J/30 Class Association Forums J/30 Forum The Boat, Sails and Equipment Hot Vac Hull Drying, Anyone tried it?

Has anyone tried using the "HotVac" system for drying a wet hull? I ran across the information using an ask.com search. The link is; http://www.hotvac.com/
A local yard here in the Portland Oregon area has one and claims it will dry a wet area on a hull or deck in 7 to 10 days.
Just like the vacuum bag process except constant, even heat applied at about 100c.
"...the unique system uses heat and vacuum to vapourise acids and glycols that cause the osmotic problem in the first intstance... "

I looked into the hot vac system for drying out my boat which had/has the starboard side wet core issues that seem to be a recurring problem on the J-30. I was told that it would not be a good choice for my boat because it is really designed to suck moisture out of the laminate, not the core. If your issue is blistering due to moisture in the laminate the hot vac system may be a good option but if your moisture is in the core probably not.

Thanks for the reply. Can you direct me to the source of your information. The owner of the yard here said it would dry the core, so I would like to here the reasons why it may not work.

The guy I was using at the time was Steve Uhtoff of Annaplolis Gelcoat. Steve has a bad back and is now out of the repair business and into surveying. His cell phone # may still be good thoug it uis 443-336-3560.

I know a couple of guys who have had their balsa core boats done Anchors Away BoatYard in N.C. and are very pleased.

Follow-up;
I took Rauzer II #448 to the boat yard end of March for bottom paint and estimate on drying the wet spot on the hull bottom. We mapped out the wet area with moisture meters. The area was on the starboard side measuring 42" fwd of the keel to 54" aft of the keel, almost 13 feet and 32" up from the keel fwd to 42" up from the keel aft.
The yard manager gave me a reasonable bid and said the job could be done in 2 to 3 weeks so we decided to go ahead and have the work done. They peeled the area, set up 2 pads and started heatind and sucking out the juice. It was bringing down the moisture levels however when it rained they claimed they were pulling bulk water. Meaning rain water was making its way into the core. We put food coloring in the bilge which had just a few puddles of water and around the mast step where rain water from inside the mast accumulates. Again they claimed they saw evidence of the dye in the moisture they were pulling. Since I was out of town at the time I could not verify this.
After a couple weeks of using the HotVac machine it became impossible to get a vacuum on one of the pads so it was determined there was air being pulled from inside the boat. The moisture meters indicated some improvement but no where near dry enough so we decided to cut the outer skin and replace the core. This was done in 4 sections. Cut out one big square skip an area and cut out another big square. The core for the most part looked really good, however closer to the keel there was some sign of spore that would have eventually caused rot. As the core near the keel was pryed out it would actually drip a little water. There was significant dry glass fibers and the smell stunk up the whole yard.
The inner skin was very thin and under the cooler it was so thin that they broke through exposing the bottom of the cooler. We cut out a small section of the inner skin under the cooler exposing the foam insulation which was black and had obviously been very wet at some time though it was dry now. The cooler drain and hose looked good so it looks like the channel where the hose goes to the bilge allowed water from the bilge to fill the void under the cooler when the boat was heeled to starboard. Either that or it was from condensation from the cooler itself.
Once the first two sections were cored and glassed they cut out the remaining two wet sections. This is where it turns out the wettest core was found. As we dug out the core next to the keel the very wettest core was a few inches aft of the front of the keel which is pretty much under the mast step and the front of the bilge.
As luck would have it, I took a picture before the repair from inside the bilge looking forward since I wanted to see how water from the head area made its way to the bilge. After the repair was done I took another picture and found that some of the sealant they used for the repair was forced into this area. This was located at the very top of the bilge where the hull meets the keel mount.
Conclusion: The wet area had not grown since the survey 3 years ago. The previous owner had an automatic bilge pump installed but before that the bilge was often quite full since it had to be manually pumped and here in the rainy Northwest lots of water makes its way into the boat via inside the mast. Also water from the mast step drained past the area that had a path to the core so when the HotVac was sucking and it rained, it pulled some of the rain water. Even if the HotVac had dried the core, it would have gotten wet again over time since the source of the water was not known. It took several coats of faring material and grinding to get the hull shape right but they eventually got it and we put the boat back into the water yesterday, May 24th.
In hindsight, I should have waited until fall to do this since I missed the early season races. I cannot wait to put the sails on and have some fun. I wish I could have spent the money on new sails, something I could actually see and enjoy, but at least my mind is at ease knowing the hull is sound and dry.

Great update! What kind of moisture meter was used when you did the measurements? Can you provide any moisture mapping info (readings/position)? Having launched last month after completely stripping the bottom to gelcoat (couldn't see any blisters), new barrier coat and VC Offshore, I'm not real keen on wanting to look for problems, but on a boat 25 years old I know better. This would be a project that would start with measurements in the fall after hauling for the season.

We used primarily an Aquant that reads from 0 to 999 that has lights that range from green to yellow to red as the moisture level detection increases. Most of the boat was safely in the green but the wet area was all in the red and the numerical reading went from 400 to pegged. We also used an analog moisture meter that read percentages. Most of the boat was at 10% or less and the wet area went from 15% to pegged which was over 30%. As far as mapping, re-read the above first couple lines.

Just curious-what was the cost of the whole procedure?

The yard graciously deducted the time spent on the HotVac procedure. The whole deal including 2 gallons of VC Offshore for the final coats came to almost 70 boat bucks.
(1 boat buck equals $100) ;-D