Stiffners:
Anything that is used solely to provide strength to a ship structure can be called a stiffner. These are secondary plates or sections which are attached to beam webs or flanges to stiffen them against out of plane deformations
A stiffner welded in longitudinal direction is called “Longitudinal stiffner”. Same way a stiffners welded in transverse direction is simply called “transverse stiffner”.
Girders
Girders are one form of longitudinal stiffners. It is a longitudinal member used in the construction of the bottom of a ship. They can be plate or beam and can be placed above the keel (centre girder) or spaced equal distances from it (side girders). They can be continuous or divided by floor sections (intercostal side girders)
Longitudinals
Longitudinal is a short name for longitudinal stiffners. These are mainly L shaped frames found on under decks, on side plating, on longitudinal bulkheads, on bottom platting and under the tank top.
Transverse
Transverse is the short name for “transverse stiffners”. Transverse found under the deck is called deck transverse and the bottom platform is called bottom transverse. Runs transversly but much heavier in construction than beams.
Similar stifners have different names in each plane see the table below
