Section 2 Nomenclature and design factors
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Clasifications Register Rules and Regulations - Rules and Regulations for the Classification of Special Service Craft, July 2022 - Part 5 Design and Load Criteria - Chapter 3 Local Design Criteria for Craft Operating in Non-Displacement Mode - Section 2 Nomenclature and design factors

Section 2 Nomenclature and design factors

Parent topic: Chapter 3 Local Design Criteria for Craft Operating in Non-Displacement Mode

2.1 Nomenclature

2.1.1 The nomenclature used in this Chapter is given below:

P p = pitching pressure, see Pt 5, Ch 2, 4.4 Hydrodynamic wave pressure
P fb = impact pressure for craft supported by hydrodynamic lift provided by foils or other lifting devices, see Pt 5, Ch 2, 5.3 Impact pressure for craft with foils and lifting devices
P dhp = deckhouse, bulwalks and superstructure pressure, see Pt 5, Ch 2, 7.1 Deckhouses, bulwarks and superstructures
P bh = watertight and deep tank bulkhead pressure, see Pt 5, Ch 2, 7.2 Watertight and deep tank bulkheads
P pc = impact pressure acting on the cross-deck structure, see Pt 5, Ch 2, 6.2 Impact pressure
P wl = pressure on weather deck, see Pt 5, Ch 2, 4.5 Pressure on weather and interior decks
P BP = design pressure for bottom plating
P BF = design pressure for bottom stiffening
P SP = design pressure for side shell plating
P SF = design pressure for side shell stiffening
P CP = design pressure for cross-deck plating
P CF = design pressure for cross-deck stiffening
P WDP = design pressure for weather deck plating
P WDF = design pressure for weather deck stiffening
P CRP = design pressure for coachroof plating
P CRF = design pressure for coachroof stiffening
P IDP = design pressure for interior deck plating
P IDF = design pressure for interior deck stiffening
P IBP = design pressure for inner bottom plating
P IBF = design pressure for inner bottom stiffening
P DHP = design pressure for deckhouse, bulwarks and superstructures plating and windows
P DHF = design pressure for deckhouse, bulwarks and superstructure stiffening
P BHP = design pressure for bulkheads
P CDP = design pressure for cargo deck plating

Δ and Γ are defined in Pt 5, Ch 2, 2.2 Symbols 2.2.2 and Pt 5, Ch 2, 2.1 Parameters to be used for the determination of load and design criteria 2.1.17

T, L R and B are as defined in Pt 3, Ch 1, 6.2 Principal particulars.

2.1.2 The unit for pressure is kN/m2.

2.1.3 The design pressure, P, used in the scantling formulae given in Pt 3 General Requirements and Constructional Arrangements, Pt 6 Hull Construction in Steel, Pt 7 Hull Construction in Aluminium and Pt 8 Hull Construction in Composite is to be taken as equal to the appropriate value as defined in this Chapter.

2.2 Design factors

2.2.1 The design pressures on structural components are to be calculated taking into consideration the following factors:

  1. Hull notation assigned as defined in Pt 1, Ch 2, 3.4 High speed craft and light displacement craft notations.

  2. Service area restriction notation assigned as defined in Pt 1, Ch 2, 3.5 Service area restriction notations.

  3. Service type notation assigned as defined in Pt 1, Ch 2, 3.6 Service type notations.

  4. Craft type notation assigned as defined in Pt 1, Ch 2, 3.7 Craft type notations.

  5. Type of stiffening members.

2.2.2 In general, the design pressure, in kN/m2, for a particular structural component is to be determined as follows:

Design pressure = δf H f G f S f C f x load criterion

where
H f = hull notation factor given in Table 3.2.1 Hull notation factor, Hf
G f = service area restriction notation factor given in Table 3.2.2 Service area notation factor, G f
S f = service type factor notation given in Table 3.2.3 Service type notation factor, S f
C f = craft type notation factor given in Table 3.2.4 Craft type notation factor, C f
δf = stiffening type factor as given in Table 3.2.5 Stiffening type factor,

Table 3.2.1 Hull notation factor, Hf

Hull notation Factor
HSC 1,0
LDC 0,95

Note For a craft eligible for both HSC and LDC notation, the higher value is to be used. H f is to be taken as 1,0 for a craft not eligible for either the HSC or the LDC notation.

Table 3.2.2 Service area notation factor, G f

Service area restriction notation Factor
G1, Zone 3 0,6
G2, Zone 2 0,75
G2A, Zone 1 0,8
G3 0,85
G4 1,0
G5 1,2
G6 1,25

Table 3.2.3 Service type notation factor, S f

Service type notation Factor
Cargo (A) 1,0
Cargo (B) 1,1
Passenger 1,0
Passenger (A) 1,0
Passenger (B) 1,1
Patrol 1,2
Pilot 1,25
Yacht 1,1
Workboat 1,25

Table 3.2.4 Craft type notation factor, C f

Craft type notation Factor
Catamaran 1,0
Hydrofoil 1,1
Mono 1,0
Multi 1,1
RIB 1,15
SES 1,0
SWATH 1,0

Table 3.2.5 Stiffening type factor,

Type δf
Primary stiffening members and transverse frames 0,5
Secondary and local stiffening members
Transverse beams 		0,8
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