Solid laminate deck/cabin roof

[andyj301]

I currently have a Halmatic 30, the cabin roof and deck is about 25mm thick solid laminate. Could anyone tell me of larger yachts approx 35' that have the same construction?

 

[jwilson]

I don't think a Halmatic 30 actually has a solid GRP cabin roof and deck 25mm thick all the way round. There is an inner moulding giving a smooth interior to the coachroof and cabin, but I really don't think it's solid. I doubt if any builder would deliberately use that much laminate thickness, or any designer specify it. There may be some areas with what ends up appearing as 25mm solid, but not that many.

 

[andyj301]

I've made a couple of sizable holes within about 0.5m of mast step, approx 115mm for Refleks flue and 35mm for swan neck, they both revealed solid core, no balsa. It maybe some other kind of core that soaks up the resin? Perhaps boats that are not balsa core deck would be a better way of phrasing the question?

 

[Ammonite]

If it is solid laminate I imagine thats part of the compression post / cabin strengthening arrangement to help support the mast in that area?
You can also get something that appears solid at first glance but is actually a bit like an aerated / lightweight resin (rather than balsa or foam) between two sheets of fibreglass. My Nebe Cape 28 uses this but I cant remember what its called. The good thing is its water resistant (no soggy cores) and you dont need to hollow it out and fill with epoxy when adding fittings.

 

[andyj301]

You can also get something that appears solid at first glance but is actually a bit like an aerated / lightweight resin (rather than balsa or foam) between two sheets of fibreglass. My Nebe Cape 28 uses this but I cant remember what its called. The good thing is its water resistant (no soggy cores) and you dont need to hollow it out and fill with epoxy when adding fittings.

Thanks, that maybe what I'm looking at.

There seems to be 5 layers, the inner layers can just be marked with a knife and good deal of force. It's a 40+ Yr old boat so whatever core materials were available then. I've also rebedded tank inlets on side deck, looks the same construction. The most important thing for me is not balsa, I'd rather avoid the risk of having to replace a spongy deck if possible.

 

[Ammonite]

It looks very similar to my Nebe which is from 1982 although mine is not as thick. Perhaps 12 - 15mm but with stringers on the larger deck sections and wooden ribs / decorative batterns on the underside of the coach roof. It will feel a lot lighter than a similar core from the hull if it is the same, not that I'm suggesting you should go and drill unnecessary test holes!

 

[SteveAus]

Can you weigh the cut out core? If it is fibreglass laminate its specific gravity should be 1.4 or higher.

 

[andyj301]

Thanks for replies. I divided weight grams by cc, came out around 1.28 so not solid laminate. But also not balsa.