Between 2007 when we acquired our Roamer 46 and 2012 when the refit resumed after a long hiatus while I cleared up the US Coast Guard paperwork SNAFU, I had lots of time to think about how best to rebuild the salon roof hatch. I also had the benefit of seeing how the salon roof hatch was designed on a 1968 Chris Craft Commander 42 we bought in 2011, which led me to conclude that the original design on the Roamer was reasonably sound. The hatch failed on the Roamer because 1) somebody cut notches in the longitudinal hatch frames, which caused the frames to crack and 2) they only used 3″ fiberglass tape to cover the cut in the FRP cabin top skin when the boat was repowered with 534ci Super Seamaster twin turbo engines in 1973.
When rebuilding the hatch in 2013, I made sure it would never fail again.
Because the salon roof structure was compromised for so long with the hatch and frames out, the roof had settled. The FRP skin was extremely wavy in certain areas from the lack of support. Using 2x3s and a floor jack under each of the remaining frames, I got the roof back up into the original position.
This shot shows where we cut out the rotten 1/4″ plywood underlayment for the salon roof, then roughed up the underside of the FRP skin with 36 grit on a grinder (around the left-most frame).
The rotten plywood was cut out and the under-side of the FRP was ground and ready for bonding in the new 1/4″ marine plywood. We were starting to fit the 1/4″ plywood here.
Once all of the pieces were in place, we drilled and countersunk holes from the topside for #8 x 3/4″ screws that would mechanically fasten the two layers together.
The original roof frames, one of which is on the right above, are 1-3/8″ wide. I had 300 board feet of 8/4 (i.e. 2″ thick) African mahogany and decided that we would keep the new longitudinal frames as thick as possible. Once we had the boards jointed and planed square, they were 1-7/8″ thick…lotsa meat and NO NOTCHES! 😉
The process was to wet out the plywood and underside of the FRP skin with US Composites 635 epoxy. Then, using the same 635 epoxy, we used fumed silica filler to make a bonding agent and spread that in a nice layer across both surfaces. After fitting the plywood and screwing it to the FRP, we put clamps everywhere to help hold it all together.
While grinding back the ancient gelcoat in preparation for covering the salon hatch hole with fiberglass, we found evidence of a previous repair. There was also evidence that the original FRP layup wasn’t wetted out as well as it should have been. But more on that later…
I didn’t want a seam in the plywood over the 1/4″ gap between the inner and outer box frames of the hatch. So when we installed the 1/4″ plywood around the perimeter of the hatch, it extended several inches inward of the hatch cut-out in the FRP skin that was made during the repower in 1973. Extending the plywood inward left an opening that measured very nearly 4’x8’…just about the same size as a standard sheet of plywood.
To avoid unsupported seams between the 1/4″ plywood around the perimeter and the final 1/4″ sheet in the center, I used strips of 3/4″ plywood as battens under the seams These were also glued and screwed in place.
After marking the frame lines, I drilled and countsunk the holes for the screws that would hold it all together–#10×1-1/2″ for the frames and #8×3/4″ for the perimeter.
The hatch frames themselves are also glued and screwed, wetted out first with 635 epoxy and then pasted together with epoxy bonding agent before being screwed together with #12×3″ screws.
When installing the center plywood panel, I wetted out the frames and plywood with US Composites 635 epoxy, then used wood flour (wood dust and cabosil) as the bonding agent around the perimeter and frames before screwing it all together.
Chris Craft used bronze staples here, but annular ring nails are more readily available today. #8 screws around the perimeter into the 3/4″ plywood battens below hold the edges in place.
The thickened epoxy bonding agent squeezed out just enough to indicate a thorough glue-up.
Since the original Chris Craft approach was only mechanically fastened with staples, the glued and screwed approach should yield a significantly stronger structure than anything that rolled off of Chris Craft production lines back in the day…or maybe even today.
With the frames and a layer of 1/4″ ply installed, the hatch was officially in. On the down-side, for the first time in five years the salon didn’t have a moonroof. 😉
Next up in our 1969 Chris Craft Roamer 46 Refit: strengthening the Salon Roof.