Catalina 27 Chartplotter Swing Arm Install

[SVCeviche]

Hey everyone - I wanted to share an installation we recently did on our 1985 Catalina 27. I haven't seen anything that walks through the full process online, so I thought I'd share our approach.

Open to any questions, but the process was pretty straightforward.

1.) Built mounting block to compensate for the bulkhead angle
2.) Marked mounting location with painters tape
3.) Drilled two pilot holes into bulkhead, with matching holes into mounting block
4.) Applied 4200 to the mounting surface and block, and attached the block with screws
5.) (Ideally here you let it fully cure - we couldn't wait)
6.) Attach vertical mounting plate for RAM mount

For the mounting block, we glued 4 pieces of an oak hardwood plank together. We cut one side (the side that attaches to the bulkhead) at the same angle of the bulkhead so the arm would sit straight. We sanded and stained it to match some of the other interior trim, and then sprayed on some polyurethane.

The mounting method was the hard part given different requirements for different materials and uses, not to mention the considerations for a boat (high moisture, high-shock movement, etc.). Ideally, you'd use machine screws to go through the bulkhead and into a washer or flat backing plate or bracket. We really wanted to try and keep the outside clean, which disqualified that option. We also felt that screws that were only partially inserted would be too shallow and might not hold given the age of the boat ('85). We didn't want to rely too heavily on the bulkhead given its unknown structural integrity. This is the other reason a mounting block worked well - it gave lots of surface area for the 4200 to grab onto.

 

[Stu Jackson]

That is superior work, thx for sharing. Many boats have that same profile. Heck, my C22 & C25 do, too. Well done, and thx for the flix.

 

[Joe]

Nice work! Hope you don't mind if I comment on your mount location. I have similar setup, although on starboard side because of dinette configuration. I mounted the block closer to the hatch's edge so the second elbow reaches directly into the cockpit area. The location allows easy viewing angle adjustment and convenient operation of the device itself without moving away from the tiller. A bonus is the passageway is less obstructed. Again, nice job.

 

[HukilauMike]

Very robust arm and mounting job. Thanks for sharing! On my last boat (O'day 23), I went in the opposite direction with the mounting of my chartplotter. I went cheap and easy.

After taking some general measurements on the boat (how far out I needed the unit to swing, available area for storage, etc.), I went to Amazon and bought an inexpensive swing arm made for a small TV. I think the unit cost about $19, including tax and delivery. I made a mounting board for the plotter out of some spare starboard I had lying around so I could affix the plotter to the arm.

To mount the arm to the bulkhead, I had to do a little prep work. The bulkhead liner was way too thin to securely mount the arm and support its movements, so I had to bulk it up a bit. Fortunately, the PO had already made a nice big hole in the bulkhead to mount a knotmeter. I had removed that knotmeter years before as it was non-functional, so I just had a big hole on the inner and outer bulkheads (you can see how I covered the outer hole with some teak in one of the photos. To support the mounting of the arm, I used the inside hole to reach into the space between the inner and outer bulkheads and gorilla glue a 1 inch furring strip of wood to the inside of the inside bulkhead. I was then able to use some robust wood screws to directly mount the arm to the bulkhead through that strip. I was also able to use that same space between the bulkheads to run the wiring down to the transducer in the bilge.

I was kinda proud of that set up. I got some "that cheap steel will rust out in a month" and "that arm won't stay put in rough weather" kind of comments, but I never had a problem in the five years I used it before I sold the boat.

 

[tfox2069]

Did the exact same mounting on our 1974 Catalina 27 (sold it 2 years ago) for a Navman black and white chartplotter we got on the clearance table at a West Marine in 2006. Fantastic solution for those boats. Thanks for documenting it for others!!

 

[PSR]

Nice work.... Why did you need to make the mount vertical with the angled oak base?

 

[PSR]

Here's my installation, which has no mounting block, with screws into the bulkhead-extremely solid:

....and my favorite recent photo (6.6 kn SOG-reaching in ~15 kn wind, flat water, in the Richmond Channel)

Peter