Ray Marine Component System

I spent several years trying to make this system work reliably and eventually removed it completely and transitioned to an Autohelm ST4000 Wheel system. This system worked well for coastal passages, especially as a backup for the self steering vane. However, the during the Norfolk to the Abacos passage of 9 days it became apparent that it was not up to long distance passages. It is possible to help it along by pouring a cup of hot water into the gear mechanism twice a day to clear the salt crystals.

The third autopilot installed on Botany Bay was an ST1000+ linear drive autopilot connected to the Monitor self steering vane. I used this system successfully between Redondo Beach and Catalina Island under moderate conditions. However, significant changes in standing helm can overwhelm the ability of the self steering vane to correct and have unpredictable results. This system continues to provide a backup for the below decks autopilot currently installed and in fact steered Botany Bay under nasty conditions coming up the backside of the Hawaiian Islands going into Honolulu for repairs.

The current primary autopilot on Botany Bay is a Ray Marine component system autopilot comprised of the following components:
     Type 300 Course Computer
     Type 2Long Linear Drive
     ST7000+ Control Head
     ST600R Remote
     Gyro+ Yaw Rate Damper
I can't say enough good things about this system, it steers in the worst of conditions, it never is underpowered, and the Gyro+ yaw Rate Accelerometer makes an amazing difference in difficult following sea conditions. For the passage back from Kwajalein to Los Angeles I upgraded Botany Bay's wind indicator to a Ray Marine ST60 series instrument. The result of adding a masthead windpoint on the SeaTalk bus is that the autopilot has access to high speed updates (faster updates than provided over a NEMA link) and maintains very accurate apparent wind angles when commanded to do so.

A word is in order about the choices between self steering vanes and autopilots (especially large, below deck mounted, fast autopilots). The Ray Marine component system with Gyro+ Yaw Damping (or the new Type 150G or 400G Course Computers with built in Gyro+) appear to do as good a job of steering as the Monitor Wind Vane (which is saying a lot, the Monitor wind vane can handle just about anything I can throw at it!) and the autopilot has the benefit of responding well to radical changes in weather helm (for example during a sail change or setting a spinnaker). However, there are two significant reasons to consider the self steering vane AND the below decks autopilot.

The first is power consumption. I deliberately choose to run the autopilot exclusively for the downwind run from Hawaii to Kwajalein to examine this issue and test the replacement drive motor installed in Hawaii. I found that under moderate conditions the system consumed approximately 70Amp Hours/Day. This was measured using the secondary shunt on the Link 2000R energy monitor system. During rough conditions with the autopilot running at response level 3 (only level which uses the Gyro+ for this model) the consumption can easily be twice that.

The second is redundancy. While I now have about 7000 open ocean miles on the installed Type 2 Long linear drive I did experience a failure of the first drive unit installed on Botany Bay. I was only using the autopilot at that time during sail changes and it failed with less than 10 hours of use. The technician in Hawaii and I examined the unit and found that the brushes had failed to seat correctly on the commutator and had put carbon dust everywhere. I had determined at sea that there was a position where the drive motor had infinite resistance and thus deduced that either the commutator was fouled or that a motor winding had failed as an open circuit. The fouled commutator was the cause and if it had not been for warrantee issues I could have easily cleaned it up with a point file and some care. If a drive motor had not been available in Hawaii I would have continued onward to Kwajalein and attempted the repair at sea and I feel it would have been successful. I now carry a spare drive motor (~$100US) and a spare gear cluster (~$75US) for the Type 2 Long drive unit there is an additional drive belt which is a Gates PowerGrip GT part number 3MR300-12-7-358DS which connects the drive motor to the gear cluster. For the passage back from Kwajalein to Los Angeles I also carried a spare drive unit borrowed from a friend at Kwajalein (Thanks to Paul Mosely!) and mailed back to him.

Thus, the choices I see are as follows: Redundancy is a must, either 1) a large below decks autopilot AND a self steering vane or 2) a pair of identical autopilots (or very similar, i.e. interchangeable components for some or all of the systems) and the ability to switch out components easily. 

For Botany Bay the current fallback plan looks like this (assuming you need the autopilot and not the vane):
1) Ray Marine Below Decks Autopilot
2) Backup control head (ST600R) in case the ST7000+ head fails
3) Backup drive motor for linear drive
4) Backup gear drive for linear drive
5) ST1000+ autopilot driving Monitor Self Steering Vane
6) Hand Steering

Note that when the main autopilot fails the quick fail over is the ST1000+ driving the Monitor Self Steering Vane until the main autopilot is back online.

If I were to choose the to similar autopilot route I would have a system comprised of
1) Two identical Type 2 Long drive motors on opposite sides of the quadrant, always hooked up
2) Two Core Packs, 
         The current Type 300 Core computer with Gyro+
         An Updated Type 400G Core Computer with Integral Gyro+
3) The current two control heads (Both are capable of full control)
        The ST7000+ Primary Control Head
        The ST600R Remote Control Head
I would wire the system such that only one drive motor can be engaged at a time with a set of switches to hook either Core pack to either linear drive. This would also require two independent SeaTalk buses aboard to avoid conflicts between the two core packs. 

The idea would be that I could swap to either the primary or secondary core pack/linear drive chain buy connecting the SeaTalk bus to the appropriate core pack and engaging the pilot. If the failure was then diagnosed as a linear drive failure then the connection between the core packs and the linear drives could be swapped with a switch and the primary (preferred) core pack used with the backup linear drive. In a similar way there would be redundant rudder angle transducers and flux gate compasses which could be swapped between the two systems at the flip of a switch. These redundant systems provide the ability to quickly diagnose the failed component, have the system functional quickly, and know which replacement parts are required to bring the system back to full redundancy. Additionally this type of online redundancy reduces the need to carry spares which are never tested. 

Now, back to the issue of which is best? This depends if  your vessel can handle the 70Amp Hours/Day (or twice that for a hydraulic unit) all the time and you don't mind the minor noise of the electronic drive unit then it is moving. This means that the electrical system redundancy is at least as important as the autopilot system redundancy. The self steering vane will continue to work with no power when following the wind and with less than 0.5 amps of current on average when using the small ST1000+ linear drive to command it.

Botany Bay Quadrant and Linear Drive

Here is a photo showing the installation of the Raymarine Type 2Long Linear Drive as well as the rudder angle reference transducer. Of specific interest is that the mounting point for the linear drive where it attaches to the hull is in the same plane as the quadrant. This ensures that the linear drive force is always perpendicular to the rudder shaft ensuring no loss of force or binding.

The connection of the autopilot to the vessel must be very strong. The type 2Long linear drive can easily generate some 1200lbs of force and the load can be cyclic which tends to break things. To install the linear drive I glassed a thick piece of plywood to the hull and a bulkhead to make a very firm mount. I have seen no indication that it is moving.

This is the remote for the autopilot. The ability to carry it around and adjust the autopilot from anywhere on the boat is really useful.