Interesting quick fix on soft spot on deck

[Sailorman Ed]

Downwinder - I was also a newbie at this about a couple months ago but no more. I am in the middle of replacing all of the balsa in my salon walls.

First, you must find the source of the leaks (if you have one, you likely have several) and stop them. See the excellent write-up in MaineSail's page on how to properly seal mounting holes. Some of the balsa had turned almost to powder, some just falling apart and some looked good but had lost the adhesion to the outer wall. Be brutal, take anything questionable out. The balsa between the layers stayed wet for a long time. then I took a large wire wheel and cleaned the surface as best I could.

Next (and I am not saying this is the best way), I laid out the new inner wall on a sheet of PE film on the salon table, cut out the new balsa, glued them up and let them cure.

Then I mixed up some thickened epoxy, spread it on the new balsa and clamped it up in the window openings, using longer 2x2s to keep the now quite flexible walls straight. After curing, they are quite strong and with the inside finished surface nice and smooth, turned out well.

The decks will be the last area I tackle, I wanted to get good at this first as all of my decks have a curve to them. I do not think there is any quick easy way to do this correctly!
Ed

[Stu Jackson]

Originally Posted by biker6977

Coemj- you could have easily ignored this thread and made no comment. Once you read the OP you can have just clicked off of it. I'm sorry if us newbies do not know all- I thought that's what the forum is for. At least that's how I use it to gleam knowledge from those that know- you obviously being one of them. We've not all read all the books or done all the work. I'm always looking for better ways to do something and without asking and finding out the reason something won't work from someone that has tried it I just don't know if it will work.
So instead of getting snippy and tired of us understand we want your comments- constructive- and why it won't work, who's tried and what the results are. We are here to learn from those that know.

Not snippy, simply true.

There's a reason that "tried and true methods" are called just that.

That foam also expands and could well simply lift the deck above.

NOT a good idea.

If it was, it would be the "tried and true method."

[a64pilot]

This method may from one way to repair a void in aircraft honeycomb structures, you drill several holes in the honeycomb and fill the void with adhesive, probably an epoxy.
Of course extensive voids you do just like a boat, remove a skin, remove and replace the core, bond the skin back down, but small "voids" in non critical areas, you can "shoot" with epoxy.

[Scaramanga F25]

I have drilled from the top at intervals and used an allen key in an electric
drill chuck to shred and scoop out wet core.
When blow dried I used an epoxy filler.

[valhalla360]

Even if it's rotted, I can't see it pushing all the rot out the other holes.

Also there are different density foams. The stuff in the spray cans is generally lower density and not strong like concrete. The structural foam typically comes in a two parts that you mix together and poor into a space.

[onestepcsy37]

Originally Posted by downwinder

Balsa is rot so im guessing its powder rot wood. Foam will push out whatever it can and fill up all space with its expansion characteristic. Its light and strong. It will fill up whatever hole in the railing/gunwhale that is letting water permiate inside the core.

If it really does turn to powder you might be able to vacuum it out through the holes you drilled. Then the foam might fill up the space. I cant imagine the foam pushing the old core out through the holes. But I have no experience with cored decks; CSY only built solid glass decks.

Why dont you just drill some "exploratory" holes and let us know what you find.

[Tibor]

I'm currently doing a complete refit and mostly because of a soft spot or two which have been cut out and repaired properly. My advice is to ignore what can only be a temporary fix that does not address the problem and do the proper repair. That way your problem will not spread which will make the repair much larger and more costly in the long term if you shortcut method is used.

[Cadence]

Originally Posted by Tibor

I'm currently doing a complete refit and mostly because of a soft spot or two which have been cut out and repaired properly. My advice is to ignore what can only be a temporary fix that does not address the problem and do the proper repair. That way your problem will not spread which will make the repair much larger and more costly in the long term if you shortcut method is used.

[Stumble]

Ignoring for a moment all the other reasons...

Of the four physical qualities when selecting a core (compressive strength, shear strength, weight and cost) lets just look at compressive strength.

Gurit 110 balsa core (its lowest strength core) has a compressive strength of 1460psi. 16lb two part urethane foam (the highest density and strongest normally available) has a compressive strength of 580psi. 2lb density stuff like you would find in a can has a compressive strength of about 40psi.

So how do you take a highly engineered structural component like a boat deck, remove 2/3 of its compressive strength and expect it to work properly.


Of course who knows when you inject foam into a void if it actually fills 100% of the space or leaves voids. And the bond strength of high density foam is a joke, and you still have a bunch of rotten wood and water in the space. But sure go for it. What could go wrong.


As for rejecting any advice from anyone who hasn't tried it... I haven't jumped out of a plane without trying it either, but would recommend against doing so. The same logic applies.