I don't know for sure what material Catalina used for the keel bolt nuts but if my years of experience with various stainless alloys in tube fittings and nuts used in hydraulics is any indication, they probably specified 316 stainless. That is what I would have used if it were my choice. The nuts should be passivated (especially for saltwater sailors) as well. To avoid the galling that is common when you have stainless on stainless, we used Parker Molylube (a molybdenum disulfide grease) on the threads. Never Seize or C5A compound would also work well but they are designed more for applications where high heat is a concern. Andy Dalzell C-27 # 6298, Tardis Sandusky Bay
