many modern ships have cofferdams ( double bulkheads) when I served my apprenticeship as a shipwright we used to build obo's refrigeration ships and oil tankers the first ship I worked on was the liverpool bridge or the devonshire as she later became known. this was one of the largest ship ever made and you could fit two football pitches on the decks. often holds would have stringer plates as I recall these were at various levels and ran horizontally at each corner of the hold.
LIVERPOOL BRIDGE/DERBYSHIRE (4) was built in 1976 by Swan, Hunter Shipbuilders Ltd at Haverton-on-Hill with a tonnage of 91655grt, a length of 965ft 1in, a beam of 145ft 2in and a service speed of 15.5 knots. Launched on the 5th December 1975 she was the sixth and largest OBO built at Swan, Hunter's Haverton-on-Hill yard. When she was delivered to Bibby Tankers Ltd in the following June for charter to the Seabridge Consortium she was the largest ship ever owned by the Bibby Group.