Refrigeration vacuum pump for drying out GRP

I also found this article which i think is also relevent

http://www.yachtsurveys.co.uk/faq_osmosis.htm

basically on the premise that its not just the water that need removing but more importantly the contaminants it reacts with within the grp.

Found some great reading here as well

http://www.passionforpaint.co.uk/Osmosis.htm

 

Hi fiberglass jack, can you give some details about your vac pump? I have a Lightning sailboat that i fear may have water in the hull so i am looking at options. I am getting a Skipper+ moisture meeter as a start of exploring my options. Thanks

 

I missed this one years ago, but WHumphreys has it figured out. The blistering process is a chemical reaction, within the laminate. The chemical changes that occur, cause the blistering, as well as environmental changes (freeze/thaw cycling). Pulling a vacuum can remove some of the moisture, though you'll need to leave it under a good suck, for quite a while to get most of it, as it's got to drag it through the laminate matrix. Simply put, pulling a vacuum can help, but isn't a guarantee. Peeling a whole hull is a huge expense and not a job recommended for anything but experienced pros. A novice can do it, but you'll be fairing your brains out for some time.

For your Lightning, consider addressing the blisters as they arise and conventionally. Grind them out, dry them out, then make standard localized 'glass repairs, as required. This will save you tons of time and materials, trust me. Will the blisters return, yep, some will and new ones may show up, but wholesale peeling of the hull and bagging is a whole different can of worms, that needn't be opened if you can avoid it. Most blister jobs just require they be opened up and repaired, so the first go around will get the majority of them.

 

Hi there, Im thinking of using this method to dry my transom. Boatbuilder said it’s still solid, just need to dry out and seal. I saw some vacuum pump but I’m not sure if it’s the type I should be using because I know nothing about vacuum pumps. Will this work?

 

Would something like this work?

VCX- 155 / 205 VCX Series Claw Vacuum Pumps Malaysia, Selangor, Kuala Lumpur (KL), Kajang Supplier, Suppliers, Supply, Supplies | VES Industrial Services Sdn Bhd https://m.wonvac.com.my/index.php?ws=showproducts&products_id=2544589&cat=Claw-Vacuum-Pumps&subcat=VCX-Series

it’s the VCX- 155

 

You don't need a monster pump. It only needs to maintain the low pressure after the air is exhausted.
1 and 2 Cylinder Engines - Engine Mounts https://www.motor-mounts.com/motorsteunen/1-en-2-cilinder-motoren.html

 

The process works, but isn't as fast as what was hoped for in the original thread.

As mentioned, you don't need a huge pump if you can seal the bag good enough, any leaks and it's an uphill battle though.

The pump needs to be able to run continuously for extended periods of time, it isn't a two day job. There is no way to accurately gage the amount of time needed to dry out wood encased in a laminate. You may see the water at the surface be reduced quickly, but it will take time for any moisture deep in the structure to find its way out.