Build a Vacuum System to Dry Boards

[PonoBill]

Beasho's holes are not in structural areas at all. I still repair anything that I think needs structural help, but I'm not so sure that even a careful repair is an improvement over a ding. You expand the damage by sanding, which cuts glass fibers in a much larger area, and glue on a patch, which is discontinuous and hardens at a different rate, probably is not the same glass schedule and is probably a different epoxy formulation. I certainly see the value from a cosmetic standpoint, and I'm as awed as anyone by expert and careful repairs (mine never are), but I'm not so certain about the engineering properties--either strength or as a stress riser. I agree that if you're going to repair a board then you need to do it right, solarez or slapping on a wad of glass over the paint on an unfaired ding doesn't work at all, but in my experience, two layers of aluminum tape works very well even as a long-term repair, especially if you burnish the first layer with a piece of rounded plastic to get full adhesion. But yes, my venerable and fragile Maui downwind board looks like hell, but hasn't gained weight (it was always heavy) or leaked any water (it's hollow, I'd know) despite dozens of through the skin leakers that I patched as many as four years ago. And it remains in one piece, despite my 230 pounds floundering all over it in challenging conditions.

[Bean]

I'm not so sure that even a careful repair is an improvement over a ding.

👍

[Beasho]

Final Report on the 6' 6" - Weight 19.2 lbs AFTER REPAIR work.

[Bean]

Nice job Beasho!

[Beasho]

These were 2 of the primary repairs to the nose. 

I sanded down all the abuse and covered with a layer of Epoxy and Microballoons - Let Dry

It was pretty much water-proof at that point.  Then I added:

• 2 Layers of 6 oz Carbon - Wetted on a table
• 1 top layer of 2 oz Fiberglass - Wetted on Table
• Covered up with clear packaged tape under tension

Board is now water-tight and I am adding some Rail Saver to these nose sections for added future ding insulation.

[Beasho]

The 15/64" air holes that I drilled were the easiest to cover back up.

I took a 1/4" dowel and inserted it until it stopped.  Cut it at length ~ 1/2".  At this point it weighed almost nothing.

I gorilla glued the dowel tight into the hole recessed maybe 1/32".  Let dry.

In this example on the tail I took a small bit of epoxy mixed it with a touch of red die and then covered the hole.

Took a strip of Packing tape and covered then let dry.

The coloration is more obvious in this photo than it appears to the naked eye.  It's nearly imperceptible. 

This is a good thing because I am more inclined to drill holes and dry boards now.

[Beasho]

The madness continues:  I am drying another board my 9' 2" PSH Hull Ripper. 

It started at 23.4 lbs without fins.  I got it down to 23.2 lbs overnight with vacuum pump and heater.

What I have realized is that HEAT is as important as Air flow and Vacuum.

Heat can be CHEAP in the form of sunlight but given our short Northern California days, and plenty of cloudy skies, I am now improvising with artificial stimulants. 

My latest theory is to gently cook the boards at 120 to 150 degrees.  I haven't figured out the best temperature but I DON'T want to compromise the boards lamination or underlying EPS structure.  I read that EPS will breakdown at 212 degrees.  Oddly similar to water.

To get the WATER out of the board I also need to push the limits of that temperature.  Typically putting a board in the sunlight can be damaging.  However when under a vacuum there is LITTLE chance of delamination because the board is under NEGATIVE pressure.  I am also realizing that the boards MOST at risk of delamination in the sun are water saturated.  The water expands as it vaporizes even more than the hot air . . . .

Any ideas on how to safely and economically cook the boards while under vacuum?  This thing claims to have temperature control and is ~ $25 on Amazon. 

https://www.amazon.com/dp/B07456SPMF/?coliid=IJVWF5E7QQQTT&colid=1UI7W46HW56MH&psc=0&ref_=lv_ov_lig_dp_it

[mrbig]

Small room. Electric heat. Parabolic is good. 100 degrees. That and the aqarium pump setup I described got all of the water out of my RNB. Took three days once I left it alone.

I suspect a much older and more waterlogged board would take longer.

As always your YMMV!

[Bean]

Remember the greater the vacuum, the lower the boiling temp

[TallDude]

I glassed a smaller board and did my post cures in a taped together box made of foil back 1/2" sheets of rigid insulation foam. Then stuck one a electric radiant heater I bought at a thrift store for $3.00 ea on the floor under the board inside of it. I stuck a cooking thermometer through the foam on the lid, then adjusted the heater to get it right.  You don't want to get the foam board to much over 110 degrees. The foam first expands them a little more heat and it collapses. The board looks like it caved in. My shop is has a 10' ceiling and is about 12' x 25'. It' insulated drywalled. Two of those electric radiant heaters will get my whole shop to about 95 deg. That's hot enough for a post cure cook off when I'm glassing a board. A fully cured hard epoxy is so much nicer to sand and finish. If you don't cure it with heat, it always feels kind of soft / rubbery.

[J-Bird]

The madness continues:  I am drying another board my 9' 2" PSH Hull Ripper. 

It started at 23.4 lbs without fins.  I got it down to 23.2 lbs overnight with vacuum pump and heater.

So Beasho, how do you know the .2 lbs you lost didn't just come from the deckpad drying out?  You need to analyze data and not just take it.  Big difference.

[Beasho]

So Beasho, how do you know the .2 lbs you lost didn't just come from the deckpad drying out?  You need to analyze data and not just take it.  Big difference.

Let me guess you are not an engineer and feel threatened by data. 

The board had not been used for more than 2 months - dry as a bone.

Any more data insights that would be helpful we'll be happy to sit by your knee and listen. 

[Beasho]

Remember the greater the vacuum, the lower the boiling temp

This is true but pretty extreme.  Our vacuums are drawing ~ 24 inHG (Negative). 

The attached shows the boiling point of water vs. pressure.  It's in Centigrade and I added some conversions.

At 20 inHG the true pressure is close to 9 inHG in the chart meaning the boiling point is still 150 F.  Pretty toasty.

The reality is that to convert water to gas takes an EXTREMELY high amount of energy.  540 calories per gram to vaporize vs. just 1 calorie to raise a gram of water 1 degree C from 25C to 26C.  The vacuum could be thought of as a tradeoff using the energy to CREATE the vacuum vs. vaporizing the water with heat. 

If we just cook the water then it sits there.  So the constantly running vacuum helps to draw out the moisture which is also necessary. 

You have probably been using this vacuum trick for a long time, therefore applying on fresher dings.  This board's weight is a combination of historic repairs, that you have pointed out MAY NOT ADD THAT MUCH weight, and water weight gain.   

[eastbound]

no meds pls beasho, i am enjoying the madness--and, if anything, you are dogged! youre like a board anorexic!

i like the dowel trick--think it's as good as a regular old gorilla glue fill, with a couple layers of glass/epoxy?

clearly the dowel trick is quick and easy--seems it should hold up--but if it doesnt, just drain and dry again!

[Beasho]

no meds pls beasho, i am enjoying the madness--and, if anything, you are dogged! youre like a board anorexic!

Funny but TRUE.  And I'm not even sure I want to ride that SUP anymore given my FOIL addiction.

My vacuum pump has been running almost constantly since I built it in the beginning of December.  My daughter, who keeps here rabbits in the garage, threatens every night to "turn off the pump because it disturbs the bunnies."