Nidaplast Hardtop Laminating Schedule

[jacquesmm]

For the foam, in this case, 12mm and 15 mm as core are interchangeable. 12 mm (1/2") if fine for the superstructure but for years, we had the 15 mm in stock for the same price than the 12 and sometimes I specified 15.

I can calculate the weight savings. Just for the cabin top, there is no significant weight difference because I would specify 1/4" plus glass. If all bulkhead's and sole were made from foam sandwich, we could save 200 lbs or more. The main reason to use foam is not only some extra stiffness but above all insulation and condensation.

[Tom S.]

Sounds great thank you very much for the insight.

[Tom S.]

If the weight savings in the top alone are negligible is there any insulating benefit of nidaplast?

[fallguy1000]

If the weight savings in the top alone are negligible is there any insulating benefit of nidaplast?

Some.

Anytime you have an air gap; you get r value. How much?

I do not know. Some guesses. R value of a 1/2" double laminated 6mm ply roof on the order of say 1? It is documented somewhere. I suspect the r value of an inch of nidaplast is a bit less than an inch of polystyrene. Say on the order of r-3.3.5?

In my roof, I will get the 12mm core and the ply and a 1.5" air gap with 4mm ply.

Where do you plan to sail? I will give you an honest opinion about what I would do based on thermal expectations and any heat/ac plans.

[Tom S.]

Northeast, cape cod, day tripping only. Not really concerned about heat loss or cooling just condensation.

[fallguy1000]

Definitely a valid concern...

In my build, I am nervous about drips in my fisherman's bunks which are 12mm corecell sandwich. If I have trouble, I plan to use armaflex sa. SA as in self adhesive.

Another thing to keep in mind is air movement in the cabin. If you have fans inside the cabin; it will reduce drips. I think Armaflex would be a good backup plan if you are unhappy. Keep in mind condensation happens warm in high rh cold out. Air gap is always best. For my main cabin, I have 1.5" beams and plan a 4mm ply headliner. So I will have a pretty good air gap and some r value above from the san/ply.

I think the armaflex has 1/8 seam tape and you can cover the seams. If you don't like the look; I was thinking thin varnished wood strips, but anchoring in nidaplast or plascore would be a pita. Not sure..

Hope I am at least provoking thought and not jist provoking. The boat will be really special when done. You could also use the nidaplast roof and then fur down say 1/2" and epoxy glue those strips to the nidaplast, pick up an airgap and a place for wires and headline with say 4mm okume or formica wrapped in vinyl...see sailrite headliner vids..the 4mm okume could also be painted as I intend. It comes in at 13# for 32 sqft or about .4625# per sqft plus your furring strip and some paint and a trimmer..

[Tom S.]

Thanks fallguy yes very thought provoking, which is a good thing.
I believe I’ll stick with the 1/4 plywood top with a couple more ribs added like Wes K did on his GT27

I also have access to some finished sound dampening decorative panels. They are similar to an aftermarket product that they sell for the interior underside of Jeep Wrangler hardtops. They are easy enough to add later if needed.

[fallguy1000]

That is a great look and gives you options if you have dripping.