human
Considering the provided database schema and associated query, produce SQL code to retrieve the answer to the query. 
###Database Schema: Position, Sail number, Yacht, State/country, Yacht type, LOA (Metres), Skipper, Corrected time d:hh:mm:ss
###Question: What is the number of the sail with an overall length of 13.68?
gpt
SELECT Sail number FROM table WHERE LOA (Metres) = 13.68