Its the insignia of a an evil curse from a one eyed withdoctor/shamin that cut the head off of a chicken and spread its blood all over the boat while dancing counter clockwise, under a full moon, ensuring all fish caught off this boat will be 1 inch under size, you'll going to have to get Mr. Krinkle and his special magic to take the hex off before putting a rod in the boat
either that or just spray some oven cleaner on it to take it off