Caring for Encapsulated Ballast Keels

Posted by By Darrell Nicholson at 11:00AM - Comments: (9)

Old iron centerboards require the same treatment as bolt-on, iron-ballast keels.


If your boat has an encapsulated iron keel, don't get lulled into believing that you are completely free of keel worries. Although you are generally better off than sailors with exposed iron keels, you still have to carry out routine maintenance and inspection, and be aware of the warning signs of water intrusion, which could lead to bigger problems.

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. And more recently we've looked at the spate of keel-ectomies among older cruising boats boats with high-aspect-ratio fin keel designs.

A mystery rust streak near the keel we noticed during a recent haulout of Lost Boys, an Endeavour 42 that has served has a platform for a number of Practical Sailor tests, 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.

Skin-deep Beauty

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 epoxy resin thickened with microspheres or micro-balloons. In January 2016 we compared two-part paste fairing compounds from Jamestown Distributors, West Systems, Interlux, Systems 3, and MAS, and in the August 2017 issue we test several mix-it-yourself options using micro-balloons and epoxy resins. You can form and tape waxed paper (backed with cardboard or thin veneer if needed) 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.

Comments (9)

what happens to a lead ballasted keel when exposed to salt water?

Posted by: peter woodsworth | September 28, 2019 11:49 AM    Report this comment

It would be useful for PS list which manufacturers use iron encapsulated in their keel.
I am surprised to learn that many old sailboats have iron instead of lead as encapsulated ballast.
Is this issue common or just a slow news day?

Posted by: Ejae | September 26, 2019 3:31 PM    Report this comment

While there is talk about troubled encapsulated keels I have never seen any photos of boats showing that this type of damage has occurred. More photos please.

~ ~ _/) ~ ~ MJH

Posted by: MJH | September 26, 2019 12:12 PM    Report this comment

I have ecpsulated cast iron in my keel. I also have a centerboard slot in the keel. The iron is either side of the centerboard slot. The boat started leaking two years ago. (1968 Sailmaster 22- S&S design). Tried to glass/epoxy a solution inside bilge and under floor boards. To no avail. I believe that the cast iron started to rust on one side and expanded. Created some seepage which allowed ice expansion to crack the centerboard slot where it cannot be accessed. Took a large section on the outside of the fiberglass skin out of the keel and found rusted and corroded cast iron. Prevents access to the centerboard trunk from the outside. Anyone have a solution?

Posted by: Jim Whitin | July 2, 2017 8:55 PM    Report this comment

Another aspect of encapsulated iron ballast is the form of the ballast, i.e. one piece or multiple pieces. Should water ingress the area the iron begins to rust and expand eventually creating a bulge in the keel. This will surely occur with a one piece ballast. My thinking is that an iron ballast made up of numerous irregular pieces will have numerous small voids throughout the area and possibly handle any expansion better when it occurs taking the avenue of least resistance.

~ ~ _/) ~ ~ MJH

Posted by: MJH | June 29, 2017 11:06 AM    Report this comment

Some boats have concrete encapsualted ballast. Caliber & Aloha are 2 I know of. No matter what the encapsulated ballast, if water has intruded through the bilge or elsewhere you may get bulges in the keel when the boat is hauled in a Northern climate when the water freezes and expands. This can cause substantial damage.

Posted by: kenneth j | April 17, 2013 2:40 PM    Report this comment


You are correct. There is iron in the keel. Construction details from review of the Island Packet Estero indicates lead as well, probably what fogged our aging mind:

Hull: The Island Packet Estero is solid, hand-laminated with heavy-knitted fiberglass. The leading edge of the keel, which has six layers of fiberglass, is more than an inch thick. Ballast (7,500 pounds of lead and iron) is laid in cavities in the keel and another thick layer of fiberglass is applied on top, in effect creating a double hull along the keel. The hull is reinforced with a structural grid. This is joined to a molded liner, and then bulkheads are taped into place. Vinylester gelcoat is used in the skincoat throughout the hull, polyester resin completes the laminate. Both are proprietary blends that have held up well. A 10-year warranty covers osmotic blistering.

Posted by: Darrell | April 17, 2013 1:32 PM    Report this comment

I had a 1998 Island Packet 45 for 10 years. It was an extremely well made boat, and I was there for many aspects of its building in Largo, FL.

You state that the encapsulated keel is lead, but in fact it was ingots of iron encased in epoxy. It seemed like hundreds of them were placed in the keel and then more epoxy was used to fill the voids. Any impact might expose one or a few of the iron ingots to the elements, but not all. I had this discussion with the factory (lead vs iron) at the time and was assured it was a solid design.

Still, its not lead as your article says. Maybe they have changed their processes, but the bulk of IPs out there are older boats and this would be how they were built.

My current boat (a Hylas 49) uses lead in the enclosed keel as built from Queen Long Marine in Taiwan.

Rick Fricchione
S/V Black Diamond
Hylas 49-057
Portsmouth, RI

Posted by: RICK F | April 17, 2013 11:36 AM    Report this comment

The Pearson 323 is another example of an encapsulated keel. Production of these stopped in 1982 and you see some that are "weeping" on the hard and the stains appear to be brownish red as if the ballast is iron. Your point is well taken that most boaters with encapsulated keels are not as diligent as they should be because they don't have to worry about the keel/hull joint or rusted keel bolts.

Posted by: Dennis R | April 17, 2013 11:32 AM    Report this comment

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