Epoxy paint works well on properly prepared steel or iron keels. We've been using it on a steel schooner.
The iron needs to be throughly cleaned and brought to bright metal by sanding, grinding, or sand blasting. Immediately coat the keel with a Phospho or similar product to convert the iron oxide (rust) to iron phosphate. Iron phosphate is a paintable surface. Then paint the keel with an appropriate epoxy paint.
Epoxy paint can have different formulations to meet different requirements, I'm not certain if epoxy pool paint is a good match for for a sailboat keel. While a pool bottom and a keel are both submerged, the substrates are different. The characteristics that make a good paint for a concrete surface may be not work as well on an iron keel moving along at 6-7 knots. There would also be temperature cycling, a pool, especially an indoor heated pool will not have the same expansion and contraction cycles that an iron keel will experience. My choice would be a marine epoxy barrier coat. Both Pettit and Interlux make epoxy barrier paints and should be available in Canada.
