Saturday, March 4, 2017

Auto pilot

After doing some long runs of 30+ hours hand steering the boat, getting the auto pilot installed has been high on the list of projects. Finding myself in a slow period regarding work gave me the time to tackle this project, and after a few days of toil, the auto pilot is up and running.

If one were to look back in this blog for information regarding the steering system we have on board, you'd discover that it is a true hydraulic system. A hydraulic pump is driven off the cam shaft of the main engine which powers the helm sending fluid to the twin cylinder steering quadrant in the rudder room. The steering system was manufactured by HydroSlave in Rockport Main, and has been a rock solid, high performing system on our boat. I can't say anything bad about the folks at HydroSlave.

While the electronics package is fairly basic on board, it's all Garmin, and like HydroSlave, I've been extremely happy with Garmin. We have a 6212 chartplotter, and a 24" high def radar unit. So when it came time to get the auto pilot project going, I contacted HydroSlave first for mechanical input, then Garmin regarding the auto pilot.

Because the steering system is all hydraulic, I did not need to purchase a pump to power the auto pilot as I would be using the existing hydraulic pump. The only piece I would need to buy from HydroSlave was a solenoid valve which would plumb into the existing hydraulic lines. Pressure from the pump enters the solenoid valve, and signal from the auto pilot tells either the port or starboard solenoid valve which way to turn the rudder. Once the valve was mounted under the console, a quick trip to the local hydraulic shop for some fittings and to have a few short lines made up, was all it took to get the valve operational. The issue with the solenoid valve is that it restricts the flow of oil and as a result, the oil is going to heat up...more on that later.

The Garmin auto I purchased consists of the helm display, CCU device, ECU device, and rudder feedback sensor. The CCU is what tells the boat what the boat is doing in regards to compass direction, pitch, and roll. The ECU is the power device that brings feedback from the rudder, the CCU, and provides a source of power, and interfaces with the chartplotter. The rudder feedback device senses what the rudder is doing and sends signal to the ECU. The helm display is the screen one sees, and allows the user to control the system.

Installation of the auto pilot itself was pretty straight forward but it did take a couple of days. Careful attention regarding where to install the CCU was critical, and a hand held compass needed to be used to assure magnetic interference did not occur...kind of hard to do on a steel boat. The spot I chose was directly under the helm in the sink base cabinet in the master cabin. This location fit all of Garmin's parameters being low in the boat on the center line and slightly forward. The CCU was also mounted forward facing, and level with the water line of the boat. Having the CCU in all these orientations makes setting the auto pilot up during sea trial much easier. The ECU mounted under the helm console where the chart plotter gear resides. None of the cables feeding this gear can be cut, so all cables get rolled up and secured to the forward bulkhead. The existing NMEA backbone was increased by two more fittings to add the auto pilot ( the NMEA is a fantastic electric connection and makes adding hardware idiot proof ).

Not having a proper shop anymore makes fabricating parts challenging. Needing to fabricate a bracket for the rudder feedback proved to be a bit frustrating, and my first attempt didn't go so well as I messed up the geometry and the sensor didn't follow the rudder correctly. I finally got it right, and while not a thing of  beauty, the sensor works correctly and is about as tight to the rudder as I could get it. My biggest concern with the feedback sensor location is that someone is going to use it as handle while moving around the rudder room, and damage it. I'll have to think about this problem some more.

With all the components in place it was now time to connect the power cable do the dock side wizard.  The dockside wizard basically makes sure the rudder is moving in the right direction  and communicating with the auto pilot. Because of having a hydraulic steering system, when the auto pilot helm control is used to move the rudder, the helm wheel does not move. Just to make sure everything was moving and moving in the correct direction, I had to walk back to the rudder room a few times to verify. Amazingly everything worked correctly the first time. I will say it was pretty cool being able to move the rudder with buttons, and little details like a green line on the screen following the rudder to starboard along with a red line following it to port made me smile.

With the dock side wizard complete, it was time for the sea trial wizard, and a week later, I headed out into the river to clear windless day.  Once in a wide area of the river with deep enough water far enough off of the Okeechobee Waterway, I engaged the sea trial wizard. At an idle speed I began by turning the boat in a tight circle twice. While doing this, I was watching the status screen, and at the end of the second circle, the screen showed 100% compass calibration, and it was time for step two. Re positioning the boat so I had decent room for error, I brought the boat up to cruising speed and began step two. The auto pilot took over at this point and steered the boat in 15 zig zag maneuvers. This step took three or five minutes, and after a short while the system showed 100% complete, so step #3 was ordered up. Step 3 consisted of choosing a heading and engaging the auto pilot. The auto pilot again took over, and after 45 seconds, step three was completed and the system told me the sea trial wizard was complete, and the auto pilot was ready for use.

The rest of the afternoon was spent playing around by following short courses and headings just to get the feel for the auto pilot potential and basic operations. If I put in a heading the auto pilot follows it...which is it's basic function. If I plot a course on the chart plotter, with multiple turns, the auto pilot follows the course and performs the turns. As we navigate around water ways, the chart plotter lays down a trail showing where we've been. The auto pilot, if engaged, will follow those trails if I choose to do so. So if we come into a strange anchorage during the daylight hours, and want to leave during dark hours, we can engage the auto pilot to head out following the trail in as we idle away from our anchorage.

Heading  back to the harbor later that afternoon, I used the auto pilot to hold to headings and sat back admiring this fine addition to the boat. If one were to listen closely, the only noise you hear is the slight clicking of solenoid valve magnets engaging. For all practical purposes the auto pilot operates silently, and because the wheel doesn't move, it's as if a ghost is steering the boat. The folks at HydroSlave had warned me that because of adding the solenoid valve and it's restrictive configuration of how the oil must now flow, the oil was going to heat up. I have a thermometer in my hydraulic reservoir, and one of my engine room checks found the oil temperature pushing 160 degrees. HydroSlave wants  the oil temperature at140 degrees or less, so I'm going to have to find a way to cool the oil.

With it's large rudder, almost full length deep keel, and our commercial hydraulic steering system, our boat tracks straight as string and is very easy to steer.  The addition of this auto pilot is going to make a good system even better, and I have a feeling this is going to be one of those devices I'll soon be saying " I can't believe I went all this time without it". I have a 20 hour passage planned for in about six weeks, so I'm big time happy this system is up and running, and I'm looking forward to a few day trips in the mean time to make sure all is well.



  1. Conall,
    Try an inline oil cooler.

    Bill Kelleher

  2. Hi Bill,

    I'll be writing about the solution shortly... keel cooled and dry exhaust... so no pump bringing water onto the boat.