Gluing fiberglass/epoxy skin to pvc core for cabin construction

JAT, that is a nice sketch you did above - and I think it does look much better having the two vertical window mullions on the side, rather than having them raked aft.
Although the angle of rake of the front screen appears to be more than the current set up with the canvas enclosure.
On the canvas enclosure you have 'wrap around' corners on the forward end - maybe you can use some timber to mock up the arrangement on the flying bridge to work out first how to build these corners. That should be a lot easier than trying to design it on paper.
Similarly re the strength aspects - generally if it 'looks' ok, it should be ok (in other words if it doesn't look ok, or it looks not substantial enough, then it probably isn't).

 

I think that a clever craftsman could build a one off mold in place, remove it and laminate the entire piece, including mounting flanges, which could then be cut out to suit windows of your choice.
The fiberglass panels mentioned earlier might be a good material to make the mold, and possibly even serve as the outer skin of the finished piece, allowing a rough plywood mold surface.
A few more views of the fly bridge, with the curtains removed would be very helpful.

 

Thanks Bajan. This is all helpful, as I'm designing on-the-go DIY

with no rush to get started yet. I'm now thinking that the 2" frp square tube may be overkill for the side walls so I may go with 1 1/2" instead and go with the heavier 2" tube for the front wind shield pillars and the full height rear wall with doorway. As for looks, the mullions and window frames will probably be painted black anyway like many boats today.

 

Thanks Kapn. I like the idea of making a template, if not a mold, of the wall section and then laminating the wall panel in my workshop, keep as much work (and mess) off of the boat until necessary. Here are a few pictures in the flybridge.

 

What is holding the hardtop up now?

Sure looks nice. Wonder why you are closing it in? Nice extra sleeping room I suppose? Or A/C?

Louisiana! I am considering moving to the Gulf.

 

Come on Down!! The Gulf Coast is great! It's fine here overall but it's a sub-tropical climate. I have A/C in the flybridge and the soft enclosures leak, flex, and are relatively tedious and expensive to maintain. At the same time I find that I hardly ever open them up, and I have a dilemma whether to take the down or leave them up for every tropical storm/hurricane that comes thru -- and there have been way too many of those lately! It's sort of like having a convertible car in southern Louisiana -- you won't be driving it much with the top down like in southern California.

 

As you may discern from a close look at the pictures, the hardtop is a cantilevered built-up structure and has 4 - SS 2" pipe bracing posts (two forward and two aft) bracing it up. It's held up well. I've taken this boat for 500 mile crossings of the Gulf of Mexico at 9.5 knots as well as crossing the Gulf Stream from Florida to and from the Abacos cruising at 22 knots.

 

With the roof designed as such; I would be less worried about the core/hull interfaces.

I like your plan and understand how it would be less headache, cooler, etc.

How will you enter and exit the top? Can you install a door somewhere?