Raymarine EV-100 Power Autopilot
There are many features of my True Grit I really like. But the three I would absolutely never give up are the shower, the refrigerator and the autopilot. On a slow boat like mine an autopilot is priceless. It helps eliminate much of the grunt work of long runs and provides a far more relaxed cruise. I can sit at the helm with a book or magazine and not have to worry about maintaining a course. I just watch for traffic and it does the rest.
The initial build included a Raymarine S1000 autopilot. At the time this unit was the only one available in my price range at about $900. I dearly wanted an autopilot but just could not bring myself to spend $2,500 to $4,000 on the more common units. The lower price of the unit was possible because it used the NMEA 0183 output signal from a GPS to establish the heading. This eliminated the expensive fluxgate compass as the heading sensor. Also, the hydraulic pump was smaller and the entire system was rated for no larger than 25' boats.
Although I was oversized the system worked reasonably well and tracked a heading or route activated in the GPS. For my situation though, there are some limitations that tended to annoy me. In calm water it functioned perfectly but when things roughened either by wind or other boat's wakes I found it less acceptable. First, when the boat starts rocking the heading indication of the GPS starts to swing from side to side. This is the fault of the GPS not the autopilot. BUT the pilot is using this output and then starts trying to correct for changes that are not actually happening. These heading corrections are actually very slight and didn't really change the boat's direct much but with each rock the pump would hit for about a second on each side of the roll. The trouble is the pump is VERY loud and the constant cranking quickly becomes very annoying.
This problem is made much worse because the True Grit's interior is so quiet. If the unit was mounted in a open cockpit boat the noise would be lost among the sound of the wind, motor and water. But inside Seaquinn, even though it was mounted behind an access panel which is behind the hanging clothes locker, the pump noise just aggravated me to no end. I had a goal to make the saloon as quiet as possible and had actually exceeded my expectations but then there was this pump grinding back and forth. I usually would just give up and shut it off but that defeated the entire reason for having it.
But a few years have made a big difference in the design of autopilots. With the advancement of cell phones and Radio Controlled Aircraft (drones) using solid state directional sensors and gyros the electronics driving autopilots are changing. I bought a Raymarine EV-100 Power autopilot that features a 9-axis sensor that monitors vessel motion in all three dimensions. As per the brochure it provides - Precision monitoring of heading, pitch, roll, and yaw allowing the autopilot to evolve instantly as sea conditions and vessel dynamics change. WOW - sounds like magic! (we will see) The idea is it dampens the motion caused by rough water and provides a dampened and truer heading.
Also, because the heading sensor is not a GPS antenna it can be mounted without a clear view of the sky. In fact, they recommend placement in the center of the hull and as low as possible. The reasoning is when low the rocking movement should be greatly reduced as compared to higher on the hull. Although I couldn't get it midship I did placed in very low in the in the hull below the berth floor.
The autopilot was a more involved installation. There is the control/display unit in the instrument panel, the Actuator Control Unit (electronic brain) on a bulkhead, the heading sensor below deck, the network cables to connect the three, a new hydraulic pump and connection of the hydraulic lines. I was able to just disconnect the lines from the old pump and with just one additional fitting re-attach to the new pump. I did decided to orient the pump differently and as a result had to fabricate a new mounting block. Also, because of the new pump and opening of the oil lines, the system needed to be bled. This is not one of my favorite jobs as you are working with open containers of oil in the saloon. The result of one misstep could be a major mess. On the True Grit I can't see the hydraulic cylinder on the O/B from the helm so this becomes a two man job or in other words another test of my marriage. But no problems arose and the install and bleeding went smooth.