definitely don't want to do that kind of surgery.

Am I missing something?

Help me Mr Wizzard! I just want to connect a simple yet powerful below deck autopilot to my existing steering system.

Thanks.

Kirk
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Old 10-18-2007, 04:10 AM   #2
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I just completed installing my below deck hydraulic ram autopilot at the start of the summer. I will let you know that it can get quite involved in everyway...just a head's up ;-)

But, to answer your question there is a solenoid valve that acts as a clutch when the drive is not engaged. There is some fluid pressure drag, but it isn't anything that you can't get accustom to.

The autopilot salesman seems to think that I'm gonna need to do away with the chain & cables and convert to hydraulic steering.

He doesn't know what he is talking about.(assuming of course he hasn't been down to your boat)

Mine is chain and cables...it simply requires attaching a tiller arm to the rudder post with a beefy key-way. There are several companies offering tiller arms specifically for below deck hydraulic autopilot conversions....Edson is who I used. Buck-Algonquin has a few also.

The biggest expense in terms of time is in building a solid fatigue proof platform to mount the drive and ram. I used 3/4" Garolite glassed into the hull...it cost an extra $400 bucks, but I know that it will stop bullets.

I highly recommend getting linear hydraulic over linear electric drive.
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Old 10-18-2007, 04:54 AM   #3
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Hi Kirk



The key questions are:

Do you need to over ride the mechanical steering?

Would it bother you if your steering wheel turns when the auto-pilot is engaged?



I have exactly what you are trying to do. In my case, I have a large diameter wheel in the cockpit with Chain/Cable connection right to the heavy duty steering quadrant. Gives me a great feel for any rudder slop, or weather helm and is a bullet proof system in a storm. Would never change that!



The autopilot is serviced by an electric/hydraulic pump which feeds a large hydraulic ram directly coupled to a Ball-Joint affair which is bolted onto the steering quadrant.



When the Autopilot is turned on but still on standby the hydraulic pump is not running and the mechanical steering is as normal. When AP is engaged the pump instantly turns on and controls the hydraulic ram and rudder as sensed by the autopilot with the cockpit wheel moving back and forth as directed by the AP.



My inside steering has a small wheel and does use a manual hydraulic line. Normally that manual wheel pump is deactivated via a bypass solenoid on the hydraulic line and you need to push a lighted take-over button beside that helm station to activate the hydraulics and charge the steering ram. Again, the outside mechanical wheel will turn in concert with the inside helm movements.



Hope that helps
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Old 10-18-2007, 05:06 AM   #4
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One other note. As Trim rightly advises the system should be designed heavy duty for the repetitive torques of autopilot steering.

Once you are all done, do some sea trials by going astern and steering figure 8s at ever increasing speeds while inspecting and listening to your system. That is a good test for any steering system!
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Old 10-18-2007, 04:09 PM   #5
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Thanks, Guys.

So - am I to assume there are check valves inside the hydraulic pump head which allow fluid to flow whenever the pump is not running?

Simple as that?

Are all hydraulic pumps which are designed for autopilots set-up this way to allow free flow when not running?

Thanks again,

Kirk
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Old 10-18-2007, 09:12 PM   #6
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Hi Kirk,

I am undergoing a technical fact finding mission on my auto steering at the moment. My full set-up is hy-drive hydraulic, with a TMQ auto helm. The steering has always felt 'notchy', and bleeding has made no difference. It appears the TMQ bypass valve may have been installed on the wrong part of the line. I am awaiting a hydraulic steering guru to find time to look at the installation to tell me if it needs modification.

This may be of little help to you, but apparently the positioning of the bypass is critical.

David
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Old 10-18-2007, 11:21 PM   #7
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Quote:
Originally Posted by Gallivanters View Post
Thanks, Guys.

So - am I to assume there are check valves inside the hydraulic pump head which allow fluid to flow whenever the pump is not running?

Simple as that?

Are all hydraulic pumps which are designed for autopilots set-up this way to allow free flow when not running?

Thanks again,

Kirk
My system is a Raymarine Linear Hydraulic Type 3, the clutch valve is located on the end of the ram valve body.

See install manual to get an idea of what is involved:Hydraulic_Autopilot_Installation_Manual.pdf
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Old 10-19-2007, 12:17 AM   #8
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Hi Kirk,

Questions, Boat length WL --------------- ft ; your boat' displacement ...........lb ?

Type of rudder Skeg hung/spade ; - balanced ---- unbalanced .

Any idea of force required (at quadrant) to move rudder in average conditions ? (difficult question )

I have seen one on a Kong and Halvorsen 45ft stink boat - with two steering stations hydraulic ram

- no probs.

The Comnav company has a good rep, However, do they actually spell out what is the max size of sailboat the 1420 will handle? Is there an updated model to the 1420 ? Outside Canada do they have dealers ?

They do supply a very good Op/install manual for the existing model = .pdf :-

1420_Installation___Operation_Manual_V1.0.pdf
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Old 11-05-2007, 06:11 PM   #9
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I can recommend the Wagner magnetic heading hydraulic units. Installed one on my former boat, 54' 55k sloop, had it running 24/7 in a storm for almost a week that saw ten boats lost, 3 with all hands. It never missed a beat and had to deal with huge waves (from the deck they were taller than my 70ft mast in the troughs) down which we would surf at up to 18-20 knots, then slam into the back side of the wave in front, veer abit and slight roll, then get whacked on the stern quarter by the breaking sea we'd just surfed down. Then the slow climb up the face of the next following sea to repeat the process...on occasion we'd get one coming a bit crosswise to the pattern, get peaked up and fall off the crest with a resounding BOOOOOM!!!. Amazed me that the boat held together. Due entirely to the strength and speed of the Wagner we only got pooped once, did not roll or broach at any time.

Out of six crew on board, 2 were moderately 'ambulatory' (until one got 'tetherballed' by his harness from one side of the cockpit up and around then down to the otherside, the resulting injuries requiring him to go below and get stuffed securely bout the mast on the cabin sole.), 3 were immobilized by the motion, (one nearly died from dehydration,be careful). If not for the Wagner, we'd have all died, no way to handle the wheel in that kind of sea for more than a few hours. The unit my brother installed for me just before the trip was oversized for my boat, think it was rec'd for a 70 footer. Electric, wind, whatever would have been useless, for this kind of work, hydraulic was king. The wagner was recommended to us by pac northwest commercial fishermen.

seer
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Old 11-05-2007, 06:20 PM   #10
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Welcome aboard Seer. Thank you for sharing your very frightening experience with us. It is at times like that, that you are thankful for the "oversize" of the equipment that you have installed.
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Old 11-10-2007, 04:14 PM   #11
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About good autopilots and mechanical steering systems--just this week we've been in touch with WH Autopilot and AutoNav (owned by Paul Wagner) to come up with a system for our boat. We'll choose whichever works best for our situation. Both companies will work with owners for owner installation of a custom system. Both companies have excellent reputations in the world of commercial fishing in the north Pacific where a solid autopilot that works in all conditions is a key thing. We expect differences between the two proposed systems will be the variety of user interface, nav inputs, and cost.

We have a wonderful Edison Robinson double arm steering gear that is pretty much indestructible but unfortunately not exactly compatible with a hydraulic autopilot. The particular worm gear is way oversized for our boat, we're 29 T and 46' waterline with a 19 sf keel hung rudder. The particular worm gear is usually installed in boats of twice our displacement and waterline so it's "stout."

I'm writing about "our" situation because most people will tell you a worm gear precludes the use of a hydraulic pilot and most will tell you that the worm gear must be removed entirely from the boat to install the hydraulic pilot.

Its not true.

The worm gear does have to be disconnected from the rudder shaft unless one wishes to drive the rudder with autopilot using a chain and sprocket on the helm (this really slows down the responsiveness of the autopilot, takes more energy, and isn't recommended). This disconnect means that you're operating with a hydraulic steering system instead of using the worm gear. But, having the worm gear as a backup steering system is a great thing (much better than a tiller...). It gives me confidence to know that we'll have two different and reliable steering systems--the first being hydraulic and the second being the trusty worm gear if something goes wrong with the autopilot.

Having the hydraulic arm directly attached to the rudder with a keyed collar is the desired way to go if one has access to a spot on the rudder shaft to do this. This leaves the top of the rudder shaft available for an emergency tiller arm, or in our case, for reconnecting the worm gear to the rudder.

In our case (and in most wormgear cases I suspect...) the worm gear attaches to the rudder shaft with a flange that is bolted with 4 thru bolts to a flange keyed to the topmost end of the rudder shaft. The disconnect involves taking out the 4 bolts. Its possible to reconnect the worm gear by putting the bolts back in place. This will be done in an emergency by employing a collar made up with 4 aligned thru-bolts for a quick re-connect. (I could just see trying to align and insert each of those 4 bolts individually in an emergency....they'd all end up in the bilge for sure )

In our case, the rudder shaft is 2.5" diameter and 10' 1/2" long and we have 16" of open rudder shaft above the rudder bearing post (It probably has another name...but its function is bearing and alignment of the keel hung rudder.) The weight of the rudder is on a gudgeon attached to the keel. The weight of the worm gear is taken by attachment to the hull. The bearing is a 36" long tube and runs up through the hull to a point sufficiently above the water line to not have water ingress via it. This 16" access gives us plenty of room to key a collar for the hydraulic autopilot's direct connection to the rudder shaft and allows us to choose a height above the waterline that lines up with a good place to attach a steel plate to the hull to absorb the forces involved with using the hydraulic drive arm.

The chain/sprocket on the helm (that previously held an electric motor driven autopilot) will be used for a manual hydraulic pump so the helm can be used for manual steering. We also have a chart house with inside steering station--we expect to use a manual hydraulic pump in that location as well; even though both WH Autopilot and AutoNav offer handheld remotes for the purpose of manual steering via the autopilot. We like the idea of being able to do manual steering from inside. Previously, the boat had a really rinky dink mechanical system for this purpose.

We're a bit anxious about the cost of the autopilot and steering re-fit, but believe, behind the rigging, that this is the most important system on the boat.

If anyone on the forum also has a worm gear and is facing similar re-fit, please feel free to keep in touch as we go through this process. If anyone's done this or had a boat with a similar set up with worm gear, we'd love to hear about it, too.
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Old 11-10-2007, 09:40 PM   #12
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Hi RBP,

Good Post, have you got some pictures which may assist in getting answers.

Regards

Richard
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Old 11-13-2007, 03:07 AM   #13
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Quote:
Originally Posted by MMNETSEA View Post
Hi RBP,

Good Post, have you got some pictures which may assist in getting answers.

Regards

Richard
Hi,

I'll try to post a link to drawings in the next couple days. The cockpit is removed so its all open space right now--pics show nothing--but the boat plans show some of the geometry I'm talking about.

Thanks!
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