I presume you do not want the obvious answer...races between boats...so perhaps you refer to Cockney rhyming slang. In that lingo, a 'boat' is a 'face', on the basis that 'face' rhymes with 'race'. As is usual with Cockney sland, the rhyming element is dropped, so 'boats' are 'faces'. My apologies if neither of the above is what you are looking for.