The phrase "aft beam" is correct and usable in written English.
It is typically used in nautical or maritime contexts to refer to a structural component located at the rear of a ship or boat.
Example: "The aft beam of the vessel was reinforced to improve stability during rough seas."
Alternatives: "rear beam" or "stern beam".
Petropavlovsk was 300 feet long between perpendiculars, with a beam of and a draft of 22 feet (forward) and 24 feet (aft).
The gun ports were 30 inches wide which allowed each gun to fire 30° fore and aft of the beam.
In addition, the ship was fitted with an anti-torpedo bulge that stretched between her bridge and aft superstructure to increase her beam and thus her stability.
The 15-inch guns could traverse 30° forward of the beam and 28° aft and the 11-inch Dahlgrens could bear 28° to both sides.
The Dunia Baru boasts six extremely spacious en-suite double berths, and there is a wonderfully sumptuous full-beam master-suite on the aft upper-deck, with a large bathroom, and a day-bed sundeck.
Similar to the pure spotlight mode, azimuth beam is steered from fore to aft during the overall acquisition time in the sliding spotlight mode.
They were even careful not to say for certain whether they were looking at the prow or the stern of the vessel, though the fanlike array of beams seemed to suggest that the aft (rear) portion of the ship was exposed.
Armament was heavy for her size, with the main battery consisting of a pair of 10-inch 30-caliber breech-loading (BL) guns mounted in individual barbettes fore and aft, capable of training up to 30 degrees abaft of the beam.
Different from conventional stripmap mode with a fixed azimuth beam pointing direction, azimuth beam is steered from fore to aft during the whole acquisition time in the sliding spotlight mode.
Four 21 inches submerged torpedo tubes were fitted on the beam, one pair port and starboard forward of 'A' barbette and aft of 'X' barbette.
