bobwil wrote: Could one fin get it done?
I've found that one weedfin covers a lot more wind range than one standard fin. I've got a 12" weed fin that I bought at Windsurfing Hatteras (I forget the manufacture...it's blue!) which I've used from 5.5 to 7.0 with satisfactory results.
The thing is, I love fins, own about 14 and am happy to buy more, but despite my best efforts to "need" another weed fin, one has been serving me just fine.
I agree with those who suggest making the purchase in Hatteras. The shops know what's working with what.