Autopilot linear drive mounting in C-36 Mk. I

[jviss]

Greetings,

For those who have installed an autopilot linear drive in a first-generation Catalina 36 (mine's a 1984 model), how did you do it? Was there a good place for mounting the fixed part (base, foot) that left the ram at the right height and angle? If you had to fabricate something, what was it? Any pics, links, etc., appreciated.

I'm going to do this, and I want to get to the boat prepared with all the materials and tools I might need.

Thanks,

jv

 

[Stu Jackson]

Try the C36 Association website

they have a great writeup by Larry Brandt.

 

[jviss]

they have a great writeup by Larry Brandt.

Hi Stu,

Thanks, I have already read that article. Well written and illustrated!

One issue I have, and I have seen this on more than just Larry's installation, is the mis-use of the design features of the tiller arm. The arm is designed so that the ball-end would be inserted into the slot in the arm, and a clevis pin inserted through the arm sides and ball end, secured with a hair-clip clevis. Note that Larry has followed Raymarine's instructions to the letter by installing their pin; I believe Raymarine assumes a tiller arm without a slot. Here's a pic of Larry's installation:

The obvious design advantage of the Edson tiller arm design is that there is no twisting load on the arm if the ball end is installed in the slot. The twisting load can add "slop" to the setup. Here's a pic of one properly installed:

Well, almost properly installed. In this case this user is using the slot, but it does not appear that the pin can be pulled out easily, in an emergency, as you should be able to do, in the event of a linear drive jam.

If I use the Edson arm I will pilot-drill the holes through the arm, on a drill press, and then ream them to a close fit with the pin. Pins can be 0.500", or they can be 12mm, depending on the ball end.

That radial drive wheel looks plenty sturdy to me, though, and I think I'll just make a bracket that attaches to it for a pin to drop the ball end onto.

jv

 

[Stu Jackson]

jv, why not

discuss this directly with Larry, he's active on the C36 MB. Or ask him to join us over here, too.