Verticalstiffenersarefittedtothetransversewatertightbulkheadsofaship,thespan being less in this direction and the stiffener therefore having less tendency to deflect under load. Stiffening is usually in the form of welded inverted ordinary angle bars, or offset bulb plates, the size of the stiffener being dependent on the unsupported length, stiffener spacing, and rigidity of the end connections. Rigidity of the end connections will depend on the form of end connection, stiffeners in holds being bracketed or simply directly welded to the tank top or underside of deck, whilst upper tween stiffeners need nothave anyconnection at all (seeFigure18.1). Vertical stiffenersmay besupportedbyhorizontalstringers,permittingareductioninthestiffenerscantlingas a result of the reduced span. Horizontal stringers are mostly found on those bulkheads forming the boundaries of a tank space, and in this context are dealt with later.