We loved the hydraulic units because a hydraulic ram is nearly indestructible. The only thing that can really go wrong is a bad seal and that can be fixed anywhere in the world. A bad pump can be swapped out fairly easily in a remote spot. When the rudder was not supposed to be moving the hydraulics lock it in place with much less strain on the device than the mechanical drives. The linear drives are more fiddly, with gears and bearings. They would tend to get chewed up under heavy use and are not easily fixable in Samoa or Bermuda – they pretty much have to go back home for repairs. Remember this is me spending other people’s money ;) Now if you already have a linear drive it isn’t like it won’t work – they will steer the boat. In your install make SURE there is no lost motion with the mount flexing. That will feed back through the rudder sensor and the thing will endlessly be going back and forth. We had boats where the HULL flexed enough to cause this issue and we had to get reinforcements glassed in.
Joe Della Barba – owner of a really cheap old autopilot From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of Dave Godwin Sent: Tuesday, March 26, 2013 10:19 AM To: cnc-list@cnc-list.com Subject: Re: Stus-List Autopilots Joe, In light of your last post I have some questions. Mainly because I seem to have set about adding an under-deck autopilot doing exactly the opposite of your recommendations. I’m not trying to be contrary and am very interested in your take on the matter. After yeoman’s service on my 37’ (~15,500 lbs) the old Raymarine ST4000 succumbed and went on to the choir invisible. That after being rebuilt once and I too got the “please don’t call us again" message. And frankly, I was done with wheel pilots. I didn’t care for the noise or the “clutch on/clutch off” aspects of the type. I purchased a Raymarine Type 1 Linear Autopilot and (then new) ST5000 course computer with auto-gyro. I went with the linear drive for two reasons: cost and perceived value. The value part being that I’ve used several of the tillerpilots, one on a Cal 40 and have been very impressed with their power, simplicity and ruggedness. So, my questions to you are 1.) did I goof with the linear drive as regards my boat and by doing my installation will I regret it? Also, what is it about linear drives that are problematic from your perspective? (Bonus question!) I should describe my installation (and I can provide pictures via email…). Because the ONLY access to the stern and port quarter is to contort myself and slither aft from the starboard cockpit locker and this would be compromised by permanently placing the drive there (base of the drive unit outboard with the arm extending inwards to the quadrant I decided to make the mounting base for the drive removable. I tabbed two short sections of ½ fiberglass sheet material (McMaster-Carr) to the hull, fabricated a U-shaped platform, again using ½” sheet stock with 90 degree angle ¼” stock to reinforce the inside of the platform structure. This I then fit down inside the two tabs and bolted the whole assemblytogether with four ¼” SS bolts, fender washers and Nylock nuts. The linear drive was bolted to the top of the platform. This way, if the need arises to get aft I can unbolt the whole mess… So, workable? Mistake? Cheers, Dave 1982 – C&C 37 “Ronin” Sent from my iPhone On Mar 26, 2013, at 9:11 AM, "Della Barba, Joe" <joe.della.ba...@ssa.gov<mailto:joe.della.ba...@ssa.gov>> wrote: I have an AH 400 unit from about 1988, so it has been working for 25 years now. Kind of like George Washington’s ax, the drive and the computer have all been repaired more than once. This is no thanks to Autohelm/Raytheon/RayMarine, who told me to NEVER send it in again for repairs again after fixing it around 1994 or so. These are light duty autopilots that cannot handle heavy air going downwind. Going to windward they do pretty well. I used to be in the business of selling and installing autopilots in the mid-90s and what we learned then was you want the BIGGEST drive you can fit and afford, not the smallest drive you think might work. We used Octopus brand (division of Teleflex) hydraulic drives for all our installs. They worked fine with Raytheon and other autopilot brands. We never did like the electric linear drives and tried to stay away from them. You really need to know what you are doing or hire a pro to install the drive. The forces it can produce are enough to do real damage to a boat if you set it up wrong. BTW, for long distance sailing I read about adapting a tiller pilot to the bottom half of a windvane steering system. This used almost no power and the tiller pilots are cheap enough to carry spares. Joe Della Barba Coquina C&C 35 MK I _______________________________________________ This List is provided by the C&C Photo Album http://www.cncphotoalbum.com CnC-List@cnc-list.com<mailto:CnC-List@cnc-list.com>
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