I was in the boatyard yesterday (I feel like I live there now) and saw a boat for sale which I thought was an O'Day 27 but could not tell exactly, except it looked "O'Day-like". When I was in the military we had Aircraft and Armoured Fighting Vehicle recognition cards, basicly flash cards to help you identify these vehicles based on the number of wheels, engines, silhouette, etc. Is there anything similar for sailboats? It would be nice to be able to identify at least some of the more common manufacturers based on simple identifying characteristics - maybe there's a business opportunity here?