Last Updated: 18 July 2010
(Topica Post 14 Oct 08) For what it's worth,
like Craig, I also filled my rudder with epoxy after finding a crack in 1999
around the post at the top of the rudder. However, there was no movement of
the rudder around the post. I added some high strength silica to the mix and
poured it in the top after grinding a trough around the post, a little at a
time with a slow catalyst. I dropped the rudder in 2005 to have a look and
it was fine then as it is now 9 years and 10K miles later. I do keep a close
eye on it, though.
(Topica Post 16 Oct 08) Great, a lively debate on something important. It's
a good thing that we have all agreed to disagree in this forum. And I
respect opinion regarding building new rather than repairing these rudders.
That is often the best course of action, especially with things like old
stainless (chain plates, tangs and such).
Our Monitor wind vane, is used for longer passages, and can only be used when the dinghy is stowed forward on the cabin top. It is extremely powerful and can handle the boat in almost any conditions except very light or no wind. One of its big advantages is that it uses no electricity. It's disadvantage is it takes some time to set up. See further down this page for more details and pictures of the Monitor.
Most of the time and during times when there is very light or no wind, a wheel mounted CPT autopilot is used. It has steered the boat on a 4 year trip around the Carribbean and up and down the Florida Keys countless times during six years of Boy Scout charters. Its big advantage is that it is very quick to set up and easy to use, but it does use roughly one amp of 12 volt power per hour. We carry three complete units plus multiple spare parts aboard just in case there is a problem. See details below under the section on the CPT Autopilot.
We can also use a small push pull Raymarine 1000+ to drive the Monitor on a compass course when needed. It uses very little 12 volt power and drives the steering through the powerful wind vane. If we want to drive a compass course this is the strongest system we have. It can steer the boat in any conditions from no wind through a gale. We have it aboard but have yet to operate it.
A good link for reading up on self steering, and wind vanes in
particular, is Scanmar Marine at:
The Monitor is a servo-pendulum vane. It is less cumbersome, less vulnerable, easier to install and more powerful than wind vanes which use other principles.
The servo-pendulum system is the most popular principle
for wind vanes in use today. It works well on surprisingly large
yachts since it steers using the boat's own rudder. The more wind
there is, the faster the boat will move through the water, and more
steering power is developed by the servo-pendulum gear. On difficult
points of sail and in harsh weather this is a very welcome
(Jan 2008) Here's some info for anyone interested in purchasing a used Monitor. I've had two of them. The first one was one of the early 80's Larwick models made of all 304 SS. The one I have now is a late 98 Monitor made of all 316 SS. It has all the important upgrades including additional teeth on the gears and the lower tubes support bar which all were added in the mid to late 90s. Larwick sold the company to Scanmar Marine in Ca in the early 80s. Scanmar is the same company that bought the CPT Autopilot company in the late 90s. To determine which unit you may be looking at, look for the date on the forward horizontal support tube beside the Monitor sticker and the word Monitor. Mine reads "Monitor 5906 1198. The 5906 is the serial number, 1198 is Nov 98. They changed to all 316 SS sometime in late 97.
I paid $1800 for mine in 2005 with spares and a wheel mount. The wheel mount is $400 new and the entire unit runs close to $4000 new now. The price of SS has gone way up. A friend bought a 2001 at about the same time for $2000. I've seen them on SSCA for $1500-2000 in the past couple of years.
There is lots of detail on the Monitors at Scanmar's website, including the parts breakdown I believe. Google Scanmar Marine or Monitor Windvane. If the unit you are looking at is in mint condition and a 98 or newer I would say it is now worth $2000 or a bit more. But if it is earlier, I would offer more like $1500-1700 depending on the date and which upgrades it has. If it is a 97 call or email Scanmar with the serial number to find out which SS it was made with.
(Topica Post 14 Jan 08) Like most things with a boat an autopilot is a
compromise. Your choice will depend on what you want the AP to do, and how
much money you can spend on it. If it is intended to drive during reasonable
wind/sea conditions and you have a wind vane for heavy conditions then a
lesser AP, preferably one that you can repair yourself, will do fine. Heavy
blue water conditions require a first class AP like the W-H or a strong wind
vane or both. The trade offs here are that a strong AP will require lots of
amp hours to run and the wind vane will not. However, the vane requires wind
and the AP does not. There is a work around for the vane in no wind
conditions using a small tiller pilot to drive the vane.
After the Summer charter season was over I spent time checking all the external wiring and connections in the hope of finding some simple solution. There was none. I checked the internet for any mention of CPT and problems with it. There is a good bit written about problems owners are having with the unit and with Scanmar but no actual repair information. So I opened both the drive and compass unit boxes and carefully inspected the circuit boards and wiring connections for obvious problems with a head mounted magnifying glasses. I found none. Finally I enlisted the help of a friend, Wes Whitley, who had extensive electronics trouble shooting experience. Here's what we found and what we did about it:
1 I now have parts from 4 different units-two pre 1990 (Autopilot-one serial number 3309 the other not available) and two about 1997 (Autopilot II-serial numbers 14150 and 14267). One I bought new in 1997, the others have either been given to me by frustrated owners or I have bought for less than $100 after mine started acting up. I have recently acquired a working fifth unit (Autopilot II-serial number 14378, newer than all the others) for $40 here on the Rio Dulce. It was just too good a deal to pass up and gives me two version II working spares for our circumnavigation.
2 A close examination of the two circuit boards in each unit and the compass itself reveals that there were only minor component changes, mainly manufacturer, over those years. All the components on the circuit boards are off the shelf parts readily available through parts houses such as Digi-Key (digikey.com, 800-344-4539) for very little money. The boards are large enough that anyone with a fine soldering iron, a solder sucker, good eyes and a little soldering skill would have no trouble replacing bad components. I consider this a real plus for someone going offshore or to third world countries with an autopilot or any other piece of electronic equipment. The main problem with trouble shooting this unit is that there is no circuit diagram available. Even so we were able to fix our problems with just basic trouble shooting techniques. So that I can get going in a hurry again if a unit should stop working, I now have both the drive and compass units wired with short leads to easily accessible terminal boards. They can be quickly replaced with the spares while underway with a minimum of work.
3 The drive unit was sold with two different motors but the same circuit board and case. Sometime in the 1990s CPT began using a 24 volt Bosch motor instead of the older 12 volt motor. The newer unit with the 24 volt motor has a II behind the Autopilot name. All the circuit boards in the drive units were identical in the way they fed 12 volts to the motors. According to Bosch feeding 12 volts to a 24 volt motor allows it to develop more torque and therefore become a more powerful unit. If you want a spare, the 24 volt motors, PN 0390257693, with gearing attached are still available for about $100 each. Call Mike Juliano at Bosch in Texas at 972-625-1075/1. He would love to get rid of the 40 or so he has on the shelf, made specially for Scanmar. So far, I have been unable to find anyone with a circuit diagram, and Scanmar, the current owner of CPT is unwilling to provide a copy or even discuss trouble shooting as mentioned in previous posts on Sailnet.com and other lists. BTW the rights to CPT are for sale from Scanmar if anyone is interested in becoming the world distributor/repair facility for CPT. There are 14,000 plus units out there and from what I've read from frustrated owners it might be a good business.
4 In order to bench test the various components of each unit we cut the 4 wire cable between the drive and compass units on each, set them on a work bench and provided 12 volts to each drive unit while alternately connecting up different combinations of compass and drive units. By rotating the compass dial clockwise and counter clockwise we could easily see which units had problems and which did not.
5 In order to get the units open I had to first remove the black plastic trim around the rim of the boxes, then carefully use a sharp long thin knife (like a long blade box cutter) to cut the silicone caulk between the outer case and the aluminum face plate. It is necessary to cut the caulk about a half inch in from the front of the face plate. The corners are the most difficult but with perseverance and a narrow blade, after all is cut the faceplate can be gently pulled out by the knobs and rocking the faceplate back and forth.
6 My original unit, new in 1997, serial number 14267, had several problems. The main problem was that the drive unit circuit board relays had finally worn their points, after about 10 K miles, so that they were too badly pitted to supply current to the motor. They are small black plastic sealed boxes about an inch square with five soldered connections on the bottom each. After removing and replacing both I cut the top off both boxes. The relay that drove the unit to starboard had very badly pitted points and could no longer carry current. The other was not quite as bad but in marginal condition. Their cost was $1.42 each through Digi-Key. It took about a half hour to replace them. The other problem was a loose capacitor found by touching each component on the circuit board in turn with the unit on and in the null position. When we moved this particular capacitor the unit activated intermittently. Inspecting the solder connections with a strong magnifying lens revealed a loose, solder starved connection. This was a two minute fix. We also checked the diodes and 4 IC chips for loose connections and found none. As a precaution against future problems we went ahead and replaced the 4 IC chips. I purchased all the replacement components and several of each for spares as listed in 8 below from Digi-Key.
7 Since we were already inside the boxes, we also took the time to heat and cool each component separately, a common trouble shooting technique, to see if there were any problems temperature extremes would cause. There were none. As mentioned above, replacing any of these components is easy, if you have the component, proper tools and a little soldering skill. Taking the various components apart including the compass unit and its numerous gears and contacts is also not hard, but does requires keeping track of how they will go back together. The hardest part is getting the boxes open and resealed properly.
8 One of my older units when given to me was "not working, couldn't hold a course and was a piece of trash" according to the previous owner. It turned out to only have a bad compass; the 12 volt motor and two circuit boards were in perfect working order. After taking apart the compass itself I found that the oil inside had become somewhat more viscous so that the needle was very slow to follow a course change and sometimes even hung up completely. I could probably be easily fixed by replacing the oil with mineral/compass oil. This may be a class problem with pre 1990s units as the oil ages or the unit bakes in the hot sun. I keep both my units covered with Sunbrella and under the dodger extension. The compass unit circuit board was working well when we tested it with another compass. I have not been able to find the source for the compass itself as there are no markings on it. That would be an interesting project for someone with good internet search skills or who knows the original owner of the company, Charles Pukit.
parts I ordered through Digi-Key were as follows:
All my CPT Autopilot II units use the Bosch
24 volt motor. CPT shifted to the 24 volt motor in the 1990s. Older, pre
early 1990s units used a 12 volt motor. All the units feed the motors 12
volts and need 12 volts coming in. Mike at Bosch in Texas, where I bought a
spare motor several years ago, told me that a 24 volt motor works better
(more torque?) than a 12 volt motor being fed 12 volts and that is why CPT
made the change in motors. Maybe some electrical engineer among us can
Below find pics of the components for a future project involving using parts from a Raymarine 5000 autopilot to substitute for the CPT brain and compass in order to allow the strong CPT motor to drive the boat through the smarter Raymarine control head unit and compass. According to Paul on Peter Rabbit this works well and allows him to drive a route generated by his GPS and computer navigation system without having to continually adjust the autopilot. This would be very useful on a long passage with little wind. The Raymarine fluxgate compass and rudder angle indicator are also used with this system. Since this particular unit is no longer made by Raymarine it is available on Ebay for less than $500. There are also several pictures of the components Paul installed on his boat.
In order to take the weight off the delrin pad in the
underwater heel plate and allow the rudder to turn more freely this pillow
bearing was installed at the top of the rudder post under the aft berth.
By lifting the rudder assembly about a quarter inch and then installing the
pillow bearing on a strong bulkhead, the rudder now hangs on the bearing
instead of riding on the heel plate.
This gives a much smoother and stronger mount for the rudder.