Cabin Roof and Bathroom

Composite Roof Experiment...

1/2" Ply edge buildup

 No guts no glory right? The original plan called for a tripled 1/4" plywood buildup for the roof.  Problem for us is that we want some insulation in that roof and we have some swanky little recessed LED lights that we want to install in the roof of both cabin and pilothouse.
So to accomplish this we need to build it up like a sandwich with edges that can be shaped.
We ripped 2" strips out of 1/2" marine ply and simple epoxied and screwed them along the edges with plenty of overhang so that they could later be "flushed" with the cabin sides.

First layer glued and stapled down with 5/8" narrow crown staples.
Note the epoxy poured out ready for the second layer.  Stagger the seams.

The next decision was what kind of insulation? I knew that one source of information may be the surfboard community and I spent a little time on a few forums where builders expounded on the virtues and pitfalls of the two main types of ridged board insulation, Polyisocyanate and Polystyrene.  Polyiso for starters can be though of as what is commonly used in spray foam for home walls or the canned foam used to fill cracks and voids around doors and windows.  This isn't entirely accurate but they are all pretty similar.  Polystyrene, and specifically extruded polystyrene, is the product used in building construction usually referred to as "pink" or "blue" board.  I opted for polystyrene as I am gluing all of this together with epoxy and it is locally available.  Polyiso carves better but is harder to find un-faced (typically comes with foil face locally) and I am not carving this.  It will live between two plywood skins and only serves as an insulating core.
The Owens Corning product came with a plastic skin that had to be peeled off before gluing.
Two layers of sheet insulation went down easy.  I used a narrow crown stapler to secure each layer starting with 5/8" for layer one and 1" for layer two that I bounced hard off of the foam so that it recessed enough to grab the ply below.

2-1/8" recessed light holes bored from the inside

Now, all was allowed to setup good and hard.  The lights needed a 2-1/8" hole to mount and we crawled into the berth and measured from the walls to layout a pattern of lights that would avoid the future hatch and Dorade vents.  Once bored with a hole saw it was back to the outer foam surface to route channels to fish wire, daisy chain fashion, from light to light.

Port side

 The grooves were just simple routed with a 1/2" straight bit about 1/2" deep.  Nothing special in guiding it or jigs.  It routes without any resistance except for the occasional staple that get struck and mangled.  Startling but uneventful.  We just picked them out.  We used 3/8" pex pipe for the conduit.  Channels alone would get filled with epoxy as the outer skin was laminated.



Starboard. Note the Pex sticking up around the pilothouse.
Had to be heated and bent to the groove.  The opposite end
is drilled through the pilothouse behind the future location of the
instrument panel (and DC supply panel) at the helm.

Scribed to the windshield and clamped to be marked along the cabin sides.

Now comes the outer skin and it was a learning experience. First it is a curved surface laying against an angled windshield panel.  I have seen other builds that basically started the windshield panel above the cabin roof but I thought it left hard angles that looked strange. Definitely gave the impression to the viewer that intersecting curves were scary to the builder. The answer is simple, use a compass.  Mine is one of those Lee Valley multi jointed affairs but just about any kind will do.  Run your plywood hard against the windshield, set your compass to the widest gap and run it from one side to the other. Cut this and take it back.  Clamp back down and mark along the outside edges.  Now piece number one is ready, number two is easy. But it to the first and mark.

Every ratchet strap I own... Need more for the pilothouse...

The assembly was the sort of frantic, "Oh hell!" part of the build that my wife walked in on. I ran spastically around the boat, cutting clamping cauls to spread the pressure and constantly readjusting.  I thought that I would simply pull it down and screw the edges, nope... It left the center of the 1/4" marine ply panel with little to no contact with the adhesive.  So, I energetically sprinted around the boat as clamps slipped their hold and visions of solidifying epoxy raised blood pressure.  The wife walked in with a question and I immediately responded with a God d*** that let her know I was struggling.  She immediately grabbed the strap ends and held them as I built pressure on the panel and adjusted pressure.  Advise to all, if you do this sort of thing, line up some help.  Everything is slick and at some sort of angle that ratchet strap hooks don't like.

The end result seems solid.  It allows for the lights to be installed that seem unobtrusive and should add a real custom touch.  I intend to install a dimmer for both the pilothouse and cabin so that light can be adjusted to provide just enough for getting around without making us night blind.  The pilothouse roof will be an even larger challenge due to size and height.  We went ahead and installed the first layer to get it along as far as possible before moving this outside to be finished.  Not permanently, so we will devise a method of rolling or skidding it in and out.

The only noteworthy mention regarding the first layer of beadboard on the PH roof is the mahogany beam cut and installed.  Not structurally necessary, it nonetheless serves as a way to hold the proper shape for future layers to come.
Of course, some of this build is out of sequence as I post it and I am trying to lump similar portions together.  In reality we have moved around and prior to attaching the roof panel we had to install the bathroom walls as the roof panel joins to the wall.

 

Ship's Head and Shower

Hot glue and cardboard pattern

One layer installed.

You'll remember our plumbing the shower sump a few posts back.  Now we frame that in and make ready for the foam fill that will follow in a subsequent post.  We start with a paper pattern of the two additional layers of ply laid on the floor.  This is to gives us enough thickness to install a proper drain grating 1-1/2" thick.  Once the pattern is cut we epoxy and screw these down and begin layout of the long wall.

Doubled Beadboard glued and cut.

The long wall incorporates a door and will have a "show" face on both sides so will need to be laminated from two
beadboard panels.  The door is cut and this wall panel was taken to the pilothouse to be scribed to match the subtle differences in angles inherent in boat construction.  We shoot for a tight fit.

Toilet will fit into recess.

The remainders of the walls were a "try and fit" situation (better known as boat building) as subtle differences in floor to wall angles caused us to adjust and scribe.  They weren't enough to worry about and aren't noticeable until you mate two right angles together.
I did opt to create a shelf in the bath that is basically the largest dimension I could hold on the width below the hull's sheer line. 
The entire room will be coated in multiple layers of resin before painting with marine poly tinted white.  All corners and joints will be filleted and smoothed to completely seal.  Now that this is done, its time to foam the hull or as I think of it... 30 gallons of life insurance.

View looking into the bath and shower.