The general rule of thumb for your boat is 1 inch of flag length for every foot of boat length. A 30 foot boat should have a 20 x 30 inch flag.

Flags - Product list

Annin Nyl-Glo American Flags Johnson Tuna Tower Halyard Kit Taylor Made Aluminum Flag Poles Taylor Made U.S.P.S. Ensign Price: $ 16.79 Price: $ 62.99 Price: $ 19.94 Price: $ 15.74 Taylor Made US Yacht Ensigns Taylor Made USCG Auxiliary Flag Price: $ 15.74 Price: $ 8.39