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Vacuum pump sucks water out of board!! Thank you Boardlady!
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thombiz



Joined: 25 Jun 2007
Posts: 556
Location: Corpus Christi

PostPosted: Sat Oct 26, 2013 6:54 pm    Post subject: Vacuum pump sucks water out of board!! Thank you Boardlady! Reply with quote

I lent my board out and it came back with water in it. At first, I took 2 large black plastic leaf bags and taped them together to make a large long black bag/condom. I slid this long black bag over the nose and down to the tail so that all but 15" of the tail of the board were sheathed in the black plastic bag. I used masking tape to bunch up the excess of the bag, so the bag was tight to the skin of the board, then I put it out in the bright sun to heat up, leaning it against a fence so that the vent plug/drain was at the lowest point Bag surface probably got to 160 degees F. or more after about a hour in the sun. I took out the vent plug and used a rolled up paper towel stuck in the vent hole to wick out the water which would collect at the vent plug/drain. Over and over, the paper towel would get wet and I'd replace it with a fresh new dry paper towel wick.

Ok...after 5 days, I had most of the water out, but I still could dampen a single paper wick in a day. Then I remembered something I read years ago on the Boardlady's website. She wrote "hook up the vacuum pump to the board and let it run all day". I've always been a sceptic, but I had to give it a try, so I hung the board from the ceiling, hooked the hose to the vent plug in the board, and set the vacuum pump on a table so the hose between the vacuum pump and the board would have a low spot to collect the water to keep it from going into the vacuum pump air tank.




I then turned the pump on and set the pressure level to 15" Hg (7.36 psi corrected) and at about 10" Hg, water droplets started to come down the hose, one droplet every 5-10 seconds. In ten minutes, I collected about 4 tablespoons of water. The clear hose is nice because you can see the droplets, and you can see when to turn the pump off and drain the hose.



Thank you Eva Hollmann, this works great! I'm going to let it run until no more water comes out!


Last edited by thombiz on Mon Oct 28, 2013 8:22 pm; edited 2 times in total
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thombiz



Joined: 25 Jun 2007
Posts: 556
Location: Corpus Christi

PostPosted: Sun Oct 27, 2013 12:35 am    Post subject: Reply with quote

After running the vacuum pump for several hours, the droplets of water coming out of the board ceased......so, I shut off the vacuum pump and unhooked the hose to the board. I let the pressure inside the board equalize for about half an hour then I hooked the vacuum pump back up and turned it on. Almost immediately, droplets of water started coming down inside the hose. I think what was happening was the vacuum pulled on the board, squeezed the board forcing the water out of the styrofoam, very much in the same way you squeeze a wet sponge and water starts to come out of it. This is not what the Boardlady was describing. I paraphrase what she said "the reduced atmospheric pressure inside the board will pull out the water molecules from the styrofoam in very much the same way that water boils at a lower temperature at high altitudes". The problem I have had in the past was...once the water molecules are in the "air" inside the board, how do they get transported outside the board, because...with a sealed board, you pull the perfect vacuum and the air stops moving. The air might be saturated with molecules, but it's not moving to the exterior of the board. I witnessed it tonight. I pulled a vacuum of 15" HG (7.36 psi), and the pump shut off and didn't cycle back on. It is built to cycle back on when the pressure drops to 12" Hg, but with a perfectly sealed board, that didn't happen. I'm of the opinion that it might be necessary to ad a tiny hole at the opposite end of the board from the vacuum pump hose connection to let a small amount of air into the board, to carry away the water molecule staturated air. If the hole is too big, you can't create a low enough atmospheric pressure inside the board to pull the water molecules out of the styrofoam. The tiny hole would be sealed once the board is fully dry. I'll experiment a bit in the morning with it.

Note: Inches of Mercury and PSI have been corrected to the proper values.


Last edited by thombiz on Mon Oct 28, 2013 8:24 pm; edited 3 times in total
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swchandler



Joined: 08 Nov 1993
Posts: 5818

PostPosted: Sun Oct 27, 2013 4:12 am    Post subject: Reply with quote

Bob,

Some years ago I was at Eva's shop, and she showed me a board that she was "drying out". She had the pump hooked up to the vent plug area of the board, and she also drilled a hole in the nose of the board to allow outside air into the board. As I recollect, the board was also located in a contained heated environment to help facilitate the evacuation process. From what I understand, she would run the set-up for an extended period of time, maybe as long as a week. The key is using a light vacuum pull so that the structural shell of the board wasn't under any real stress during the process.

Whether this process would extract 100% of the water in the board is always questionable, but I thinking that it would improve the situation greatly.
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jsampiero



Joined: 20 Jun 2006
Posts: 676

PostPosted: Sun Oct 27, 2013 6:48 am    Post subject: Reply with quote

Cool post. Did you pre-weigh? Curious to see the final result.
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Sailboarder



Joined: 10 Apr 2011
Posts: 439

PostPosted: Sun Oct 27, 2013 6:57 am    Post subject: Reply with quote

I asked an experienced lab technician about the use of vaccuum. He said that to get rid of water, he often had to fight ice formation. He has no experience with boards, but with lab equipment. If a lot of evaporation is going on, ice particules will form locally and will slow down water removal.

I unfortunately never tried because I was unable to buy or rent a pump that could run 24/7 at a decent price. But I was planning to heat the board. The extra hole is not required for sure since vapor will get by itself to the pump, but it may be faster, I don't know.
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jingebritsen



Joined: 21 Aug 2002
Posts: 2420

PostPosted: Sun Oct 27, 2013 6:57 am    Post subject: Reply with quote

i had heard somewhere that if one opens the vent screw of a leaking board, the water will migrate toward the vent. other than using a centrifuge, dunno what the solution should be, other than open the leaking area up lots, and store it in a hot and dry place for months....
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Sailboarder



Joined: 10 Apr 2011
Posts: 439

PostPosted: Sun Oct 27, 2013 7:59 am    Post subject: Reply with quote

My personal project was to remove water from a big 80's board with close to 20 pounds of water in it. Water seeped in for years from two small cracks. Stored outside in winter, the board would bulge in these areas from the ice forming inside. I was hoping to remove 15 pounds of it.

I enlarged the cracks to help drying, even drilled the foam to facilitate evaporation. I baked it in the sun, upside down or not. I let it inside open with a fan in winter (winter is quite dry here). I got less than a pound out of it. The foam was now dry to the touch, but water was still found inside.

In the end, I replaced the foam close to the cracks, and glassed it. The board is not much lighter but it didn't crack last winter. It spent all summer in the water, moored at the cottage. I wonder if it will survive winter again!

I read somewhere that vaccuum is the only way to dry a board. I now believe it's true since the other methods didn't give results in such an easy case.
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xander.arch



Joined: 23 Apr 2009
Posts: 189

PostPosted: Sun Oct 27, 2013 9:53 am    Post subject: Reply with quote

Nice shop / loft. Looks like you've got a bunch of cloth for windsurfing sails? Are you a sailmaker?
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thombiz



Joined: 25 Jun 2007
Posts: 556
Location: Corpus Christi

PostPosted: Sun Oct 27, 2013 11:35 am    Post subject: Reply with quote

Hi xander, I'm the local sail repair guy. I was pleased to see the interest in this topic this morning and it inspired me to get busy and be more "scientific" in my approach.
First, I should explain the board and some of it's design features. I built this board about 5 years ago. I wanted a tough, turny board to try some old school freestyle on. To make it tough, I used 1.5 lb. density styrofoam instead of the 1.0 lb density foam normally used. The reasoning was...the 1.5 density has a much higher compressive strength than the 1.0 lb density. I'm sure my memory is off a bit, but I recall that 1.0 lb. density styrofoam has a 12 psi compressive strength, while 1.5 lb. density has something like 25 psi compressive strength.
To help reduce the extra weigh from the higher density foam I decided to core the styrofoam blank, so I cut the board blank in half, separating the top from the bottom and used a router bit to make "coring" chanels in each half something like this:

Then I glued the two halves back together and completed the build. This coring tubes allow some air movement within the blank, and it should make this vacuum pump removal of water a snap.

This morning I weighed the board on my scale which is accurate to 1/10th of an ounce, it weighed 23 lbs and 13.6 oz. so that is now our base point weight.


Here is a pic of the brass connector off the vacuum pump which just happens to screw into the top of a Chinook vent plug.


I slipped the black plastic condom over the board and drilled two small holes in the nose of the board to let in air. You can control how much air enters the board by putting a piece of tape partially over the holes, varying how much of the hole is covered to regulate the amount of air passing into the holes.


I let the bag get good and hot, then I turned on the vacuum pump. I'm not worried about ice forming inside the board from the vacuum, but the heat from the plastic bag may help evaporate the water inside the board. Right now, I've balanced the inlet flow with the outlet flow to achieve a constant 10" Hg suction of air thru the board.



I thank you all for your contribution. Seems like I've gleaned some very valuable contributions from each of you. Surely if this succeeds, you will share in the accomplishment.

To keep my posts on this topic near the front of the topic so they don't get lost buried near the back, I've decided to post updates here.

PLEASE CHECK HERE FOR UPDATES:
1. After about 1 hour, I checked the clear hose and there is some water inside the hose, which you can see as it bubbles as the vacuum air passes thru it.
2. If you are interested in building your own vacuum pump as I did, here is where I got the plan and purchased some of the items. My pump is featured in the nineth pump down on the right side of the page. http://www.joewoodworker.com/veneering/welcome.htm
3. I check the hose at about 2 hrs for water buildup. There was some water but not more than an ounce. It appears the water molecules are not condencing in the hose, but are passing thru the hose and out the pump. I'll know for sure next time I weigh the board.
4. At 2 hours, inside the board there is a "gurgling" sound near the vent outlet.
5. If I were going to do this often, it would make sense to get a medical speciman jar like those used with medical vacuum pumps to collect the moisture, like this one on Ebay.
6. Sunday: Ran the vacuum pump for 9 hours and re-weighed the board...23lb. 9.8 oz. So in 9 hours I was only able to extract 3.8 oz. of water. I'll do it again tomorrow.
7. Monday: Was busy part of the day, so only ran the vacuum pump 6 hours today. Only extracted 0.6 oz. or water. This must be the diminishing returns Eva warned of.
8. Tuesday: ran the vacuum pump about 7 hours today and extracted about 0.6 oz. again. There was no gurgling noise.
9. Wednesday and Thursday, no vacuum pumping due to rain in forcast.
10 Friday 9 hrs. clear sunny day 23 lb. 7.4 oz. at end of day for 1.2 oz. extracted.
11. Saturday 7 hrs. clear sunny and low humidity 23 lbs 6.2 oz. for 1.2 oz. extracted. A cold front came thru with much lower humidity than normal.
12. Sunday 7 hours mostly sunny 45% humidity 23 lbs 5.8 oz. for 0.4 oz.

Sunday's extraction of only .4 oz was pretty small given the humidity was low by our standards. I think I'll stop here.


Using a vacuum pump to get water out of a board definitely works.



Last edited by thombiz on Sun Nov 03, 2013 6:02 pm; edited 11 times in total
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kmf



Joined: 02 Apr 2001
Posts: 326

PostPosted: Sun Oct 27, 2013 1:30 pm    Post subject: Reply with quote

I checked the board lady's web site and she suggested that the outlet to the pump should be the highest point of the board when doing this. This is because hot moisture laden air is lighter than what is in the board. She also suggests heating the board to no more than 110 degrees to lessen the risk of heat damage adding to your woes.....

http://www.boardlady.com/waterextraction.htm

KMF
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