Blister Repairs 2015 Session

Removing Pilgrim’s remaining bottom paint revealed 38 previously undiscovered blisters.  Unlike last summer’s blister & hull damage repairs (photo album – Hull Damage & Blister Repairs 2014), the blisters discovered recently are not linked to ill fitted or ill tabbed internal structures exerting focused pressure on the hull.  Nor did any of them lead to delamination or areas of cloth lacking resin. 

With the bottom paint gone, tiny seams or pock marks in the hull provided the evidence of an issue.  Following the evidence with a grinder typically lead to a void a short distance into the outer copped strand mat layer. None of the blisters were wet, but Pilgrim has been on the hard for nearly 18 months so this was not surprising.  Generally the blisters were minor… smaller than the palm of my hand and penetrating only into the outer layer of mat.

Two notable exceptions were along the port keel.  These areas were larger in size and the damage extended to the outer layer of woven cloth.

Two large blisters on port keel.

These two may be linked to hull stresses as they are located along the transition from solid lead ballast to the hollow section of the keel.

While no area of the hull was completely blister free, the starboard hull had a line of blisters extending from the cockpit area to around mid-salon area and just below the waterline.

Line of blisters along starboard hull just below the waterline.

12 of the 38 blisters were deep enough to require additional mat for repairs. I developed a fancy system for identifying which areas required glass matt and which simply needed filler.

Group of three blisters on the starboard waterline

I’ll bet the readers of this blog are savvy enough to figure out my system from a single photograph.

Our system for repairing the blisters followed the same steps we used last year.

Cutting 1708 cloth for blister repairs.

Apply one or more layers of 1708 cloth to hull

Ready for the grinder.

After curing – wash, rinse, grind with 36 grit disc, wipe down with acetone.  Then fill the area epoxy thickened with a combination of milled fibers & cabosil.  Areas not requiring fiberglass cloth (see blister in center of image above) start the repair process with an application of thickened epoxy.

Ready for sander.

After curing – wash, rinse, sand with 80 grid paper in orbital sander, wipe down with acetone.  Apply first application of epoxy thickened with fairing filler.

Ready for hand sanding.

After curing – wash, rinse, sand lightly with 80 grid paper in orbital sander, hand sand with 80 grit paper on large block, and wipe down with acetone.  Second application of epoxy thickened with fairing filler.

After curing – wash, rinse, hand sand with 80 grit paper on large block, wipe down with acetone.

Ready for barrier coat  :-)

While sanding fairing I developed a second, highly evolved system of identifying the areas completed.  Once again I’m assuming readers of this blog can deduce my system from a single photograph.

The next step, yet uncompleted, will be to overcoat the entire hull with 5 to 7 coats of barrier coat.

For more images and notes from this project check out our Bottom Job Photo Album.

No back to that lingering Ice Box Rebuild.