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Wednesday, December 21, 2011

Installing a Panelized Overhead in Your Cabin


Capt'n Pauley's Virtual boat yard has this very interesting project panalizing the overhead in the cabin. Here's how he did it...........
The headliners in many older boats are on their last legs, dirty, off-white and sagging in places and are a prime candidate for replacement. I decided to replace mine with one with removable access panels. A prime advantage is that it allowed me access to the fasteners holding on the deck-mounted equipment.
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Concept
The idea behind a panelized overhead is to divide the overhead area into manageable panels. These panels are then individually and easily removed to access any fittings or fasteners located on the overhead or to add new hardware to the deck above.

My method would be to bond a series of flat plywood panels to the overhead. Teak trim strips would define the shape of the removable panels that would be held in place with Velcro.

I used 1/2” MDO plywood for the fixed panels. MDO plywood is “Medium Density Overlay” plywood and has a phenolic paper layer bonded to one or both sides. Exterior glue is used and the core has no noticeable voids. Better than marine plywood in many respects and far cheaper. The phenolic paper surface is also extremely smooth and ready for paint or epoxy.

Prep work

My first step in the process was to remove the existing headliner. While I was working on the overhead, I also replaced the side cabin paneling with new ash plywood, installed an additional storage locker over the galley sink and added additional posts, from the side of the galley and the nav station to the overhead.

Design

The first step was to make a scale drawing of the area to be panelized, including all existing hardware, openings or other items that would affect the layout. I experimented with different layouts until I had one that looked good, allowed access to all the pertinent features and avoided all the encumbrances on the overhead.

The next step was to transfer the design to the overhead of the cabin. I established a centerline, using the center of the companionway opening and the mast surround, with a string. Working from this centerline, I cut out the individual sections from sheets of 3/16” artist’s foam board, held in place with tape or spring loaded shower rods and with the locations of all the teak trim strips.

Fabrication
I rough cut the panels to shape using my saber saw. Trimming to the finished edge line was easy. I have a workbench with a piece of aluminum screwed to the edge. I line the cut line up with the aluminum and clamp the plywood in place with a couple of quick release clamps. A router bit with a ball bearing on the end rides on the aluminum edge, trimming the panel to shape quickly and accurately.

I marked the location of the teak trim strips on the face of the panels and cut the center of the panels out, leaving a 2” rim or frame around the edge to allow access to the overhead equipment and fasteners. The cutouts also lightened the panels considerably.

I used a round-over bit in my router to ease the inside edges of the panel openings.  To save some time and overhead work, I painted the panels at this time. I left the rear or upper side of the panels uncoated for the epoxy that would hold the panels in place.

NOTE: I usually give plywood a coat or two of epoxy for protection. I only did one panel this way and found that I couldn’t drive the staples for the Velcro into it!

Panel Installation
The entire overhead was washed down and then wiped with acetone. The areas where the panels were to be bonded in place were lightly sanded with 80-grit sandpaper.

The center panels were installed first and lined up with the centerline established earlier. The cabin top on my boat is cored, which allowed me to fasten the panels in place with stainless steel self-tapping screws.

Once the panels were all in place and adjusted to give a smooth, level surface, I removed them one at a time. As a panel was removed, I gave the back or upper side a coat of epoxy, which soaked into the bare plywood. I then applied a generous amount of epoxy/filler, mixed to peanut-butter consistency, to the epoxy coated plywood and the panel was screwed back in place.

Once all the panels were bonded and screwed in place, I gave the entire overhead a light sanding with 80-grit sandpaper, then primed and painted any bare areas.

Trim Installation
Most of the teak strips were standard 1-3/16” teak battens. I decided to install 1” x 3” mahogany trim strips above the inside handrails. This spaced them out so they were integrated into the overall panel design. Longer fasteners would be used to re-bolt the handrails in place. Since these handrail trim strips were to be bolted in place and were substantial pieces of lumber, I added eyebolt anchors for future lee cloths. The mahogany was stained with Minwax Special Walnut to match the existing teak d├ęcor.

Starting from the center, the teak trim was cut to size and screwed in place using #6-3/4” flathead self-tapping screws. You could countersink sink and bung them if you like but I have an aversion to bungs. Once the strips were all in place, I removed them and gave them all six coats of Interlux #60 Rubbed-Effect varnish before reinstalling them.

Removable Panels
I again made patterns for the removable panels from artist’s foam board, recycling the foam patterns from the MDO panels. The patterns were cut to allow a 1/16” gap around all the edges to allow for the thickness of the vinyl material. I cut the panels from 1/4” exterior luan plywood, with the edges sanded to a slightly rounded shape and marked which side faced the vinyl covering.

I covered the panels with a white marine upholstery vinyl I bought at a surplus fabric store. The fabric was placed on a table with the good side down. The panel was placed on top of the vinyl, making sure the proper side is down against the vinyl and cut the vinyl around the panel allowing about 2” around each side. I used an Exacto knife with a #11 blade for all my vinyl cutting and trimming.

Starting from the center of one side, I folded the fabric over and stapled it in place, using 1/4” Monel staples. I then moved to the opposite side and stapled that center in place. Working from the center out, I stapled the vinyl in place, stretching it as tight as I could.

The corners were then trimmed and stapled in place. It would be a good idea to make a couple of small sample panels and practice your stapling and trimming on them before the real thing. Develop your skill with the corners as these take the most time.

Final Assembly
All the removable panels are held in place with adhesive-backed 3/4” wide Velcro.
Velcro has a hook side and a loop side. I decided that all the hook tape would go on MDO panels and the loops on the removable panels. This was just to make sure I kept everything sorted out right. The adhesive couldn’t be depended upon to hold the Velcro in place indefinitely, so I also stapled the Velcro in place with an electric stapler.

With the Velcro firmly attached, I could then press the panels in place. It’s amazing how tightly the Velcro holds the panels in place. I not only haven’t had any panels come loose, I actually have to pry them off. I found the tool that paint stores sell to open paint cans ideal for this job.

Recap
I know this all sounds like a LOT of work, but it actually went surprisingly fast. Would I do it again? You bet!  I love the way it looks and the easy access it provides to the underside of the cabin overhead. It’s a winner as far as I’m concernened.
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 Making foam board patterns for MDO plywood panels
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MDO panels cut out, painted and ready to install
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Aligning panels with self-tapping screws
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MDO panels epoxied and screwed in place.
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Installing teak trim strips
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Stapling Velcro on vinyl covered removable panels
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Velcro stapled on MDO panel
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Finished panelized overhead

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