Editing Naval architecture (section)

===Structures===
{{See also|Superstructure|Hull (watercraft)|l2=Hull design|Shell plating}}
[[File:Diagram of US Navy WWII destroyer escort.png|thumb|upright=1.35|right|Cutaway of the structure of a US Navy WWII destroyer escort]]
[[Image:Plate Strakes.PNG|thumb|260px|right|An [[autoCAD]] drawing of the various [[shell plating]] on a convention [[Hull (watercraft)|hull]].]]
[[Structural engineering|Structures]] involves selection of material of construction, [[structural analysis]] of global and local strength of the vessel, vibration of the structural components and structural responses of the vessel during [[Seakeeping|motions in seaway]]. Depending on type of ship, the structure and design will vary in what material to use as well as how much of it. Some ships are made from glass reinforced plastics but the vast majority are steel with possibly some aluminium in the superstructure.<ref name=":0" />

The complete structure of the ship is designed with panels shaped in a rectangular form consisting of steel plating supported on four edges. Combined in a large surface area the Grillages create the hull of the ship''',''' deck, and bulkheads while still providing mutual support of the frames. Though the structure of the ship is sturdy enough to hold itself together the main force it has to overcome is longitudinal bending creating a strain against its hull, its structure must be designed so that the material is disposed as much forward and aft as possible.<ref name=":0" />

The principal longitudinal elements are the deck, shell plating, inner bottom all of which are in the form of grillages, and additional longitudinal stretching to these. The dimensions of the ship are in order to create enough spacing between the stiffeners in prevention of buckling. Warships have used a longitudinal system of stiffening that many modern commercial vessels have adopted. This system was widely used in early merchant ships such as the [[SS Great Eastern]], but later shifted to transversely framed structure another concept in ship hull design that proved more practical. This system was later implemented on modern vessels such as tankers because of its popularity and was then named the  [[Isherwood System]].<ref name=":0" />

The arrangement of the Isherwood system consists of stiffening decks both side and bottom by longitudinal members, they are separated enough so they have the same distance between them as the frames and beams. This system works by spacing out the transverse members that support the longitudinal by about 3 or 4 meters, with the wide spacing this causes the traverse strength needed by displacing the amount of force the bulkheads provide.<ref name=":0" />