Tampa N20,
Chris is out of town so i'll take a minute to respond. The N20 fleet was really born (or atleast re-organized) out of the Tuesday night racing at West River that was started by Keith and Roger. They were able to get a site for mast up storage where access to the water was relatively inexpensive and relatively easy to get to. Couple that with the fact that most of us have very busy schedules and you have a recipe for success. This is really where it started and the OD part followed as people enjoyed racing boat for boat. The Tues. night racing scene is still a run what you brung open class but the OD stuff has grown and gotten established at one of the local yacht clubs which adds more weekend events. I think the real key to growth here has been the mast up storage. The less effort it requires to go sailing, the more sailing people do.
The only downside is that it makes it harder to motivate folks to travel to events away.