I wanted to summarize this thread with my overall results of using vacuum and heat to dry balsa. 1st is does work, but it is very slow and the drying results are uneven. Areas next to the saw kerfs dry out more than the overall area. There is expense to this technique including the vacuum pump, sealing tapes, films and propane.
The main advantage to the approach is leaving the exterior skin in place to make fairing when you have finished easier. But I think the bottom line in the end is you are going to be doing a lot of fairing after repairing the saw kerfs too. This may be a satisfactory way of dealing with wet core above the waterline, like the area around the exhaust. When the polyester skin is a far gone as what mine is, I don't see the value to saving it anymore.
I think just peeling the exterior skin and getting on with it in the end is the most practical way to get through and as can be seen from the new thread that is where I am with my project now. So the vacuum pump is back in the shop and for some reason it seems to have its eye on the very tired rudder sitting just above it. More on that another day.
