Posted by By Darrell Nicholson at 04:32PM - Comments: (4)
It’s getting warm enough now in most places up north that we can start thinking about getting some actual work done on the hull—thinking about. I checked the weekend in Duluth, Minn., and it still looks a bit chilly for curing epoxy. You’d think that maintenance chores wouldn’t snowball during the off season, but the freeze and thaw cycles of fall-winter-spring take their toll. One of those places where this becomes most evident is at the keel.
We’ve written a lot about keels recently, and over the years, we’ve offered tips on repairs to common problems like the C&C “smile,” when a lead keel pulls away from the keel stub, or how to deal with voids in lead keels. I’ve also written here about the effectiveness of rust converters such as Ospho when reviving an iron keel.
PS's April boat test of the Gulfstar 36 (subscribers only) got me thinking about encapsulated keels again. A lot of people like the idea of having lead (preferably) or other ballast material encapsulated. Island Packet is probably the most familiar builder today that uses an encapsulated-ballast keel. One big advantage of having an encapsulated keel is that so long as the fiberglass and waterproof coatings remain intact, they don’t require any special seasonal maintenance.
However, fiberglass is permeable, and on some older boats, water tends to find its way into the ballast. If the ballast is iron, the results can be ugly as the metal oxidizes and expands. Having a two-part epoxy barrier coat like the Interlux Interprotect system goes a long way toward preventing this kind of problem.
The chief maintenance concern with an encapsulated keel, though, is damage from a grounding. Sometimes this damage is so minor you might not even notice it, or might mistake it for chipped paint.
Fortunately, it’s not too hard to fix this sort of damage. For those who own or are thinking of buying a boat with an encapsulated keel, below I’m re-running an excerpt from the archives about spotting and repairing minor damage to encapsulated keels.
If you’re gloating because you think your encapsulated keel frees you from any worries, forget it. Encapsulated ballast frequently requires more complicated care than an external ballast keel.
The danger is damage to the fiberglass shell surrounding the keel.
Even if you haven’t run aground this year, there’s a good chance that somewhere along the way, you have acquired at least some superficial gouges in the lower part of the keel shell. These should be treated before they become problems. Even superficial damage to the gelcoat can allow water penetration into the laminate.
Treatment of superficial gouges in gelcoat or the first layers of the laminate is straightforward. First, wash the damaged area thoroughly with high-pressure fresh water. Dry the gouged area with a handheld hair dryer. Roughen the edges of the gouge with very course sandpaper—50 grit or 36 grit.
Wash the area again thoroughly with acetone. Use a small, stiff-bristle brush to clean the gouge completely. Dry again with the hair dryer, after most of the acetone has flashed off. Don’t breathe the stuff.
With the area thoroughly clean and dry, brush on a clear coat of epoxy resin, followed by resin thickened with microspheres or micro-balloons. Stick waxed paper over the epoxy patch to keep the epoxy from sagging out.
When it’s dry, sand smooth and touch up any voids or hollows with more filled epoxy.
When everything is filled, prime the patch and the surrounding area with a two-part epoxy primer. Most marine coatings manufacturers offer two-part primers, such as Interlux Interprotect 2000E or Pettit Protect 4700. Apply several coats—most makers recommend at least four. The barrier coat is important, because the gelcoat that you have sanded is now fairly porous, and is more likely to develop blisters than polished gelcoat.
Once the primer is cured, you are ready to paint. Some primers can be “hot-coated” while curing, but most manufacturers recommend allowing the epoxy to cure and sanding lightly before painting.