I've just purchased a 1975 Catalina 30TRBS, #35. Upon inspecting the main sail I noticed that the sail can be trimmed in two ways. If the leech line is slacked, the boom will drop about 1.5 feet on the aft end increasing the sail area. If the leech line is tightened the boom is horizontal and the sail shape is more traditional. In both examples the sail is fully raised. I have never seen this cut of mainsail before and was hoping that someone could shed some light on the pros and cons or best use. According to Catalina, this hull was factory racing boat in 1975/76.