Flying Sails
A gennaker or asymetrical would be my first choice for a second sail after the standard jib because it's easy to set and take down, no pole required, gear (sheets) is cheaper than a symetrical spinaker, and it provides a great increase in sail area, if the rating penalty wasn't a consideration.Once you go over 150 (or 153 in some places) percent, you get a flying sails penalty. If the courses are short and the wind angle is typically good, then the flying sail could be a good competitive sail choice too. For longer courses a standard spinnaker, depending on wind angle, becomes a better choice.Particularly for flying sails, try to get a polar diagram that shows what the sail is designed for. Look at the link below to see how spinnakers can be optomized for various wind speeds and apparent wind angles. If you only wanted to buy one sail it pays to know the course and the likely conditions.There's a lot of factors to consider. This is where having lots of money helps cuz you can buy several sails!