restoring a fiberglass hull below the waterline

[m. brennan]

I have removed Bottom paint for the first time on a 1982 hull. which was approx. 1/8 thick. after removing the bottom paint I sanded the hull to raw fiberglass removing the gell coat if it survived under the paint. what should be the next step.

 

[Siggi]

How long did you sand ?

I find it hard to believe you sanded off the entire gel coat, how big is this boat ? I would clean it with acetone and apply 6 or more coats of west system epoxy as a barrier coat. Make sure you work the coats wet in wet. The bottom will look like new.good luck

 

[John Dawson]

And then...

after you've done this, you read the next page and the instructions usually say "but first, determine the moisture content of the hull." What is the moisture content? Was there evidence of blisters at any stage? How long was the boat in the water? Have you used a moisture meter or patch test or tap test or had it surveyed? The next step should be determining if and how much the hull needs to be dried out before sealing it with barriers. At one extreme is the new expensive hotvac process. At the other is just going ahead and applying barrier coats. In between is the usual process described in books by Don Casey and others of letting the hull sit for months and using a patch to evaluate the dryness.

 

[Rock Smith]

Dry, dry, and dry - then seal

I was impressed wiht your ambitious sand job including the gel coat! On a dry hull, you would have to apply some type of barrier to encase the laminate. Easily accomplished with Epoxy or vinyl ester barrier coat. Then apply anitfoulant.Your first hurdle now is to ensure moisture content is low (below 7%) before doing any sealing. Without dry laminate, you will encase moisture which is undesirable. Several approaches to dry exist: One favorite is seal the boat and place a humidifier in bilge for a few weeks. Check moisture content regularly to track reduced readings. Be aware any moisture meter is subjective, readings is not hard science but an indicator of direction of moisture content in laminate. You wnat descending numbers. During the above process, choose several spots on the hull and take readings at each site marking with paint pen, to track what's happening.Good luck.

 

[Tim Donley]

Steam clean......

During the drying process steam cleaning every few weeks will heat up surface promoting drying and remove the salts , minerals ,& any volital solvents embeded in the laminate.I had read a story of where the boat was reading wet with all of the prescribed methods and should have been long dry. It seems the salts and other contamination was giving a false read to the moisture meter (conductivity). When it was steam cleaned a few times it was reading well within the acceptable levels. After reading this , a friend was having a similar situation so he pressure washed (hot water) and achieved similar results. Give it try, you have nothing to lose and a lot to gain. Its not always moisture that you are reading but contamination that is not only conductive but also absorbing moisture from the boat and air.

 

[MrBill]

after dry, west expoy, then barrier additive

I did the same thing. after its dry, you will apply 4-8 coats of west epoxy.I used the slow hardner, very thin coat first, then re-applied 2-8 coats when last was tacky. (you can go a little heaver on 2nd coats as the 1st will help hold the weight. I then let it dry over night, light sanded, and added barrier coat additive (per west system instructions), and re-applied. (you can also add graphite, or copper, i didn't)then final sand, and bottom paint. If the boat is big do sections/