Topic - 16 Hull structures and arrangement (PART-II)

       Decks

     Deck plating thickness

Thickness of Strength Decks with Longitudinal Beams, Strength Decks with Transverse Beams in Vessel ____ m  or Less and Forecastle Decks in Vessel over ____ m 

t = 0.009s + 2.4 mm for s ≤ 760 mm   

                                 

                                                      =____ mm

Thickness of Exposed Strength Decks within Line of Openings, Forecastle Decks in Barges of 122 m (400 ft) in Length or Less

t = 0.01s+ 0.9 mm for s ≤ 760 mm   

                                   = _____ mm

Finalized Deck Plating thickness = _____  mm

 Deck Plating at Ends

The thickness of the deck plating forward or aft of 0.1L from the ends is not to be less than 0.01 mm for each millimeter of frame spacing (0.01 in. for each inch of frame spacing).

S (frame spacing) = 708 mm hence t=0.01×708 =7.08

In way of deck cargo, the requirements of 3-2-3/1.5 also apply. Exposed freeboard deck plating forward of 0.05L from the forward perpendicular is also not to be less in thickness than given by the following equation:

t = 0.03L + 0.0036s + 2.8 mm  

                                       = _____  mm

Finalized Deck Plating thickness = ______ mm

Main Framin

     Proportions

Deck girders, chords and transverse and bottom/side girders, chords and transverses are to have proportions complying with the following:

Ø  Deck girders, chords and transverses are to have a depth of not less than 58.5 mm per meter of span l (0.7 in. per foot of span l).

           Length of span =  _____m

           1m -  ____mm

           For ___ m –  ___mm

Finalized depth of the deck girders =____ mm

Ø  Deck girders, chords and transverses in tanks are to have depth of not less than 83.5 mm per meter of span l (1 in. per foot of span l).

           1m – _____ mm

                    For 2.832 span min depth of the deck girder =_____ mm

Finalized depth of the deck girders in tanks =_____ mm

Ø  Bottom and side girders, chords and transverses are to have a depth of not less than 125 mm per meter of span l (1.5 in. per foot of span l).

                     For 2.832 span min depth of the deck girder = _____mm

Finalized depth of the bottom and side girders =______ mm

Since the Angle bar dimensions are taken to be 4 inches, the deck girder, deck girder at the tanks and for the bottom and side girders, the depth is taken to be nearly 14 1/16 inches. So that the cutout made is less than 1/3^rd the depth of the girder.

Stiffeners

Where the depth/thickness ratio of the web portion of girders, chords and transverses exceeds 80, stiffeners are to be provided aligning with each longitudinal or transverse frame or horizontal or vertical bulkhead stiffener, as appropriate. In addition, where the depth/thickness ratio exceeds 200, a stiffener is to be fitted parallel to the flange at about 25% of the depth of the web from the flange.