SV Pilgrim - 1979 Morgan 382 - Homeport: Beaufort, NC

Tuesday, April 29, 2014

Repairs To Hull Damage and Blisters

Our pre-purchase survey noted no hull damage or blisters, but of course that would be too good to be true.  We have discovered two areas of damage and 25 blisters.

Via casual inspections of the hull since Pilgrim’s arrival in Beaufort, I’ve notice a few areas that appeared as short cracks in the bottom paint.  Dis-coloration on the bottom paint around the cracks was indicative of moisture. 
Small cracks with discoloration due to moisture marked trouble on Pilgrim's hull.
Using an awl and a utility knife I picked open a couple of the cracks…
Opening the cracks with a knife revealed dry, brittle chopped strand mat (CSM)
None of them burst or squirted a stream of fluid as I have encountered with blisters on other vessels.  Rather the mat revealed appeared dry and brittle.  I suspect these are areas did not receive enough epoxy to wet out the mat in the original construction or they are poorly executed attempts at blister repairs by a previous owner.

To date I have discovered and ground out 25 such “blisters”.  In nearly every one, the compromised material was limited to the outer layers of chopped strand mat (CSM). I found no water intrusion into the woven roven cloth layers of the hull.  In the most severe cases water moved laterally between the CSM and Woven layers creating areas of delamination.
Starboard side aft of keel - larger area of delamination on left and grapefruit sized area on right.
In the image above the area to the left represents an area of delamination.  The smaller, grapefruit sized, area on the right is representative of the typical blister without delamination.

The greatest concentration of blisters is located on the starboard side under and forward of the head.
Portside forward of keel 
Up and right in the image above is a large area ground out due to hull damage.  This site is located under the head pan just forward of the counter top . The head sink drain thru-hull can be seen just below the damaged area.  I believe this damage is caused by the weight of the head pan resting on a narrow section of the interior of the hull.
Damaged hull directly below wall supporting head counter top.
In the image above, white, discolored fiberglass indicative of stress damage is present directly under and in line with the interior wall below the head counter top.   I believe additional tabbing added by the Morgan repair team and later by myself have remedied the cause of the stress.
Portside directly below the cockpit we found a poorly executed hull repair. 
The largest area of delamination was under a poorly completed hull repair on the portside below the cockpit.  I believe the crack is from improperly loading a jack stand.
The dark brown areas are sites where water is weeping out from under the CSM layer of the hull layup.  Pilgrim has been on the hard for six months 
The previous repair consisted of some polyester resin troweled into a “U” shaped notch.  This inadequate repair allowed water to seep into the surrounding fiberglass.  As with other areas on the hull once the water found its way through the chopped strand mat (CSM) it migrated latterly between the CSM and the woven roven cloth.
Port aft hull with large area of delamination and raw water thru hull (below jackstand) ground out.
Ultimately, to remove all the delaminated material required grinding out an “L” shaped area 32” X 32”.

After nearly ten days of exposure to dry weather and no signs of additional moisture from the hull, we have begun filling the damaged areas.
Small area on starboard side filled with two layers of 1708 cloth
 Using a marker, I numbered the sites on the hull that would require 1708 cloth patches.   Once the patches were cut we placed them in numbered ziplock bags to keep things organized.  The sites were numbered 1 – 32.  If a site required multiple layers then the patches were labled A,B,C, etc . The blistered areas required one to three layers of cloth.  The two damaged areas required four layers of cloth.  Filling the old thru-hulls required eight or more layers of cloth
We worked as a team to apply the new fiberglass cloth.   Anne mixed epoxy and wet out cloth.  I applied the cloth to the hull.   We filled some of the small areas and old thru-hull holes last week (See Previous Post: Replacing Thru-Hull Fittings & Seacocks – Part 1).
Large area on port side filled with up to 5 layers of 1708 cloth

Confident from last week’s success we tackled the large 32” X 32” area on Monday afternoon.  The damage required up to four layers and around 20 square feet of 1708 cloth.

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