The meaning of ?gmanhole?h is exactly what RonBee said. In modern cargo ships there are a lot of manholes to access tanks. Starboard and port decks are fitted with side tanks as well as on tanktops - The plating forming the top of the double bottom. It is fitted to the tops of the floor plates, longitudinals and center keelson, and makes a complete inner skin extending over the bottom and sometimes up the sides of a vessel. Link to explanation of tanktop: http://titanic-model.com/glossary/p.shtml
I think, if SS Titanic was fitted with double bottoms and bulkheads -A term applied to any of the partition walls used for subdividing the interior of a ship into the various compartments. The main partition walls also serve as strength members of the ship÷Ő structure and as a protection against water passing from one compartment to another - it would not have sunk so fast. Link to explanation of bulkhead: http://titanic-model.com/glossary/b.shtml
Just remember it as a hole for a man.
By the way, women in USA have been fighting for sexes equality. Chairman becomes chairwomen, now chairperson.
Should we change ?gmanhole?h, to ?gwomanhole?h, or ?gpersonhole?h? (just kidding)