HULL FRAMING HULL FRAMING SYSTEMSSYSTEMS

GROUP CGROUP C

DMS(DO)DMS(DO)

QUESTIONQUESTION

Describe and compare transverse and Describe and compare transverse and longitudinal framing systems and explain the longitudinal framing systems and explain the

need for combination framing system.need for combination framing system.

FRAMING SYSTEMSFRAMING SYSTEMS

There are three possible ways to fit the secondary supporting There are three possible ways to fit the secondary supporting members:members:

Transverse Framing SystemTransverse Framing System Longitudinal Framing SystemLongitudinal Framing System Combined or Mixed Framing SystemCombined or Mixed Framing System

TRANSVERSE FRAMING TRANSVERSE FRAMING SYSTEMSYSTEM

The hold frames are fitted The hold frames are fitted transverselytransversely

Longitudinal deck girders support Longitudinal deck girders support the transverse deck beamsthe transverse deck beams

Longitudinal strength in a Longitudinal strength in a transversely framed ship is transversely framed ship is provided by:provided by:

The centre girder, the shell plating The centre girder, the shell plating and inner bottom platingand inner bottom plating

By the deck plating outboard of By the deck plating outboard of hatch and machinery casing hatch and machinery casing openingsopenings

By a number of large, widely By a number of large, widely spaced longitudinal members e.g. spaced longitudinal members e.g. longitudinal deck girderslongitudinal deck girders

TRANSVERSE FRAMED OIL TRANSVERSE FRAMED OIL TANKERTANKER

LONGITUDINAL FRAMING LONGITUDINAL FRAMING SYSTEMSYSTEM

All secondary supporting members are All secondary supporting members are fitted the longitudinal direction and are fitted the longitudinal direction and are known as longitudinalsknown as longitudinals

The system consists of many small, The system consists of many small, closely spaced longitudinals supporting closely spaced longitudinals supporting the plating directly and being supported the plating directly and being supported in turn by a few largely spaced in turn by a few largely spaced longitudinalslongitudinals

It is in tankers that this system in its It is in tankers that this system in its purest form is employedpurest form is employed

They also contribute to the longitudinal They also contribute to the longitudinal strength of the ship, making the strength of the ship, making the longitudinal framing system more longitudinal framing system more structurally efficient than the transverse structurally efficient than the transverse systemsystem

LONGITUDINALLY FRAMED OIL LONGITUDINALLY FRAMED OIL TANKERTANKER

COMPARISONCOMPARISON No contribution to the ship’s resistance No contribution to the ship’s resistance

to longitudinal bending.to longitudinal bending.

Not optimal from the standpoint of Not optimal from the standpoint of structural efficiency, i.e. achieving the structural efficiency, i.e. achieving the required strength for the least weight.required strength for the least weight.

More resistant to buckling between More resistant to buckling between longitudinal stiffeners when subjected longitudinal stiffeners when subjected to compressive stresses while to compressive stresses while bending in seaway.bending in seaway.

Superior structural efficiency because Superior structural efficiency because most of the plating stiffeners are in most of the plating stiffeners are in the fore and aft direction.the fore and aft direction.

The intrusion of deep webs into prime cargo spaces for ships carrying packaged The intrusion of deep webs into prime cargo spaces for ships carrying packaged

cargo is a disadvantage of longitudinal framing system.cargo is a disadvantage of longitudinal framing system.

As the hull narrows toward bow and stem, the girth necessary reduces.As the hull narrows toward bow and stem, the girth necessary reduces.

Difficulties in construction arise when the longitudinal frames converge so closely.Difficulties in construction arise when the longitudinal frames converge so closely.

For this reason, transverse framing is usually resorted to at the bow and stem of For this reason, transverse framing is usually resorted to at the bow and stem of

longitudinally framed ships.longitudinally framed ships.

COMBINED FRAMING SYSTEMCOMBINED FRAMING SYSTEM

A combination of both transverse and A combination of both transverse and longitudinal framing is adopted in the longitudinal framing is adopted in the same cross section of the ship.same cross section of the ship.

Longitudinal framing is used in the Longitudinal framing is used in the bottom and decks.bottom and decks.

This has the advantage of extra This has the advantage of extra longitudinal strength and resistance longitudinal strength and resistance to compressive plate buckling.to compressive plate buckling.

Transverse framing is used in the Transverse framing is used in the sides.sides.

This precludes the need for deep This precludes the need for deep webs that might inhibit efficient cargo webs that might inhibit efficient cargo stowage.stowage.

COMPOSITELY FRAMED OIL COMPOSITELY FRAMED OIL TANKERTANKER

REFERENCESREFERENCES

Ship Powering and Construction NotesShip Powering and Construction Notes Naval Architecture Lectures on the webNaval Architecture Lectures on the web

http://http://web.nps.navy.mil/~me/tsse/NavArchWeb/lectweb.nps.navy.mil/~me/tsse/NavArchWeb/lectures.htmures.htm//