curing small areas of spongey deck where blasa sandwich has rotted - ideas please

[Burnham Bob]

a friend of mine has a balsa sandwich deck and a couple of small areas of less than a square foot are spongey. i know the 'proper' solution is major surgery, but i had a similar problem with my caravan floor. that is a polystyrene sandwich between two layers of ply and as the polystyrene sags the floor becones spongey. the caravan fix is to inject a 'glue' whch flows into the sagging bit and fills the void, setting solid. the caravan guys also have a 'water loving' glue that sets solid when it flows around ares where damp and water have penetrated sealing the rotten bit solid. is there anything my friend could do with his deck in a similar fashion?

the leaks that led to the rotten balsa are cured and the problem is isolated into a couple of small sections. what do the experts out there suggest?
why can't i edit the header? i dislike showing my incompetence!

 

[john_morris_uk]

Has he got unfettered access to the dodgy deck areas from below?

 

[Burnham Bob]

probably if he removes the headlining

 

[Deleted member 36384]

Chapter 5 of this book http://www.westsystem.com/ss/assets/HowTo-Publications/Fiberglass-Boat-Repair-and-Maintenance.pdf

Although it promotes West products, the method is applicable for other manufacturers.

 

[Bobc]

I had that on my old Jag 25. The surveyor said to drill holes and squirt epoxy into them with a syringe.

I never bothered.

 

[prof pat pending]

Drill plenty of holes in the bottom and squirt in some expanding foam, trim off the excess and fill the holes with gel coat filler.
Probably wise to give it some time to dry out

This is well known problem on Freeman cruisers

 

[charles_reed]

Depends on whether the soggy deck is due to debonding of the end-core balsa or due to it having rotted away.
If just unbonded squirting in epoxy can work, alternatively if it's all rotted, cut out underside side and replace with regular beams (polyester/glass with paper cores).
Using PU foam is a botch which might work but more probably cause even worse delamination.

 

[dave_gibsea]

Epoxy injection worked well for me on an old dinghy sme time ago but remember epoxy hates moisture so if there is any sign of damp it won't work. Make sure the holes you drill are sealed after.

 

[dnickj]

Bob

do you have details on the water loving glue - i could do with some for a small job

thanks

 

[jerrytug]

Bob

do you have details on the water loving glue - i could do with some for a small job

thanks

Me as well, but unfortunately I think it's made-up b0llocks, PVA might be the nearest.

 

[mtb]

Me as well, but unfortunately I think it's made-up b0llocks, PVA might be the nearest.

isn't damp proofing the same thing, I have to re inject a damp proof course around some of the walls in my house
I have dryzone which is a cream in a simple tube you inject into drilled holes along the mortar courses. The cream diffuses into the moister then cures to form a water repellent resin
You can buy it on ebay

cheers
mick

 

[Bobc]

Bob

do you have details on the water loving glue - i could do with some for a small job

thanks

Don't ask me. As I said, I ignored him and never bothered as it seemed like a lot of sodding around anyway.

 

[Rigger Mortice]

Lots of glues are "water loving" in the sense that they require water to cure. Whether or not they use enough water to effectively soak up wet patches is another matter altogether. I don't know the answer but it does sound a bit optimistic to use a glue to dry out a soggy core.

 

[john_morris_uk]

If the decks are dry then inject with epoxy. However if the balsa is rotted then he needs to sort out where the water is coming in first. Once that's done, then he could cut away from underneath and put plywood in place of the balsa and glass over with epoxy. The deck will be stronger than when he started. The ply can be cut to fit the area that you remove the rot from. Some experimental holes from underneath making sure he doesn't drill all the way through the deck!) will find out what is happening.

If its just delamination then injecting thickened epoxy from underneath might be enough. Buy some syringes and its a very satisfying job to do as the results are quick and easy. The balsa MUST be dry and the sponginess coming from the delamination for you to sort it by merely injecting epoxy.

 

[Bobc]

In fact, if it's small areas, what about using the magical CT1 sealant?

Can be used on wet areas, goes pretty damn hard, and you can squirt it in straight from the tube.

Cheap too.

 

[Rigger Mortice]

isn't damp proofing the same thing, I have to re inject a damp proof course around some of the walls in my house
I have dryzone which is a cream in a simple tube you inject into drilled holes along the mortar courses. The cream diffuses into the moister then cures to form a water repellent resin
You can buy it on ebay

cheers
mick

Damp proofing normally just puts a barrier into a wall. It then has to dry out naturally. The barrier simply stops more damp from penetrating/rising.

 

[mtb]

that might have been the case using the old methods of damp proofing
dryzone is the modern method which diffuses with the moister and turns into a resin which is completely different from the chemical mixed with water in the old days
I chucked my old damp proof injecting machine into the scrap pile, the chemical was very expensive ( over £200 ) for enough to mix twenty gallons yet never really cured rising damp in solid brick walls because of the mortar joints

I posted because a question was asked about water activated glue or resin

 

[Ludd]

There is a glue which I used to get called "Gorrilla Glue". When joining two pieces of wood, you had to WET both surfaces first. I used it with dowels on split oar blades---worked a treat!
Whether it would be of use in the context of the OP's problem, I know not.

 

[sailorman]

There is a glue which I used to get called "Gorrilla Glue". When joining two pieces of wood, you had to WET both surfaces first. I used it with dowels on split oar blades---worked a treat!
Whether it would be of use in the context of the OP's problem, I know not.

the same thing to make expanding foam expand more

 

[ripvan1]

Drill plenty of holes in the bottom and squirt in some expanding foam, trim off the excess and fill the holes with gel coat filler.
Probably wise to give it some time to dry out

This is well known problem on Freeman cruisers

Hello Prof another bod from the now defunct Freeman Forum here (what's happening there?)
I tried the injection from below method you advise on my Freeman sidedecks but wasn't too impressed with the results. For the foredeck I removed fittings, carefully cut out the complete foredeck from the top then got to work getting rid of all rotten sponge and using the allen key in drill trick to get under the bits of deck I'd left.
As the foredeck needs to be strong with people traffic, anchoring and mooring strains put on it I cut out 2 x 6mm ply sheets to fit the foredeck and laid them on a sandwich of resin and chopped glass putting weights to get a very slight camber.
Next I put the cut out grp back on top again with resin and c/glass below it and then filled the edges (angle grinder thin blade width) and finally gel coated. Very strong now and thinking of doing same to sidedecks at some point.

Working upside down drilling countless holes is a right pain and makes complete mess inside boat and on yourself I found, and woe betide if you should get that foam in your eye or hair.

Steve