Appropriate Coring for Baitwell and mezzanine floor

Hi all, great site here, first post for me but looking forward to many more! I'm in planning stages for a couple of fiberglass projects on the boat this winter/spring.

The first project is to add two baitwells and tuna tubes across the transom of our 52' Hatteras Convertible. We will be cutting out the existing inboard transom fiberglass and building the baitwell on the inboard side of the transom (inside the cockpit). What core material should be used in this situation? I was thinking 1/2" nidacore/honeycomb. There will be several radius curves in the construction, so I was thinking of scoring the nidacore (or purchasing pre-scored core). Not sure if 1/2" or 3/4" would be best?

The second project is a cockpit mezzanine where the floor on the forward side of the cockpit will be raised and refrigerated storage compartments underneath. We will be using lots of foam insulation to insulate the boxes but not sure what type of core material the top of the deck and hatch lids should be made of. Is nida core ok here too as well? Maybe 5/8" or 3/4"?

Thanks for any input, feedback or guidance. I've done lots of epoxy and fiberglass projects but these will be the two largest for sure, so I'm a novice/newbie, feel free to slap me on the back of the head and tell me what I need!

 

On the mezzanine there will be hatch lids to screw/bolt in as well, not sure if I should use a different core material where the screws will be used or if I should drill and fill with thickened epoxy?

 

Here are a few pics to help visualize what I'm planning. Keep in mind these are VERY rough pics/drawings/mockups.

Here is an old pic of the cockpit when the boat was in the yard last year for repower. It is the only pic I had of the cockpit from this angle to mock the tuna tube install.



Here is a rough comp of what I'm shooting for. Baitwell in each corner, tuna tubes / Bait Socks in the middle.


Here are a few pics of the cockpit mezzanine project.
Cockpit as it stands today:




Some doodling on paper. Hopefully these make sense. This view is from above.


This view is somewhat simplified showing the entire cavity of each hold. Each box will have refrigeration capable of being refrigerator or freezer. The dashed lines are depicting lids.




This is basically what we are shooting for

 

A little more mocking up on the mezzanine

 

I would prefer a higher r value. The better core won't insulate well, but not an expert.

My livewell is i sulated with r10 xps.

I didn't trust it as core for the bottom and used marine foam. I also used marine foam for the thru hull side of the box where fitting will go.

For refer, I would want two layers of r10 or 4" walls. If you have to make tradeoffs, the ceiling and any sides with sun exposure go 4".

If you want to glass the xps, abrade it with 36 grit and hotcoat before glass. Xps won't take much abuse so use 1708 or more in impact areas.

 

Will these be walked on or sat on?

Any I walk on am building with 28# core and 1708 each side.

 

Yes, absolutely. They will be the majority of the flooring on the mezzanine.

 

See my edit.

Am building gutters for my walk ons.

I am building the gutters with 28# core.

 

What thickness are you using?

 

I bought a board of 28# corelite for all of it. The board is about $10/sqft. 20mm or 3/4"

It takes screws well.

A bit brittle; the edges will break if left sharp and not glassed radiuses.

I can take a picture of the profile, but the bad thing is it is deck thickness dependent, so not too universal. The upside is it will stiffen a floor around an opening.

I plan to glass the profile or portions of it like the gutter and the interface to the deck of course.

 

I will also take a picture of the seal, but it is all untested.

 

Mockup no glass no seal on either.

Would prefer a press fit bulb, but couldn't find one I liked.

 

I might look harder for the press in bulb because cutting the kerf now is much easier, but it has to take a corner, too.

 

curious, how are you cutting the kerf?

 

I would kerf the core with a table saw. All the cutting is table saw or chop saw.