According to the U.S. Naval Historical Center in Washington, there is no official motto for the U.S. Navy. However, Non Sibi Sed Patriae is often used and cited as the official motto even though it is not.
There are many other unofficial mottos associated with the Navy and Naval units as well.
U.S. Navy units
"Not self, but country" is the unofficial motto of the United States Navy.
The motto of Indonesian Navy is 'Victorious on the Sea'.
The motto of Royal Canadian Navy is 'Ready Aye Ready'.
Navy Children School's motto is 'ज्ञानेन शोभते'.
The motto of Royal Navy is 'If you wish for peace, prepare for war'.
"Not self, but country" is the unofficial motto of the United States Navy.
If you are speaking about the Navy's "motto", they don't have an official motto per se, but a lot of people claim it is "Not self but country".
Indonesian Navy's motto is 'Jalesveva Jayamahe'.
Italian Navy's motto is 'Country and Honour'.
Colombian Navy's motto is 'further beyond'.
The motto of Indonesian Navy is 'Victorious on the Sea'.
Royal Malaysian Navy's motto is ''.
Chilean Navy's motto is 'Vencer o Morir'.
The motto of Royal Canadian Navy is 'Ready Aye Ready'.
Hellenic Navy's motto is 'Great is the country that controls the sea'.
The motto of Australian Navy Cadets is 'Integrity and Endeavour'.
Navy Children School's motto is 'ज्ञानेन शोभते'.