and the problem of rusty keels
Recently I was asked to recoat a keel on a boat built by one of the prominent Star boat builders. The original coating was bubbling up and flaking off the keel due to rust. This is an unfortunately common problem with boats built by this company, and it has come to my attention that boats as new as only 4 years old have had to have their keels recoated, usually at a cost of between $3,000 and $5,000.
While looking into what would be the best solution to making a rust-free coating I realized that Star #3855, which I have owned since 1959 and was built by Skip Etchells in 1957, has never shown any signs of rust on the keel. I asked Jane Lawrence, who worked for Skip Etchells as a secretary at the Old Greenwich Boat Company, if she had any information about what material was used in coating the Old Greenwich Star keels. After checking around with some of the workers employed by O.G. she reported back that the keels were coated with Lithcote at the Union Tank Car facility in Norwalk, Connecticut. Skip would somehow get his keels slipped into the job order at this facility and they would be coated with whatever coating was being applied to the interior of tank cars at the time.
The principal use of Lithcote is as a tank car coating for the interior of tank cars. The description of Lithcote on the Union Tank Car website says that depending on what the tank car was destined to carry there are various colors as identification marks, this due to the fact that there were various materials used in the coatings and in the vehicle of the coating, from epoxy to phenolic. One of the colors listed is teal which is the color of the coating which is on the keel of 3855. Another is brown which from reports was the more common color of the keels when they came back to O.G. after being coated. From this I would gather that Skip was not too worried about which variety of Lithcote the keel was covered with and whatever the factory was applying to the tank cars at the time the keels arrived at the facility was good with him.
For me, it is truly amazing that after all these years the keel of 3855 shows no signs of rusting. However, applying Lithcote to the keel I had to work on obviously could not be a solution to the problem I was faced with, since the keel was already attached to the boat. I might mention that another common solution to rust prevention, at least during the 1950ís and 1960ís, was to have the keel galvanized. Again, in this case this was not an option, since the keel would have to be detached from the boat in order to get the keel galvanized.
After checking around with other boat workers who have done the same work it appeared that the best solution was to build up a barrier coat consisting of epoxy and fiberglass.
The first step was in preparing the keel. The old coating had by this time so much rust under it that it peeled off in large sheets without much resistance. The keel was then sandblasted. Aside from the obvious need to get rid of the residual rust a side benefit of sandblasting is that the surface of the keel was substantially scoured thus providing a good grip for the epoxy. Within an hour of the keel being sandblasted the first coat of epoxy was applied, this so that the humidity of the air could not get much of a chance to start the rusting process. Before the epoxy had a chance to set fairing compound made of a mixture of epoxy and microballoons was applied to fill in the blowholes and glass cloth was immediately applied over that. Another coat of epoxy was then applied to thoroughly dampen the cloth and then the whole was allowed to harden overnight. After the epoxy hardened the keel was sanded, after which the various imperfections were filled with more fairing compound, and where needed with glass cloth. Once the keel was completely faired it was wet-sanded, in part to wash off any residue amine blush left behind by the epoxy. The owner of the boat wanted to sail the boat at this point so that might have had the added benefit of further washing off any of the residue amine blush. Once the keel was thoroughly prepared gel coat was applied according to the labelís direction and then fine sanded and buffed to a good finish. Of course, any finish coating could have been applied.
It should be mentioned that gel coat is fairly porous, as are some paints. Thus there has to be some kind of impervious barrier coat used as the undercoat. Epoxy is one of those materials which seems to work well. The coating on 3855ís keel as listed in the Union Tank Car chart has as the vehicle epoxy phenolic, and this material has obviously stood the test of time.
There has been some discussion as to whether the quality of iron used in the keels by the boat builder in question is somehow contaminated, perhaps as a result of being recycled iron. It is a phenomenon noticed in cars made of predominantly recycled material that they tend to rust out sooner than those made of virgin steel. Whether this factor plays a part in rust appearing on keels so soon after the boats have been built will be tested by time, as there are now several keels which have been recoated using the epoxy and fiberglass base before a finish coating was applied. If these keels do begin to show signs of rust again then perhaps indeed the fault lays with the iron itself.
However, it has been reported that the thinking of the boat builder is that in order to have the maximum righting moment the keel should have the minimum amount of coating, thus giving the keel the highest possible density. Carrying this concept to the logical extreme, milled keels in which the keel is milled to the final shape so that no filler is necessary have become fashionable. Needless to say, the process of producing milled keels is quite costly. While this concept is correct and all very well, it would seem that applying a coat of protective material which is so thin that water penetrates it and begins to cause rust only after a short time is carrying the concept too far. Surely, having the proper amount of a protective barrier coat applied to the keel cannot increase the overall volume of the keel significantly enough to affect the righting moment.