For our immediate surf area, the best buoy for swell read ins is the block island buoy. It will show wave height and swell height. It will also show duration or distance between swell. This is calculated by the buoy giving an average of its up and down movements over a 20 minute period. The longer the interval (seconds) the further the waves traveled and the better chance they have to become organized as swell. A reading of 6′ @ 6 seconds is just chop. Not pleasant in a small boat. But 2 ‘ at 14 seconds may be nearly head high at the beach and quite fine in a boat. When a swell hits a beach, it nearly doubles in size. Of course with long period swells (lets say 10 seconds or greater) Some variation of offshore wind would be ideal. That way the swell can arrive without “chop” on it. Creating a smooth wave face for surfers. Under water contour will also effect the shape and quality of a swell. A deep to shallow spot such as an outer reef or rock outcropping will create a possible fast breaking, steep, and hollow wave. Some times sand bars near deep water will do this also. Point breaks where a piece of land jets out into the deep usually create a ruler edge peeling wave that is easier to manage and with a channel or deep paddle zone near by.