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Old 01-11-2020, 11:04 AM   #3
SoWhat
Guru
 
City: Boston
Vessel Name: Adelante
Vessel Model: IG 30
Join Date: Nov 2016
Posts: 1,609
Identical problem with my 85 IG. Blistering and IG's are synonymous it seems.

Barrier coat must be put over a solid surface. I started with hp power washer to take the top of the 1000's of BB bubbles. I then roughed the surface with 60G RO sander. Poked around with a pointed blade for days to remove what the washer missed. If I could see mat, I dremeled and sanded as needed. Then it's a simple (but time consuming) project of fill/fair/sand/coat/paint.

The faux planked hull was a real pain. I followed the cracks with a dremel until I reached solid bonded material. Then filled and faired. I used West with microballons. (not UV or waterproof so several primer coats advised) I put some tongue depressors to the belt sander and formed them to fit the groove. Made applying filler easier. Filler should be peanut butter consistency. (When you pull mixer out, the peaks of the filler should not fall over)

The key to success was sanding the edge of a piece of 3/8 plywood to the shape of the groove. I could then wrap a piece of sandpaper around the plywood and it was a perfect fit. It was then easy to blend the repair into the existing groove.

Note that the blisters are cosmetic. The boat isn't going to sink. IG had poor quality control. Many theories as to cause. Poor mix ratio, high humidity, cheap chemicals, shoddy workmanship, nothing definitive. I installed a through hull and the hull is thick and solid. I have no concerns about seaworthiness.

(I can post pics if needed)
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