Hi , since this forum is about sharing I hope that there might be someone that can use my approach on how to dry a core
in a cored deck
I did find a slightly "spongy" area on my foredeck and did find out that this was due delamination
of the sandwich construction and that the balsa wood that the core
was made out of was wet.
This of course had to be taken care of and the traditional approach with cuttting the top layer away and replacing the core material did not feel inviting.
I started to sort out the problem by learning
more about GRP.
This material was invented to get an aerodynamical enclosure in front of the radar antenna
in fighter aircraft.
This information together with the question on how to get energy into the water
in my core to boil it away lead to the hypothesis that microwaves since passing through GRP would be ideal.
I contacted Munthers that is a big company using different drying methods and they got interested enough to send two technicians with neccesery eqpmt. to measure and verify if it all worked out as planned.
The drying worked absolutely perfect and the only drawbacks were that you had to drill holes to the top laminate to allow the water
vapor to escape quickly enough and the other that you only got heating
directly beneath the magnetrone covering the size of approximately your hand.
The drilling of holes was no problem since I had planned to inject epoxy
pressurised by an Airgun to glue the dried core back to the top and bottom laminates. ( The drilled hooles penetrated the top laminate and went throug the core but not the bottom laminate)
The smallish area of heating
was annoying and it took a few days to find a remedy. The problem was that the microwaves passed directly throug the deck
and only a small part gave of their energy to the water in the core.
I figured that if I did put Aluminum
foil onto the inside of the deck I would get a reflexion of the Waves back up throug the deck and another reflexion inside the Microvawe own down through the deck and so on and so on.
It worked perfectly!
The heat distribution was perfect and using an old household Microwave Owen with the bottom sawn out and front door permanently fastened it was easy to use time and " power" settings to get the drying done unattended.
( The deck must never get hotter than some 65deg Celsius othervise you risk deformation since the GRP is getting softer at about 80 deg C and due this it is best to use longer run times with less energy added)
I found that a lower setting for aprox 20 minutes dried the area covered ( aprox 40X25 cm).
Once dry I injected epoxy
under 7 kg/ cm2 pressure into all holes. To make the top laminate both stronger and totally watertight i layed two layer of 250g/ M2 cloth over the total area mended.
The problem with getting the nonskip pattern back is another story but really not impossible only add more work...
The end result is a deck with the feeling of that it now is made out of pansar from the Bismark! And yes it is just slightly more heavy than the original deck but it is really negliable.
Finally I have to add a strong warning about that yau have to be aware af safety prcautions when working with microwaves.
Leaking microwaves can cause hotspots in your body that can cause serious injury.
You have to buy/ rent a microwave detector with varning functions showing if you are exposed to too much energy. I used one of these and found that if I in addition to the Al. foil under the deck also covered the gap between the deck and the owen I could get this almost microwave tight ( like your owen at home)
If interested do not hesitate to ask questions and please use this method first after you understand the hazards involved. As with many efficient methods if the dangers are understood and managed the safety aspects need not to be a problem but if ignored they will be a problem and you could get injured.