Balsa core issue

[Lightwave395]

I've just had a 'regular' 6 yearly hull survey on my 32 year old balsa cored hull, which I do as a 'peace of mind' excercise.

The report was generally fine, there is a little dampness here and there but nothing (in the words of the surveyor) that would preclude a sale going through were it a pre purchase survey so I'm quite happy with that, however, there is one small area, a section of deck no more than 100mm X 80mm that he suggested was worth fixing where one of the two deck compasses were fitted post build and not well sealed enough.
I've raked out the slightly damp balsa, it's dried out and I'm wondering how best to fill it - do I buy a small sheet of end grain and ram it in, just put epoxy filler in, fill with closed cell foam or what ?

Any suggestions from people with experience most welcome

 

[seumask]

I would not replace with balsa, I would relace with one of the many synthetic foam cores , several thin layers all held in with Epoxy and micro spheres filler. This stuff is all avaialbe from places like east coat fiberglass Buy Composites Core Materials - East Coast Fibreglass Supplies

 

[Hacker]

You could replace with some marine ply suitably wetted out with epoxy first.

 

[anoccasionalyachtsman]

I'd go with the epoxy filler.

 

[Lightwave395]

I would not replace with balsa, I would relace with one of the many synthetic foam cores , several thin layers all held in with Epoxy and micro spheres filler. This stuff is all avaialbe from places like east coat fiberglass Buy Composites Core Materials - East Coast Fibreglass Supplies

The expanding epoxy foam looks like a possible choice - thanks for the link

 

[Spirit (of Glenans)]

I would not replace with balsa, I would relace with one of the many synthetic foam cores , several thin layers all held in with Epoxy and micro spheres filler. This stuff is all avaialbe from places like east coat fiberglass Buy Composites Core Materials - East Coast Fibreglass Supplies

I'm following this thread with interest, as I have a similar problem to deal with. I'd like to know which of those composites would be most suitable for use on a coachroof, if more heavy duty ones are recommended for structural rigidity in larger areas than the OP mentions, whether to use chopped or unidirectional mat, epoxy or polyester, etc.

 

[dunedin]

The expanding epoxy foam looks like a possible choice - thanks for the link

The “expanding” bit might be a worry for me with that application. Don’t want it to prise up or down any of the GRP, leading to gaps in the surrounding deck area which can fill with damp

 

[Lightwave395]

The “expanding” bit might be a worry for me with that application. Don’t want it to prise up or down any of the GRP, leading to gaps in the surrounding deck area which can fill with damp

Probably less of an issue for me, I can use the hole cut out for the compass to inject the foam into the core between the 2 GRP skins and to allow any expansion 'bleed' to escape. It seems like the epoxy foam is a slower and less voluminous expanding material than the usual foam in spray type cans. (hopefully...)

 

[slawosz]

I found very easy to work with this material: Buy 3D Core - East Coast Fibreglass Supplies

 

[blush2]

Our 395 is a year older than yours, we got her surveyed last year because we wanted to change insurers and, like you, wanted to know the condition of the hull. The surveyor's report was much the same as yours.

We had a similar damp patch below a small round hatch in the cockpit. Having raked out the balsa and dried everything it was filled with marine ply and marine filler.

If you decide to use expanding foam, bear in mind it may not be closed cell so will need to be sealed where it is exposed.

 

[Lightwave395]

Our 395 is a year older than yours, we got her surveyed last year because we wanted to change insurers and, like you, wanted to know the condition of the hull. The surveyor's report was much the same as yours.

We had a similar damp patch below a small round hatch in the cockpit. Having raked out the balsa and dried everything it was filled with marine ply and marine filler.

If you decide to use expanding foam, bear in mind it may not be closed cell so will need to be sealed where it is exposed.

Yes, thanks, apparently the epoxy foam is closed cell but I'll be sealing the edges in any event just to be sure - there was a Blush with a red 395 hull and a fractional rig in Hamble a few years ago, is that you ?

 

[blush2]

Yes, thanks, apparently the epoxy foam is closed cell but I'll be sealing the edges in any event just to be sure - there was a Blush with a red 395 hull and a fractional rig in Hamble a few years ago, is that you ?

Yes, that's us. I recognise you as well, you've got a tiller I think? Sorry I can't remember your name. We've moved to Devon. It's a 395 hull but finished by the Stewarts in collaboration with Carl Schumacher, the original designer.