[C320-list] Another Autopilot followup

[Jeff Hare]

I'd like to second Chris's comment on a home-brew version of backing plates to save cash on this project.  The larger longer backing plate for inside the cockpit locker that the RAM will mount on should probably be just an inexpensive piece of 3/16" aluminum plate. The RAM's base plate is aluminum so that keeps similar metals together. The plate in the aft cabin should be made to look nice, so polished or brushed stainless would look better there. Brushed stainless will not stay quite as classy looking as polished over time.

It's important to remember that that aft cabin wall is very thin material. It's important to sandwich as much of that wall between the two plates as you can to prevent the RAM from damaging the wall. It's also a good idea to use a little Sika 291 or 3M 4200 on the plates to help make the bond rigid.  Probably not critical if you use a long Aluminum plate inside the locker, but it's a good idea.

You can easily cut/shape stainless with one of the inexpensive portable bandsaws from harbor freight or even the cordless ones from Milwaukee or similar. Then to clean up the edges, an angle grinder with $4 120 grit flap-disk will shape it down from your rough cut to the finished pattern line and polish the edges in minutes. Way better than trying to use a grinder stone.  Just keep a rag and a dish of ice water to dab on it every few seconds. Then you won't have any bluing of the steel. I just did a similar thing recently and was done in a flash with a professional looking piece.

If you have a piece of stainless that isn't mirror polished, you can get some of these angle grinder flap disks that are 320 or finer grit and then use a few grades of inexpensive angle grinder polishing disks with to give it a professional finish.

We have a CAD file with the profile on it and also 1:1 scale PDF that you could print out and use as a pattern for marking the backing plate.

If I didn't know a guy with a machine shop that was happy to make one for me, I would have gone this route probably.

Also, I have yet to see a C320 rudder post that isn't the same diameter as all the rest, so mostly you're just confirming that yours isn't some odd size. The slight variations I've seen are all within the error margin of different people using different scales to measure the post. It's worth checking on early hull numbers and also on the MKII boats of course, but Catalina is pretty consistent on their specs and made a lot of them. Deviation could cause unexpected problems on the assembly line.

-Jeff

-----Original Message-----
From: C320-list <c320-list-bounces at lists.catalina320.com> On Behalf Of Chris Burti
Sent: Monday, February 21, 2022 5:09 PM
To: 320 <C320-List at catalina320.com>
Subject: Re: [C320-list] Another Autopilot followup

The 'custom' mounting plate is a pretty easy DIY project with a piece of scrap 5" x 6" x 3/16" stainless scrap. Mine didn't cost me anything.

More pricey is the Edson bronze rudder arm you need to connect the drive to the rudder post. The rudder post has to be measured precisely and the arm is custom bored by Edson...then you have to cut about an inch or so off the end because it is too long.

Totally worth it!

Chris Burti
Farmville, NC



On Mon, Feb 21, 2022 at 3:59 PM Scott Westwood <scottwestwood at bellsouth.net>
wrote:

> In order to go from wheel to linear Autopilot I would have to:  at a 
> minimum add the linear drive (about $1800+/-?) and also replace the 
> ACU (about $800).
> Yikes.  That is not including the custom mounting plate that needs to 
> be made.
> Missing anything?
>
>
>
>
> Thanks,
>
>
>
>
> Scott Westwood scottwestwood at bellsouth.net C (919)- 819-9794
>