Upper deck stringer

The upper-deck stringer is the outboard strake of the strength deck, the plate that joins the deck to the sheer strake at the gunwale. It carries the highest hull-girder bending stress on the deck because it sits at the greatest distance from the neutral axis, so it is one of the strakes whose thickness drives the deck section modulus under IACS UR S11. The stringer-to-sheer-strake corner is a stress concentration and a fatigue-prone detail, often rounded or given a gunwale bar, and class rules restrict welding and notches there. On many ships the deck stringer and sheer strake are specified at a higher steel grade for crack-arrest at this corner.