Using Microwaves to Dry a Wet Deck Core

[BubbleHeadMd]

Kristian, this is incredible. I'm certain that I would irradiate myself if I tried it, but it obviously works. It would be interesting to design a purpose-built, microwave drying tool, specifically for boat repair.

[Geminidawn]

Good Idea but you wouldn't catch me being a martyr in the name of better boat building. I heard too many freaky urban legends as regards to people cooking themselves with leaky microwaves.
How I deal with that problem is drill the holes as you said, inject with Acetone to promote vapor and place a 500w Halogen light on the underside which heats the area but not hot enough to bake it. This system is slow and may take a couple of days
After a couple more moisture readings if I'm not replacing the Balsa, I inject polyeurathane foam which need moisture to cure anyway and stiffens the deck up nicely.
Good luck with the experiments, maybe you can develop a way where microwave energy cures osmosis $$$!

[Kristian]

Hi Geminidawn!

I did not know that Acetone is hygroscopic ( hope I got that right??).

It is the same idea that Philsboat did mention that you by using the hygroscopic properties of Alcohol perhaps could dry the core faster.
I have never tried this but will make a small test tomorrow!

If you have got access to Vaccum I would suggest using it since it lowers the boiling temp of water!!

Injecting polyuretane foam is someting I have never tried in a deck.
Is the compression resistance as good as balsa or divinycell?

I have done a lot of gluing with polyuretane glue when forming curved things out of Teak veneer.

As for using Microwaves in Osmosis treatment yes the concept is there but I have not tried it and due to that do not dare posting anything about that one..
Rgds

Kristian

[Kefaa]

I have been reading this with interest as I just (in the past two weeks) had my rudder cut open to dry and restore it. Inside - not a single issue with the stainless - just wet/delamination. So they are leaving it open to the weather (OK - laugh now because it is sitting in front of 30" of snow)

questions:
1. do you have pictures of them doing this?
2. Did they/you shield this area with anything?
3. I was wondering if negative pressure may be of value. Insert a tube of "X" length into the area and a vacuum pump. This would draw moisture away.
4. Do you have a name of the actual equipment they used and what it is typically used for?
5. Did they bill you anything for this or was the fact you let them nuke your boat enough?

I can easily see this answering a lot of issues if the cost can be considered reasonable. Where today we grind out the area, imagine drying it out, open it up enough to inject a slurry if rotted or epoxy if not. (Or maybe epoxy would be enough even if rotted?).

[Geminidawn]

Originally Posted by Kristian

Injecting polyuretane foam is someting I have never tried in a deck.
Is the compression resistance as good as balsa or divinycell?

Well yes you can use regular can of builders expanding polyeurethane foam for a quick fix but it's not very dense. You would be better off to get the two part foam as used in Dellquay Dories and Boston Whalers that'll give you all the structural rigidity you need.

[senormechanico]

Originally Posted by Kefaa

I have been reading this with interest as I just (in the past two weeks) had my rudder cut open to dry and restore it. Inside - not a single issue with the stainless - just wet/delamination. So they are leaving it open to the weather (OK - laugh now because it is sitting in front of 30" of snow)

questions:

I'm glad to hear you don't have any metal degradation to deal with, just cold, wet yuckyness.

One more question:

What would Al Gore use during the "pause" of global warming?

[dpignolet]

I have an area about 18" x 12" that has wet core with some rot right where the water was entering about 4" x 4". I am going to try to use the MAS CPES to repair this, as they claim their epoxy will displace any opf the remaining water. They key is to dry the core. MAS recommends 1/2" holes every 3- 4 inches. I did this in a pattern starting in the center until I found dry core all the way around, since this is a little Harbor and the laminate is so thick (over 3/8" on the top) I decided to do the hole a bit closer together for maximum drying effectiveness.. As you can see i have many holes. I have decided on using a dehumidifier to dry out my core. I put the dehumifier in place and ran a drainage hose first then I build a tent out of plastic sheeting and sealed it off with heavy duty duct tape.I cut a hole in the sheeting for the dehumidifier vent and duct taped the plastic around the edges. Once the dehumidier was turned on it created a nice vacuum inside the tent. After just 12 hour the dehumidifer has removed several cups of water. We'll see how the rest goes.

Once the core is dry I plan on using a low suction vacuum to distribute the CPES through the core by putting vacuum on all the holes that were dry and pouring the CPES from the middle. Once all the balsa is saturate with CPES I will pour west systems epoxy into the holes and use vacuum to pull the epoxy between holes and screw the top laminate to the bottom to compress and re-glue the core to the glass. I'll remove the screws and put 1/2" balsa plugs to replace the core I drilled out, and seal the holes with epoxy and filler.

Note: If the top layer of laminate weren't so thick and rigid already I wouldn't do this fix. The top laminate is 3/8" and the bottom is about 1/4". There is ZERO flex or bounce in the cabin top, even after having drilled all those holes. Since I have nothing to lose, (if it doesn't work then I'll have to cut the skin off and replace everything ). I figured this was worth a shot, a lot less time mess and money.

[Geminidawn]

Originally Posted by dpignolet

they claim their epoxy will displace any opf the remaining water

Check the working conditions of the epoxy, most epoxy resins only have a working tolerance of less than 13% moisture content which means you'll have to get the core really, really dry anything greater and your repair will be compromised. You can get a damp test meter cheap enough from a hardware or if you know a surveyor ask them to do a couple of readings for you.