Shell Plating
Shell Plating is the continuous steel skin that forms the watertight boundary of the hull — the bottom, bilge and side plating from the keel up to the sheer strake at deck level. It is welded to the frames and girders and carries the water pressure and the loads of the sea into the ship structure.
The plating is arranged in fore-and-aft rows called strakes, each with its own name (garboard, bilge, sheer, and so on), and its thickness is set by class rules and increased in highly stressed areas. Corrosion wastage of the shell plating is a primary focus of thickness measurement at survey.
The shell plating is literally what keeps the sea out and carries the hull loads, so its thickness and soundness are fundamental to the safety of the ship. Wastage below the allowable limits means steel renewal — which is why the shell is gauged extensively at special surveys.
What is a strake of shell plating?
A fore-and-aft row of shell plates. Strakes are named by position — the garboard strake next to the keel, the sheer strake at the deck edge, and others between — each sized for the loads it carries.