O'DAY Flying Saucer
Sounde like you have an O'DAY Flying Saucer. I don't think that too many were built, but this was a sloop-rigged, board-boat. On the O'Day Owners Unofficial Website there is a link to a 1968 O'Day sales brochure with pictures of this boat. the Flying Saucer is 15' loa, 5' 2" beam, pretty close to your dimensions. There wa an O'Day 15 built during the early 1970's, but it was 14'11" long, 5' 10" wide, and much deeper than 6". There was also an O'Day 15 built in the 1980's, but it was 14' 7" long, and 5' 11" wide, and again..much more than 6" deep. I've listed the address for the O'Day Owners Unofficial website, take a look!