"astern" is a correct and usable word in written English.
It is usually used as an adverb meaning 'towards the rear of a ship or aircraft'. For example, "the ship began to move astern".
The MV Perseus Leader inches into the Miraflores lock on the Panama Canal on her way from the Pacific Ocean to the Caribbean Sea and the Atlantic, 80km (50 miles) away, a tug astern braking her bulky progress into the narrow gap.
With his departure star astern and his destination star ahead, he could keep to his course.
In common with the ketch, the forward (main) mast is higher than the mizzenmast, but the mizzenmast of a yawl is placed astern of the rudder post, while that of the ketch is closer amidships.
One of these launches a sound wave from a point close to the keel; the second, a few metres ahead or astern, detects this wave and measures the time required for it to traverse the known distance.
The first known castles are shown amidships or astern on Roman ships, to afford vantage points in sea skirmishes.
Ahead of him is Ger O'Rourke's Dutch-backed Delta Lloyd, which, as ABN Amro 1 won the race last time, but this time 48 miles astern in just 48 hours.
The net gain of 46 seconds was just too big a task for Oracle, which finally crossed the line 47 seconds astern.
Completing the first seven days at sea, he had re-established a cushion of 20 miles over Torben Grael in Ericsson 4, with the Nordic crew of Ericsson 3 a further 14 miles astern in what were still fast but tricky wind patterns.
As the German battle cruisers and destroyers steamed forward, the German battleships astern became confused and disorganized in trying to execute their reverse turn.
While standing watch on the bridge during the early hours of that day, one of the officers of the Ramapo saw, in the moonlight, a great wave rising astern to a level above an iron strap on the crow's-nest of the mainmast.
Each time a boat backed out of the ferry port, the captain let loose one long blast of the horn, followed by three shorter blasts, which, according to Rule 34(a)(i), means "I am operating astern propulsion".
