Candidates for the loss column might include Lake Champlain, in which American warships defeated a British flotilla off Plattsburgh, NY in 1814, blocking a British invasion of New York State, and the Dodacanese Islands in 1943, in which a counterattack by German land, air and naval units ousted the British from the Aegean Sea, sinking six destroyers and two submarines in the process.
Valcour Island might also merit the loss column. Although the British thoroughly defeated a ragtag American fleet in Lake Champlain in 1776, the delay caused by having to fight the battle forced the British to abandon plans to invade New York.
The trouble with citing Valcour Island as an American victory is the name of the colonial commander, General Benedict Arnold.