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
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