Hunter 41DS auto-pilot 'brain' install location and other questions

[MFD]

ueHi All,
I have a ~2009 Hunter 41DS and it is time to do a thorough inspection of the binnacle, steering system, autopilot and similar things other than dropping the rudder.

I have the 2-cabin model, and the autopilot control/display head is an ST7002. I know from inspections some time ago while offshore that I have a RayMarine 'type 2' linear drive - which disturbingly enough was leaking tiny bits of what looked like maybe mineral oil or similar after a few days of very heavy exercise.

By and large happy with the system the way it is (I am second owner of the boat), meanwhile it's been on the backlog and finally made it up the list for review this winter. Hooray!

Q1: Does anybody know where the 'brain control' unit installed? The ram/linear-drive is easily accessible from inside the port side of the aft cabin, has a wiring block. I was expecting to find it somewhere in the largish port-side lazarette space. I have had the top instrument area off in the past near the wheel, but never below that. I presume it is in the lower enclosure there?

Q2: I noticed again two vents/hose areas underneath what I call the little 'clamshell' fiberglass section that is from the binnacle back to the swim step. From eyeballing below, with flashlight, mirror on a stick with a light, it was not totally clear to me where those hoses ran. Other than it appeared that they BOTH ran to the cockpit manual bilge pump.


Will post some pics later today or maybe tomorrow to better clarify, and also more as I do inspection.

Thanks for the help!


Edit - Adding some pics and and more question #3

Q3: The aft end of the little 'clam shell' fiberglass place around the helm area seems to have weak supports, at least on my boat. I am going to investigate how far through the gelcoat cracks go and also it seems it would have been more sensible for original build to simply put in neoprene gaskets to spread the load across the entire weight/edge area?

 

[Rjm st.petersburg]

On my 2005 41DS the Autopilot brain is located at the Nav station, behind the panelling on the left of the electrical panel. The panel is only held in by clips.
The hoses on the starboard side compartment of the swim platform are for the aft AC and propane venting.

 

[MFD]

On my 2005 41DS the Autopilot brain is located at the Nav station, behind the panelling on the left of the electrical panel. The panel is only held in by clips.
The hoses on the starboard side compartment of the swim platform are for the aft AC and propane venting.

I just updated my original post with some pics, the two below steering deck hose entries are on the port side on my boat.

Also - for propane leakage, to the best of my knowledge it needs to be direct 'down/gravity', where as the two I posted in one of the pics are above the locker itself?

 

[Rjm st.petersburg]

Mine are definitely on the starboard side and labeled with a warning on the thru Hull to leave open for the propane. The other is from the AC I traced back to the aft AC before I ran Barnacle Buster through the system. My boat is a few years older than yours is.

 

[ice breaker]

Those are bilge pump exits. One is for the manual pump, the other is attached to the hi water 2nd bilge pump.

 

[Rjm st.petersburg]

Definitely not the case on my 2005 41DS. One is labeled from the factory for the propane, the other I removed to create a loop to run Barnacle Buster to clear the water cooling lines. Barnacle Buster worked very well in clearing the lines out.

 

[DRhoads]

I think you will find it near the nav station mounted vertically behind a panel. nav computers need to be vertical as much as possible. At least the older versions are that way

 

[ice breaker]

Definitely not the case on my 2005 41DS. One is labeled from the factory for the propane, the other I removed to create a loop to run Barnacle Buster to clear the water cooling lines. Barnacle Buster worked very well in clearing the lines out.

I believe that we are in total agreement. The picture above shows what is under the floor in the cockpit, not the back lazerete.
Ours are labeled too.
On our 41 the propane Vent and AC water outlet for the rear AC unit is located in the large storage area in the very back of the boat by the engine exhaust outlet just above the water line. Both are lower than where they originate so that they will drain via gravity. I understand that these configurations may have changed over time. I attached the bilge diagram from the manual for reference. The propane line absolutely needs needs to drain as propane is heaver that O2.

 

[dkinzer]

On my 2007 H41AC, the S3 Course Computer is mounted behind the forward panel at the nav station - the VHF radio is mounted on that panel. The panel is held in by clips and must be pried out. Or, you can drop down the DC panel and get your hand behind it to push it out.

The second photo shows how my S3 is mounted (the larger grey box). There are several connections to it. One is the fluxgate compass which is mounted on a stringer just under the sole near the bilge pump. Another connection is to the rudder position sensor which is located below the floor panel aft of the helm. And, of course, there are connections to the steering servo. Mine is wired so that the S3 provides the power to the SeaTalk1 network. The S3 also bridges GPS and heading data that it receives on the SeaTalk1 network to its NMEA 0183 output. In my setup, the NMEA 0183 output is connected to the VHF radio so that it gets GPS data, too for DSC and other purposes.

 

[dkinzer]

In case you weren't aware, your rudder position sensor is that device near your left foot in your second photo.

 

[DayDreamer41]

@dkinzer exactly as ours is setup as well

 

[MFD]

Hi All,
Thanks for all the replies. Finally got some time to poke around on this project again this evening. I also realized a couple days ago that I already had the autopilot docs downloaded already.

It is interesting that some of us have the autopilot linear drive installed on port and some on starboard. Still unsure if that difference is between 41AC/41DS, or the two/three cabin models. I do know that some things are slightly different between my boat than the docs that Marlow-Hunter was kind of enough to share out publicly a few years ago.

We have sprinkles of snow here in Seattle now, and after further investigating where the fitting is on the aft/port side where the 'clam shell' deck cover thing has been resting on the hull itself and the less than great screw attachment that held it in and is still supporting weight on the starboard side - I am going to need to reinforce the hull itself and not just the clamshell thing, plus deal with the cracks. All of which means warmer weather is needed!

I also realized a problem that I have had with the rudder sensor is the way it is aligned and exceeding mechanical requirements (no more than 5 degrees out of alignment) from Lewmar specs. Mine would always pop off after anything from a few days to a few months and a few years ago when in San Francisco I just gave up and put it aside. I did reinstall it a bit before this post/pics, after bending the rod a little bit to make in sort of 'Z' shaped for better mechanical alignment but it looks like I can loosen the nuts on the actual main tube that connects to the wheel and tilt that to so things are more naturally aligned. Meanwhile too cold for me to want to tackle pulling the entire pedestal so will see how it goes this winter/spring and then review when I get back to this project next summer.

So for now, going to replace the auto-pilot boot, bought a spare a couple years ago, minimal cleaning out of rusty grease where access is easy and pack in some new grease then button things back up for the winter.

I still have not found the actual 'ACU' unit for the autopilot, but my guess is that it is behind the electrical panels and I never really noticed or thought about it before when in there.

 

[JamesG161]

I still have not found the actual 'ACU' unit for the autopilot

Mine is located near the AP motor.

Jim...

 

[dkinzer]

I also realized a problem that I have had with the rudder sensor is the way it is aligned

I wondered about that although it could just be the perspective of the photo. My understanding was that the link that connects the rudder arm to the position sensor arm should be connected so that the distance from the center of rotation of each arm to the point where the link attaches should be equal. I suppose that there might be a calibration process to account for other geometries but it seems to me that there would be a sinusoidal relationship between the linear movement of the drag link and the rotary movement of the position sensor.

 

[SV Maverick]

Like others have pointed out you have to improve the geometry of the feedback arm (rudder position indicator). At an angle like it is you will have differential (more movement one way than the other) and non linear feedback. Here is a possible suggestion. In the centered position the feedback arm should be parallel to the bell crank. Hope that helps. I installed an auto pilot from scratch on my 40.5 and had to work out similar problems. What do you think?
k.

 

[dkinzer]

SV Maverick: what you have depicted is exactly how the rudder position transducer is mounted on our H41AC. When I was investigating this, I found that the "rudder neutral" indication didn't quite match the center of the rudder post's actual range of motion. I was able to adjust it so that the rudder position on the ST7002 indicated neutral when the rudder was in the center of its range.

 

[MFD]

I agree that going to the rudder arm seems more natural, and also matches the various docs I was able to find from Lewmar Raymarine last week.

Meanwhile per the Hunter docs in my post #12 above, the pics match everything else on my boat and they have installed on the tube-link thing. I guess that is called the 'rudder drag'? Another issue I noticed, even if I can get it realigned on the tube so it stays connected - the tube itself has a certain amount of rotation to it. That in turn creates a little slop in how much gets sent to the sensor.

I like the idea of just attaching it directly to the arm though. Meanwhile there could be a reason Hunter standard operating procedure is to put it on the rudder drag link tube. Like clearance to the rudder drag link at maximum angles - and that the sensor itself can not have its center aligned with the rudder center, etc.

I will do a little measuring before I button things up when the snow goes away. Gives something to mull over until the spring when I restart this project.

 

[dkinzer]

The attached image is from the Raymarine 81105 Rudder Position Sensor installation document (available on the raymarine.com site). It confirms the sketch made by SV Maverick.