Repairs to balsa cored deck

[lumphammer]

Repairs to a crack at the mounting point of the lower shroud have turned out to be more complicated than first thought. The crack has gone through to the balse core which is now very wet and rotten in the area of the crack.

Any suggestions on the best way to repair, gratefully received. My initial plan is to drill holes over the affected area and break out the balsa with the old bent nail, then inject epoxy + filler into each hole.

Any other thoughts?

PS the original movement has been sorted (I hope) with several layers of grp mat and a bigger backing plate under the U-bolts

 

[rob2]

That sounds about right to me, based on all I've read over the years. The given methods for delamination of cores in both boats and caravans (oops, my weakness showing) is to inject epoxy. Removing the affected core is essential with balsa. I would suggest a good, bulky, lightweight filler in the injected epoxy.

 

[Poignard]

Well described in the WEST epoxy company's guides, available from Wessex Resins Ltd, Romsey. I expect there's a website.

 

[PIGLETSDREAM]

This was a common problem on Trappers and probably many other yachts, but as a former Trapper 500 owner feel able to comment. Our repair was
1. Expose a hole of approx 2 inch diameter
2. Put a bent nail or something similar into battery drill
3. Gouge out a bigger area than the damage
4. Fill with epoxy
5. Re drill hole for chain plate
6. had a stainless plate made up and attached to chain plate so as to spread load and fitted new oversize backing plate.

Failing that follow the instructions on the West web site under replacing a balsa core

 

[oldsaltoz]

[ QUOTE ]
Repairs to a crack at the mounting point of the lower shroud have turned out to be more complicated than first thought. The crack has gone through to the balsa core which is now very wet and rotten in the area of the crack.

My initial plan is to drill holes over the affected area and break out the balsa with the old bent nail, then inject epoxy + filler into each hole.

PS the original movement has been sorted (I hope) with several layers of GRP mat and a bigger backing plate under the U-bolts

[/ QUOTE ]

G'day Lumphammer,

When repairing a Balsa deck that has a leak near a fitting it is most important that the Balsa remaining in the area is very dry and, that the material used to fill the void is strong enough to resist crushing.

Just injecting resin will only work if the balsa is dry and all you want to do is improve the bonding between balsa and layup.

Adding Micro-Balloons and epoxy is not a good idea in an area that will be under some stress, particularly compression between fitting and backing material.

Using Micro-Fibres or even 'very tiny' bits of glass trimmed off a sheet will provide a solid crush resistant mass that will also help prevent further moisture entry if mixed to about toothpaste consistency and prewetted with a small amount of resin and hardener, this helps in coating the outer extremities of the repair.

Any deck that is not solid GRP and contains any material that may suffer from moisture contamination should be drilled oversize, filled with a suitable filler as above and re drilled to the required size. this includes Balsa, ply and composites.

Any epoxy repairs MUST be DRY before any resin is applied or you are wasting time and money.

I hope this helps.

Avagoodweekend......