I just purchased a Catalina 30 MkII with Tall Rig and a Bow sprit.This is my first boat.I am confused by all the sail measurements I see.Catalina shows the following for a tall rigI= 43'E = 12'P= 37'6"J= 13'1 7/8" The Genoa is in rough shape and I need to replace it.There are lots of places selling used sails but they talk in Luff and leech measurements. I have tried to figure out what they would be but get more confused the more I research. Can someone make this easy for me?The boat has Roller furling.ThanksKen