• No results found

General, Definitions, Documentation

In document Indian Coast Guard Ships (Page 49-52)

1.1 Scope and application

1.1.1 The scantlings of various hull members are to be based on the design values of accelerations given in Section 2 and the local loads due to lateral pressures, impact pressures, liquid pressures in tanks, dry cargo, stores etc. given in Section 3. Longitudinal strength is to be investigated as per Chapter 5 and 6.

1.1.2 Speed reduction may be considered in heavy seas to limit the accelerations to the design values. A table giving the allowable speeds versus significant wave heights is to be appended to the class certificate and also to be posted in the wheelhouse.

1.1.3 Alternative methods of load estimation based on model tests, full scale measurements or accepted theories may be specially considered.

1.2 Definitions

1.2.1 The forward perpendicular, F.P., is the perpendicular drawn at the forward end of the length defined in chapter 1, 2.6.18.

1.2.2 The after perpendicular, A.P. is the perpendicular drawn at the aft end of the length defined in Chapter 1, 2.6.18.

1.2.3 “Amidship” is at 0.5L aft of the F.P.

1.2.4 Depth, D, is the moulded depth [m], measured amidships from top of the keel to the moulded deck line of the uppermost continuous deck at side.

1.2.5 Draught, T, is the moulded draught amidships corresponding to the fully loaded waterline with the Ship floating at rest, [m].

1.2.6 The block coefficient, Cb, is the moulded block co-efficient calculated as follows:

1.2.7 Bw is the greatest moulded breadth of the hull(s) in m at the fully loaded waterline, with the Ship at rest.

1.2.8 Wave factor -

CW = 0.0856 L for L ≤ 90 m

= 10.75 - [(300-L)/100]3/2 for L > 90 m

Wave factor CW for service area notations would be reduced as follows:

Notation Reduction factor

RS0 1.0

RS1 0.8

RS2 0.6

RS3 0.35

1.2.9 For definitions of breadth B, maximum service speed V, displacement ∆ and other terms see Chapter 1, Sec.2.6.

1.3 Structural terms

1.3.1 The general terms used in the Rules for various structural components of the Ships are defined as under:

Strength Deck : In general, the uppermost continuous deck. Where a superstructure deck has within 0.4L amidships, a continuous length equal to or greater than (1.5B + 3H), it is to be regarded as the strength deck instead of the covered part of the uppermost continuous deck. (H is the height of the superstructure [m]).

Freeboard Deck : The freeboard deck is normally the uppermost complete deck exposed to weather and sea, which has permanent means of closing all openings in the weather part and below which all openings on the sides of the ship are fitted with means for watertight closing.

Superstructure : A decked structure on freeboard deck extending from side to side of the ship or with the side plating not inboard of shell plating by more than 4 percent of the breadth B.

Deckhouse : A decked structure above the freeboard deck with the side plating being inboard of the shell plating by more than 4 percent of the breadth B.

Girder : A collective term for the primary supporting members, other terms include:

− Transverse – transverse girder under the deck

− Web frame – side vertical girder

− Stringer – horizontal girder

− Floor – bottom transverse girder.

Stiffener : A collective term for secondary supporting members, other terms being

− Frame

− Reverse frame – transverse stiffener on the inner bottom

− Horizontal or vertical bulkhead stiffener.

w T B L

T draught at

m nt displaceme

moulded 3]

[ Cb =

1.4 Documentation

1.4.1 Documents as listed in 1.4.2 to 1.4.4 below are to be submitted in triplicate, one copy of which shall be returned.

1.4.2 The following supporting plans and calculations are to be submitted for information:

− General arrangement

− Tank plan

− Lines plan and hydrostatic curves or tables

− Docking plan

− Operating manuals.

1.4.3 The following additional information is to be submitted for the purpose of strength calculations:

− Maximum values of still water bending moments and shear forces

− Lightship weight and its longitudinal distribution

− Bonjeans data

− Masses and unbalanced moments of heavy machinery components e.g. engines, cranes, winches etc.

1.4.4 Plans as indicated in Table 1.4.4 are to be submitted for approval, as relevant.

Table 1.4.4 : Hull plans for approval

Plan Including information on

Loading manual and stability information booklets

Details of loading in all contemplated loading conditions and resulting SWBM, SF and Torsional Moments (TM)

Intact and damage stability analysis Midship section

Other transverse sections Longitudinal sections and decks Cross deck structure in case of multi- hull vessels

Shell expansion and frame plan

Main dimensions, displacements, maximum speed

Design values of vertical accelerations at c.g and wave height, speed reductions, if any

Equipment specification

Complete class notation applied for Spacing of stiffeners

Deck loads, if other than those specified in the Rules Opening on the deck

Minimum ballast draught(s)

Extent of flat part of bottom forward Openings of the shell

Material grades

Double bottom Indication of access

Height and location of overflows Loading on inner bottom

Watertight subdivision bulkheads and watertight tunnels

Openings and their closing appliances Aft-end structure

Propeller shaft brackets Aftpeak structure

Propeller outline Propeller thrust

Structural details in way of rudder and propeller bearings Engine room structure

Machinery foundations

Type, power and r.p.m. of propulsion machinery Weight of machinery, boilers, etc.

Fore-end construction Fore peak structure

Openings on non-watertight bulkheads and diaphragm plates

Plan Including information on Oil tight/water tight and partition

bulkheads in tanks

Intended tank contents and their densities Height and location of overflow/air pipes Tanks intended to be partially filled Corrosion protection, if any

Superstructures deckhouses and machinery casings

Height of sills from deck and closing appliances for companion ways, expansion joints if provided

Hatchways Hatch covers Bow and stern doors Side ports

Position and type

Loads if different from those specified in the rules

Sealing and securing arrangement, spacing of bolts or wedges Rudder stock and tiller

Steering gear arrangement

Speed of the ship (ahead and astern)

Material of bearings, coupling bolts, stock and the locking device rudder carrier

Masts & derrick posts

Support structure for masts, derrick posts, cranes, RAS points,

machinery lifting points.

derrick length and loading

dimensions and positions of stays quality of material

Helideck All up weight of Helicopter

Gun seatings Gun recoil forces

Anchoring and mooring arrangement, hawse pipes

Trim flaps or foils structure Details of attachment to hull

Bilge keel Material grade

Testing plan of tanks and bulkheads Welding details

Shipping/ Unshipping routes of major machinery

Details of all hard and soft patches Structural Fire Protection

Escape Routes

Note : One drawing may contain more than one of the items from each group

Section 2

In document Indian Coast Guard Ships (Page 49-52)