It all depends. If you sail in SoCal or Long Island Sound
, you can't have too large a sail. In SF Bay
, a working jib
can be all you need. The boat also effects the sails needed. An IOR design with a small main and big 'J' NEEDS a 150 while a big main, small 'J' boat works fine with smaller headsails.
As others have said, assess the prevailing winds in your area, how much of a problem it's going to be to downsize. I'd reccomend changing a 150-160 genoa
when you feel the need to reef. If things get worse and you reached the furling
shape limit of the sail, it's going to be a whole lot easier to do it at 15 knots of wind than even 20 knots. You can go with a lighter fabric
for better lightwind performance that way as you'll not have the be leaving it up and furling
it in 30 knots when you should have changed it out long before.
Also, you might think about an Asymetric chutw for reaching and running in lighter conditions. You can put up a lot of square footage with an Asym and cover a lot of the sailing spectrum. With an ATM sock, it's a relatively easy sail to handle. Won't get you to weather
if there is much of a breeze, unfortunately but is surprizingly close winded when its light out.