Vacuum Pump to Dry Core ?
 

Has anyone used a vacuum pump to dry out, via evaporation, a small area of core to prep for epoxy ?

I have a small area in the bow/deck of my 23' Tsunami, where one of the SS rail, deck-base screws leaked into the core a bit ( the one area I did not pot with epoxy !!! ) I'd rather not cut the non-skid and doing from the bottom is nearly impossible due to access.

I've read that this is an effective way to dry out core via vacuum and evaporation.

Anyone been there done that ? Recommendations on the pump and process ?

Thx.

Nope, but heat and denatured alcohol can be your friend.

Just had a thought...dangerous, I know.
What about kosher salt?
This is how you cure fish and meat right?
The salt pulls the water out due to the salinity difference between cell walls.
Osmosis.

Vacuum will work; there was an outfit on Ship Shape TV recently (I know, I can't stand Griviskis either! He'll peddle anything if somebody gives him free stuff!). There is an outfit that does this commercially on big boats for big bucks. If you search the SS TV site, you might find something about it. I have used denatured alcohol and IR heat lamps and that works also.

With most vacuum pumps - even fairly high vacuum ones, you can't get the pressure quite low enough to boil the water out. At 80F the boiling point for water is 29.92 in of mercury (or 0.49psia) - it takes a REAL good (and expensive) vac pump to get there. However, with vacuum you may be able to increase the evaporation rate of the water from the area and move a bunch of air through it to improve drying.

Realistically, if you have water, it may be larger than you hope.

Thanks for input, guys. I have a small non, structural area near the forward bow rail stanchion that leaked water through the re-bedding job I did 12 years ago. I want to pull the fittings and let it dry out. I've heard about the vacuum / boiling water out idea and thought it just might work - coupled with alcohol and a heat lamp, drill/allen key core removal. The salt theory, is funny ( I hope you were joking !? ), is saved exclusively for when I brine fish and venison ! :)

I read somewhere that you buy a good air conditioning vacuum pump, drill a hole for a schrader valve ( tire tube filler ), connect vacuum and let it boil the moisture out. It sounds logical, especially in a small area.

I also agree that the wet will be more than I think. Anyone who has played around with re-coring has to assume that ! Water and core are a marriage made in hell !

Any ideas how a DIY'er might go about this ?

I would hate to cut the top nonskid/ deck out to access the wet core to repair this the right way… I've had as much re-coring as I can take.

Me??? Being a whack job??? I see you don't post much...
Salt has been around as long as dirt. If it worked, Noah would have told us by now.

I do enjoy asking Denny why the earth spins whilst being in an atmosphere tho...

Huh ?

Yes, I was being funny.

Aaah. Got it. So... about the vacuum pump idea ?

Am I ' pissing into the wind ' or will this work for a small area ? And, if it does, and I can dry her out with alcohol, salt etc… What would be the best epoxy, resin that would flow into the dried core and make it solid ?

Again, not a traffic area, but me no-likey wet in 'da core...

vacuum pump will help, but I dont think I would go buy a pump just for that small repair. I would use a drill to remove as much core as I could through the hole, then fill it with epoxy.

I assume boat is stored for the winter up off Lake Erie. If there's water in the core, it'll be a lot softer come spring due to freeze damage! I agree with both Flexpat and Shine, the vacuum will work but it will take time; if you heated the deck AND could pull the vacuum on the core down below the boiling point, the water would theoretically flash to vapor immediately. However, even if you can't reach the flash point pressure/temperature conditions, water will still evaporate, only it will just take longer. You could probably figure out how long it would take to evaporate all the water but it would be a complex calculation involving dew points, relative humidity and psychometric tables, etc.!

If boat is laid up for the winter, time is the one thing you have plenty of! If boat is under cover or shrink wrapped so rain/snow can't get to the deck, I would drill some holes in the soft area and soak it with denatured alcohol. That should prevent freeze damage, and help dry it out as the alcohol will combine with the water and then remove it as it evaporates. But if boat is shrink wrapped, make sure it's well ventilated! If it's well sealed nothing will evaporate! If you repeat the soak/dry cycle several times over the winter, it should be fairly dry come spring, when you could soak it with Git Rot, which is very thin and penetrates rotted wood real well.

OK Guys. Thanks. I am shrink wrapped and have along cold winter ahead. I'll try to use the holes that the rail mounts to the deck with as breather holes. I'll do the alcohol/ heat lamp first and see how that goes.

Git Rot - I've heard of it but never used it. Is it an epoxy based material ? Does it fill all the voids and solidify ?

Located on Long Island - The boats in the Lake Erie area must turn into literal ice cubes each season. Cold up there !

Yes it's a very thin epoxy; the idea is that rotted but dried wood will soak it up by capillary action, and it will then solidify. Kit comes with a squeeze bottle with a separate bottle of hardener. I don't think standard kit is more than about 6-8 oz., so might be worth calculating how much volume you need first. You can probably buy a low viscosity epoxy from other suppliers such as Jamestown Distributors or our own Shine for less.