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July 10th

Repairing Major Keel Damage Part I

Posted by // July 10, 2013 // COMMENT (1 Comment)

Maintenance, ,

After all the work I did on my boat, I feel fairly confident in my skills as an amateur fiberglasser, but this one really put them to the test:
Port Side
Starboard Side
From underneath
Stern View
After inspecting this keel damage, I sent a very long email to the experts at West System Epoxy. A few days later, I got a two paragraph response, which said, politely, that I was on my own, that they couldn’t offer advice on this sort of damage from just a few pictures. They said, “if it was our boat” they would want “to explore much higher into the keel to look for more extensive damage.” Fortunately, it wasn’t my boat.
Between New Orleans and our current route up the Atlantic Coast I stopped in Marathon, FL for a crew change and to help my friend with this repair. The boat is a Seafarer 31, the same boat we took to the Bahamas over Christmas. The damage was from a hard, fast grounding on a reef, and we were fortunate not to have worse to contend with. Still, it took a couple days of mulling things over before we were ready to get started.
For the repair we decided on vinylester resin and bi-axial fiberglass cloth. In cost and performance vinylester is somewhere between polyester and epoxy. It is stronger and more waterproof than polyester but somewhat less so than epoxy. According to the old salt who sold it to us, it’s also easier to work with because it tacks up faster and is less slippery than epoxy. I found this to be only half true- it was a little easier to use initially and did cure faster but it was a bit less forgiving. With the slow cure of epoxy resin you can work your fiberglass cloth as it tacks up, sticking down bubbles or corners as they appear. With vinylester we had to get it right the first time or the wet glass would lose its adhesion. We got the hang of it fairly quick though and it made a fine repair for a fraction of what epoxy would have cost.
The area after cutting away damaged fiberglass
Our first step, before any work, was to cut out the damaged cloth so that we could see what we had to work with. We also drilled a few test holes to investigate the extent of the damage.
Mapping out damage and drilling test holes
View thru the holes
There was a split in the back of the keel about 14” tall and a section of damage to the bottom of the keel that extended forward for 10.” This damage on the bottom was the worst, at the back a good 1-2” of the bottom of the keel had been bashed off.
This meant we had two tasks: gluing the delaminated area back together and restoring shape and strength to the bottom. This was complicated by a hollow area extending above and slightly forward of the damage. Fortunately, there didn’t seem to be any structural damage beyond the immediate area and the keel itself was, in the whole, still sound.
The Split:
Inspecting the split
Our first, and easiest task was to repair the split in the back of the keel. When originally laid up the keel was hollow, tapering to an edge at the stern. The impact had cracked this tapered edge, leaving intact fiberglass split into two sections. We needed to rejoin them and since the fiberglass laminate was largely undamaged we started by gluing them back together. For this we used a mixture of West System epoxy and structural filler. Of the resins epoxy is the only one suitable for gluing jobs – both polyester and vinylester have little strength or adhesion when used without fiberglass but epoxy is both strong and tenacious, especially with the addition of a high-density filler.
Process:
We started by wetting out the area with unthickened epoxy. Then, we thickened our epoxy with West System 406 structural filler.

We put this goop into one of West System’s very useful caulking tubes. Then we spread the crack open with screwdrivers and a chisel and shot the thickened epoxy in.

With the crack full of epoxy we clamped it up tight and called it a day.
 This restored the shape of the keel and, in a fashion, re-laminated this cracked area. It probably didn’t restore the cracked area to its original strength but at this stage the main thing was to get the keel back to its proper shape. Later on we reinforced this section with new layers of fiberglass.
We were now ready to get down to the really nasty work!

This article was syndicated from Safe At Harbour But Meant For The Sea: DIY Sailing with Paul Calder

One Response to “Repairing Major Keel Damage Part I”

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