Also known as: sl.
SL has various meanings in the Ordnance Survey category. Discover the full forms, definitions, and usage contexts of SL in Ordnance Survey.
An opening in the lower part of a bulkhead fitted with a sliding watertight gat or door having an operating rod extending to the upper deck or decks. These openings are useful in center line bulkheads, as in case of damage to one side of the ship the water may be quickly admitted to the other side before the ship is dangerously listed.
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