Horseshoes can be used in other ways besides placing above doorways. Sailors have nailed horseshoes to there mast to help there ship avoid storms. One way to prevent nightmares is to place a horseshoe wrapped in red flannel above your bed. There are some people who believe that in order for the horseshoe to bring luck, it must be found as apposed to being purchased new. Most horseshoes contain seven nail holes, and seven is considered to be the luckiest number. Even horseshoe nails are sometimes used as lucky charms and amulets.