Joe, thanks. Good points about the flexing issues. I know that the mounts for the setup that I constructed are rock solid but now I’m rethinking the placement issue vis-à-vis the hull. I can imagine the hull flexing in that location. The nearest bulkhead is a good 18” or better away. I have no current plans to go to Bermuda nor do major offshore work. Bahamas at most. 90% on the Bay I suspect, with the occasional trip to New England. I think that I’ll spend time monitoring the system, particularly in heavy seas whenever I find myself in those conditions. If it proves to be a problem then I’ll go back and reinforce the hull in that area. Best, Dave 1982 C&C 37 – “Ronin”
Sent from my iPhone On Mar 26, 2013, at 11:07 AM, "Della Barba, Joe" <joe.della.ba...@ssa.gov> wrote: > 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> > 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 > _______________________________________________ > This List is provided by the C&C Photo Album > http://www.cncphotoalbum.com > CnC-List@cnc-list.com
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