Drying a hull for bottom job

[Gary]

Hi,I have a mirage 27 that spent a long time sitting in fresh water, and had about 6 large 2-6 inch diameter blisters in the outer laminate (CSM). The gelcoat itself has no blisters. The boat has been out of the water for 1.5 yrs. now. I have grounded out the blisters and removed the bottom paint. Originally, the moisture meter was off scale, now ranges in from 12 to 20%. Above the waterline, the reading is 8%. I have recently wrapped the bottom in plastic and have placed a dehumidifier to help dry the boat. Any ideas on how long and how low should the readings be before I repair the bottom and add an epoxy barrier? I want to get the boat in the water spring of 05. What is the downside of a barrier job before all the moisture is out? Can moisture leave the hull from the inside if the barrier coat is placed "prematurely"?Thanks

 

[Bruce Niederer]

Drying the hull

It's a good practice to wash the hull where ever you have ground down the surface. A simple hosing off will do. The reason is that the fluid that often weeps from blisters is an acidic solution of the polyester resin used to build the boat and it does not evaporate very readily. Water will remove the sticky residue and hurry the drying process. In some cases the blisters represent the symptom of more severe hydrolysis within the laminate. This can be picked up by moisture meters. Placing the dehumidifier inside the cabin is a good idea. I suggest you get a copy of our 002-650 Gelcoat Blisters: Diagnosis, Repair, and Prevention manual which contains a detailed explanation of what's going on and outlines a number of repair options. If you can't find a copy where you buy WEST SYSTEM epoxy products, contact me and I'll see you get a copy.