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Autopilot Install Finish

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They say better late then never and here it goes.

It has been over two years since I finished the Autopilot install and I couldn’t be happier. The Simrad AC12 steers the boat beautifully and has made cruising a breeze.  Last year we did a two week cruise to Maine with some long delivery days where we barely touched the helm.

My last entry on the install showed completion of the rudder position sensor.  After the sensor was installed the next step was to get into the wiring.  Using NMEA2000/Simnet on the compass and the rudder sensor simplified the wiring.

The RC42 compass was installed low in the boat, under a settee close to mast.  Basically as close to the center of balance as possible.  This gives the RC42 a truthful picture of how the boat is moving without exaggerations that can cause overcorrections.

I installed the AC12 and wiring hub in the port lazarette on the aftmost bulkhead.  This simplified the wiring as it is just a few feet from the drive and NMEA2000 drops from the rudder sensor, helm mounted chart plotter and Simrad Gs25 mounted on the stern rail.  The AP24 was mounted in an existing pod at the binnacle.  It replaced an old Raymarine st4000 head with a similar cutout size.  I used the old wiring coming out to fish the new wiring coming in.  Using Simnet it was a single wire run.  I also reused the power line from the St4000 as well which speeded up the new wiring install.  The boat already had a dedicated breaker on the main electrical panel for an AP.

I have had a few comments asking for more photos of the sensor and drive install.  I will try not to disappoint with what is below.  I want to grab a few videos of the AP in action.

 

 

 

 

Below Decks Autopilot DIY Part 5 (of many)

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Sorry for the delay but now time to finish this.

With the hole drilled for the arm bolt and the drive mounted the next step is the rudder position sensor (Simrad RF25 NMEA 2000 sensor).  I scoured the net for reference photos and saw a few where the position sensor arm used the steering quadrant as an attachment point.  After an hour study in the aft lazarette I could see no way to make that work.  I decided to use the tiller arm as the attachment point and build a custom base to support the sensor body.  It sits right next to the rudder shaft parallel to the beam.

I used some plywood scraps and a 4″ square piece of box aluminum (ebay) to make the platform and riser.  I tucked it in as tight as possible to the rudder shaft so the Sabre quadrant/steering covers would not interfere.  I also made it easily removable from the base in case the steering stuffing box needs servicing.  The base is epoxied to the hull with a few layers of fiberglass cloth.

I attached the other end of the sensor to the tiller arm using the threaded rod attached to a small stainless L bracket, screwed (drilled tapped first) into the tiller arm.  I don’t have any good pictures of this.

Rudder position sensor mount fabricated from plywood and epoxy.

Rudder position sensor mount fabricated from plywood and epoxy.

Sensor and stand being put on the base. The sensor can be easily removed for service.

Sensor and stand being put on the base. The sensor can be easily removed for service.

Autopilot Install Finish

 

 

 

Below Decks Autopilot DIY Part 4 (of many)

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Drill Baby Drill!

At the end of part 3 I had started the drilling process. The Edson tiller arm can lock to the shaft in one of three ways: key, set screws or through bolt. For a hollow pipe rudder shaft I would think a through bolt is the easiest to deal with. A key will require an existing keyway or some machining work on the shaft (that will need to be removed from the boat). The through bolt is probably easier then set screws which would require drill/tapping two holes. I went with through bolt but your mileage may vary.

After I drilled through the outside in I chucked a 10″ 3/8 bit (Black Oxide) and started going at it. I used tape on the bit to gauge my progress. With lots of pressure I got through it in about 20 minutes. I pulled the bit every few minutes to clean the shavings. I could tell when I crossed from the stainless steel shaft to the bronze arm as the drilling got smoother and quieter. Never had any issues with overheating.

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Starting with the long 3/8″ bit

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Victory!

Rudder Stop Modification

After getting the tiller arm attached I started working on rudder stop modification.  The rudder travel cannot exceed the drive travel or else the drive can be destroyed.  I hooked up the drive to the tiller and and moved it by hand to see where the drive stops are.  I then measured the distance to the rudder stops using drill bits as feeler gauges.  I then added 1/4″ as shock protection.

The rudder stop on the Sabre 36 is a piece of steel angle with rubber blocks.  To move the stops I shimmed up the rubber blocks using King Starboard blocks that ripped on the table saw.  I used two 1/2″ pieces to get to 5/8″ and 7/8″ on the rudder stops.  I wound needing a second attempt to add another 1/8″ to be sure even under hard shock load that the drive limit would not be tested.  Better safe then sorry.

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Bump stops moved out using black starboard

Below Decks Autopilot DIY Part 5 (of many)

Below Decks Autopilot DIY Part 3 (of many)

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I am making some good progress on the project.  Over the past few days I have the drive aligned and the mounting foot bolted in. I threw together the wiring with temporary rudder sensor configuration and was able to successfully complete the Simrad autopilot installation program and drive test.  Everything is looking good.  Below are some notes for the alignment phase.

Drive Alignment:

The idea is to get things aligned so the drive is at the mid-way point when the rudder is perfectly centered.  Using a tape measure I hand centered the piston.  The Raymarine type 1 has 12″ throw so I set it at 6″ (as close as could).  I also unscrewed the drive end a few turns so it could either way for fine tune adjustment.  I then centered the rudder and noted that my tape mark on the top spoke of the wheel (helm) was centered as well with the spoke perfectly horizontal.

I connected the drive to the tiller arm and set the mounting foot on the base.  Did some alignment checks with a square and level to make sure everything looked ok.  I then drilled two holes through the foot and bolted it down with two SS 3/8 – 16 hex bolts.  I then checked center position by turn the wheel gently to the drive stop port and starboard and using a tape measure to check the height of what was the center spoke above the deck with the goal of identical measurements on either side (~23″ for a Sabre 36 with a 36″ destroyer wheel).  It required some tweaking and I wound up with a second set of mounting holes as I initially had the drive too far towards the center line.

Once I had everything aligned I rigged up the rudder sensor and ran through the calibration and alignment.  This will also show any inconsistencies with alignment.  The rudder sensor calibration should show consistent angles after setting one side.  During the rudder drive test everything sounded nice and smooth.  I then finished bolting down the foot with all four bolts.

During this phase I also measured for rudder bump stop modification.  The stops cannot let the drive exceed it’s limits which is 35 degrees on either side (assuming 10″ radius arm). The Sabre 36 factory setting is around 40+ degrees.  I gently pulled the tiller arm to the drive limit and then measured the gap.  In measuring I found out the  rudder  stop bar was a bit misaligned so one side needs a 5/8″ extension and the other a 3/8″.  I used drill bits like big feeler gauges to help measure  the gap.  I will post some pics of the bar and modifications next post.  I removed the bar to work on it off the boat in the garage.

I had some more time so I started drilling the 3/8″ hole through the rudder shaft and the long side of the tiller arm.  I used smaller bits to drill a pilot hole and it only took about 15 minutes to get through back side.  I am now working with a 10″ 3/8 bit to get through the far side and progress is slower.  I used WD40 as cutting fluid as it is easy to spray into the deep hole with the little straw.

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Below Decks Autopilot DIY Part 4 (of many)

Link

Sabre Sailboat Yahoo Group

BTW – For those interested in Sabre Sailboats, please check the yahoo group.  I noticed that yahoo does a terrible job with SEO for their groups and it doesn’t really show up in a Google search for Sabre Sailboats.  There is an active community along with a rich archive of messages, photos and files that covers everything you want to know about Sabre Sailboats.  

Below Decks Autopilot DIY Part 2 (of many)

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Project List

This project has many facets.  My posts may bounce around a bit but here is the list of specific sub-projects:

  1. Build/install platform for drive.
  2. Install tiller arm on rudder shaft
  3. Align and install drive
  4. Modify rudder stops for 35 degrees
  5. Install rudder reference sensor
  6. Install autopilot control head in binnacle pod (will replace old ST4000).
  7. Install autopilot computer + power
  8. Install compass
  9. Wire up everything (head, compass, reference sensor, computer) on the NMEA2000 bus
  10. Modify below deck steering system cover to fit over ram

This is not a project for the meek.  From what I understand pros could charge up to $5K labor for this type of job.  There is quite a bit of custom fabrication.

Drive Selection and Installation

If you have a typical quadrant/cable steered boat then you will probably need a linear drive and tiller arm.  There are some quadrants designed to have linear drive attached but my Edson quadrant is definitely not one of these.  It is aluminum and not designed to be subject to point load forces from a ram.

There are a few choices in autopilot tiller arms.  I decided to go with the Edson bronze arm.  It is not cheap but it is one fine piece of bronze alloy.  Edson will custom bore it for the rudder shaft diameter.  The Sabre 36 factory spec for my boat is 3.475″.  I used a micrometer to double check and found it to be within .003″ at the top so I went with the factory spec.  It fits perfectly.  Required a twist to work it on and snugs together when the clamp bolts are tightened.

One fine piece of bronze

One fine piece of bronze.  Took about a week to get from Edson.  Because I have hollow rudder shaft and no keyway I went with the through bolt.

Test fit over the top of the rudder shaft. Should be perfectly snug

Test fit over the top of the rudder shaft. Should be perfectly snug with no gaps when clamp bolts are tightened

For the linear drive I choose a Raymarine Type 1 Linear drive.  When shopping around you have options for hydraulic and mechanical drives.  I went with the Raymarine Mechanical for a number of reasons: low power consumption, widespread usage, flexible mounting options and flexible installation tolerances.  It also has a decent manual.

Raymarine Type 1 in the box

Raymarine Type 1 in the box

I wanted to tackle the drive install first.  The Sabre 36 has a fairly cavernous area aft of the helm.  I can lower myself completely into the lazarette and get good access to the rudder shaft and the mounting surfaces.   I spent some time in there visualizing the work and decided to install the drive on the port side, perpendicular to the center line.  The arm will be installed facing forward.  The drive will be mounted to a wedge tabbed into the hull.

The first step was to attach the tiller arm and get it on centerline.  I then clamped a 48″ level to it and worked on determining the wedge location.  I accounted for the height difference between the drive mounting foot and drive end using some blocks of wood between the level and arm.  For distance I used the mid-position measurement from the drive manual.  I used a sharpie to start marking:

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Marking Locations

After the measuring was complete.  I did some scribing and built a wedge shaped platform using 1/2″ meranti marine ply.   This will be built up and tabbed in with west system and glass cloth.

Dry fitting everything

Dry fitting everything

Trying to keep the drive mid-extension for final dry fitting.

Trying to keep the drive mid-extension for final dry fitting.

Finally I was ready to start thinking about adhesion.  I decided first to install a mini-stringer to give the platform more attachment surface and stiffness.  The old paint and surface roughed up with a Multi-master and carbide grinding tip.

Stripping paint and roughing up the glass. Using a vacuum to minimize dust in the boat.

Stripping paint and roughing up the glass. Using a vacuum to minimize dust in the boat.

Mini string epoxied in with first layer of tabbing

Mini stringer epoxied in with first layer of tabbing

Platform bonded to hull plus 4 #10 screws into stringer. More tabbing coming soon

Platform bonded to hull plus 4 #10 screws into stringer. More tabbing coming soon.  Inside has been stiffened with a layer of cloth and west system before installation.

All bonding with done with West System and High Density bonding filler.  All tabbing done with no fillers.

Below Decks Autopilot DIY Part 3 (of many)