The term 'to the rear, at sea' can be expressed in three different ways. The first is 'ASTERN', which is a nautical term meaning 'toward or at the stern (rear) of a ship'. The second is 'ABAFT', which is another nautical term meaning 'farther back than; behind'. The third is 'AFT', which is a shortened version of 'ABAFT' and also means 'toward or at the stern (rear) of a ship'. All three terms refer to the same concept: being at the rear of a ship while at sea.