Speaker to magnets

It's exactly what it looks like, a field. A neutral place generally free of magnetic sources. I say this because there is no place on earth free of magnetic fields. We all live on a giant roundish rotating magnet. But in this empty field there isn't much. On our planet ambient background magnetic fields typically vary around 25 to 65 microTeslas. The extra microTeslas on you see on the meter are largely coming from power lines and other things around me. On the whole this isn't much and the local field is reading zero. However, a large green field isn't boat by any measure, and this is where we start.

The ORB's have come, are you prepared?

This boat really was never designed to have an autopilot installed despite the fact it's a twin engined hybrid pleasure bowrider and fishing boat. I visit the boat, crawl around, snap pics to aid my creaky memory and figure it's possible. Not easy, very cramped but I can do it. It has a new Teleflex helm jammed into a tiny console, no worries there other than the lack of room. What I didn't know was something was different, very different about this helm that I think even an experienced installer like myself could easily miss. I would bet that most couldn't tell from the picture what this is, but I'm going to enlighten all. From my experience the line from the movie Groundhog Day "Anything that's different is good" was not.

Autopilot Guidance

To say the boat owner was upset was an understatement. The boat had nearly thrown himself and it's occupants into the drink. Without seeing the event I already had a good idea about what had happened, and I've been on a boat in the recent past that had done the same thing with me on board. It was scary to say the least to have the boat tipped 45 degrees on its side in a high speed turn.

I patiently listened to the story. The boat was under autopilot control and traveling around 40mph. A crab trap buoy was spotted ahead and the autopilot was disengaged. The owner steered around the  buoy and re-engaged the pilot and this is where things went awry. The boat was about 40 degrees off course, way off the course line and still traveling at about 40 kts. There are ways to mitigate this event, but not alway completely and sometimes with a small price to pay.

Here is part two of the discussion. In the news this week was the story of a former NFL player who fell overboard landing a fish in the dark while his boat was under autopilot control. The boat wasn't moving quickly but was too fast to catch. The individual was able to swim the 9 miles back to shore. He is very lucky boy. The boat was found later off Grand Bahama Island. 

Installing the Raymarine Evolution autopilot

The Evolution autopilot, from a DIY standpoint is without a doubt the easiest system to install. Virtually everything is plug and play, and in the case of this kit (part # T-70157 ) everything exclusive of the plumbing is included in the box.

The nomenclature for some of these pieces are new to Raymarine. The white and black EV1 is the sensor core. This is the computer, and heading sensor. The gray box which looks a lot like Raymarine's older course computers is the ACU-200 (Actuator Control Unit). This manages the steering actuators, and the version depends on the type of steering system your using.

The rest of these components are more familiar. The kit has a rudder reference which in my case isn't going to be used because this boat has triple 350HP Yamaha outboard engines.

Autopilot 101 DIY Part 1

Contrary to claims by some, there is no overall best auto pilot. I think all of the major brands are good, and your choice should be predicated by the characteristics of your particular vessel. The type of boat, existing or future navigation systems, accessibility and layout of the steering systems drives the best auto pilot system decision for your particular vessel. For discussions sake, we are building our auto pilot system around a hydraulically steered twin engine trawler.

You can't always get what you want, and yes we have no autopilots today.

Like the headline says, sometimes you can't easily have what you want. That being said, I say, "that there is aways a way", if you want it bad enough. So here is the problem. 

The boat in question is a Freedom 35'. It's a nice looking, and sturdy vessel, but at the preliminary "design the boat meetings", no one apparently asked the question "Would anyone want to use an autopilot on this boat?"  Or maybe during the meeting, the question was asked, and some curmudgeon at the table said, "Real sailors aren't sissy's like those power boat guys are, they love the feel of the helm for hours on end, and the cold wet ocean spray on their face". In either case, the boat was not designed to have an autopilot installed.

The boat has a Raymarine wheel pilot, but its size, and displacement, exceeds the design specifications of the Raymarine autopilot. It's fine while motoring, or sailing in light winds, but in following seas, or blustery conditions, it does not have the horsepower to keep up. I was called to look at the problem, and see what kind of autopilot options were available. 

In most cases, when a wheel pilot can't do the job, a inside installed hydraulic, or linear drive autopilot will do the trick. These types of autopilots are both stronger, and faster. This boat has a Edson radial drive steering system. In the picture above, as the helm turns, cables pull the flying saucer pulley thingy you see above left, or right, turning the rudder. It's a good system, especially if the rudder is raked back, as is this one.

The large pulley sits on top off the rudder post, and passes through a collar mounted on a fiberglass table. So now we will open the proverbial "Can of Worms". Since this is a cable drive system, the hydraulic autopilot drive system is now a moot point, and we are left with the linear drive approach. All we have to do is to mount a tiller arm on the rudder shaft, and use a linear drive motor to push and pull it. Hmmm, no place up near the pulley thing to attach an arm to the rudder, how about below?

Nope, not below, the rudder shaft is encased in a fiberglass shaft. I call  Edson, and ask if they thought I could maybe attach a post to the outside edge the pulley, and attach he linear drive to it. Edson's reply was absolutely not, and the Edson manual says the same thing. I'm quickly running out of options, when I have a small idea. See the little post with the bolt in it, just under the hole in the deck in the picture below? That is the attachment point for an emergency tiller. The emergency tiller is a pipe section, with a slot in the bottom of it, that fits around the bolt you see in the picture. 

Now, if I did some very careful measurements, I could pull the bolt, and have a tiller arm fabricated, attached to a short pipe section that would fit into the emergency tiller pipe pulley mount. It could be drilled out to allow the original bolt to fit through both pipe sections. Take the original emergency tiller to the machine shop, and weld on a smaller section of pipe that would fit into the now smaller pipe. 

Oh crap, none of this would work, the moment would be lifted, Edson wouldn't approve, it would be a mechanically sloppy fit if it wasn't welded, and if it broke, it would most likely take out all of the steering with it.

As I said there is always a way, but it might not be easy, or cheap, or both. So here are a couple more options, sell the boat, and buy one that you can install an autopilot on, or tear out the existing steering system, and install a hydraulic steering system, or don't be one of those power boat sissies, and enjoy the endless hours at the helm, and the cold wet sea water spray,  Got any idea's?, because I am fresh out of them. Thanks Bill Bishop

The case of the dueling pilots.

It was a gloomy drizzly day. I was sitting at my desk, having a conversation with my old buddy Woodford, when the phone rings. I needed a case badly, and answered the phone. It was a dame with a sultry Danish accent. She was passing through town, and was having problems with a couple of miscreant pilots, and she needed my help. I took a last swig of my buddy Woodford, put a couple fresh AA slugs in my DVM, grabbed my fedora, and headed out into the drizzle. She was hanging out down at the docks, and wasn't hard to find. She was a well seasoned babe, with enough curves to straighten the bent hawse pipe of a freighter. In short, she was my kind of women.

Redundancy is a wonderful thing, but if it isn't done with much care, it can cause endless problems. In this case, it did. This is also a little bit about navigation system evolution.

The boat, a Nordhavn 40 trawler, had originally been originally been outfitted with a Raymarine RL series system, that had a Raymarine RN300 GPS. At some point, one of the two RL80 chart plotters had been removed, and it was replaced with a new Raymarine E-120 chart plotter, with a new radar, leaving the original RL 80 radar as back up. The original RN 300 GPS passed away quietly in its sleep one night, and a new Raystar 125 was connected to the old RL80 system, via Seatalk for position data.

At some point, a second, and redundant autopilot was then added. In the picture above, you can see the new autopilot control head next to the Raymarine E-120. In the picture below, you can see the original autopilot's control head above the console.

This was a first for me. I had briefly seen the boat a year earlier, and provided some assistance to its captain, and I arranged to have some autopilot hydraulic leaks fixed. There are two Raymarine autopilot pumps, two rotary rudder references (one now), two course computers of different vintage, and two autopilot control heads. Below you can see one of the pumps, and the yellow handles are used to change the hydraulic lines from one pump to another. You can also see one of the two original rudder references.

In the picture below is the second hydraulic pump, which is just a couple of feet away from its twin.

The problem with the autopilot systems, was both were tracking poorly. Looking at the boats wake, it was always curvy, and not straight as it is supposed to be. My first sense, was that maybe they were not set up properly, but this was not the case. I also noticed that the rudder bars were flickering, and not solid. Ha, I thought, we have a bad rudder reference here, and I have seen this exact symptom before. So I identify the new autopilot's rudder reference, and disconnect it, but to my dismay, the new pilot's control head rudder bars, are still flickering, and worse, there is no rudder reference connected to it at all, so what's going on? If I turn the helm, the rudder bars still change, but there is not a rudder reference connected, or is there?

I spoke to the clever tech staff at Raymarine, and with some helpful insight from them, and coupled with the slowly dawning epiphany that somehow, both autopilot systems were seeing both rudder references at the same time. It turns out that they actually were.

The original installer's concept, was to install a switch that would remove power from one autopilot, and transfer it to the other. You would then switch the pumps with the valving, and you would be back in business. Even though the autopilot's control head, for the back up system was not lit up, meaning to me, at the time, there was no power, I ohmed out the switch. Lo and behold it was leaking current, and leaking just enough to give the second auto pilot computer some power, but not enough to power up the control head. What was powered on the second autopilot, was some portion of the course computer's system, and the Seatalk network. When I took the second autopilot's power wire off the switch, the flickering immediately stopped. Even though the course computer did not have a rudder reference attached, it still remembered the last position that it had been at, and was reporting it via Seatalk.

What I think happed here, is when the old RN 300 GPS failed, someone used the Seatalk network to provide position data to the old Raymarine RL system with the new Raystar 125 GPS that was connected to the new E-series system, and ended up connecting both Raymarine systems together, including the two autopilots via Seatalk. This could have been better. When the original RN 300 GPS failed, a second GPS could have been added just for it, or the installer could have used a NMEA output from the E120 to give position info to the RL system. Each autopilot should have been tied to one system only, with no link between the systems at all. Redundancy is alway desirable, but it must always be very well thought out.

The boat was leaving, to cross the Gulf to Mobile Al, and they were worried about the oil slick. I was running out of time, so I disconnected the older pilot, did a seatrial, and a new "Auto Learn", and she tracked beautifully. I will think about the problems, and make some suggestions to the owner on how to correct it from afar.

The dame thanked me for handling her scurrilous pilots, but with a sad smile, and a kiss on the cheek, said she had to keep moving on. I watched her curves disappear over the horizon. Oh well, we will always have Sarasota. I pulled my collar up, and fedora down, and headed back through the murk to the office, to visit again with my old buddy Woodford, and wait for another dame to call.

The photo of the Nordhavn 40 trawler is in the public domain, and came from the Picses.eu website