4.3.1 For passenger craft, superimposed vertical
accelerations above 1.0 g at longitudinal centre of gravity should
be avoided unless special precautions are taken with respect to passenger
safety.
4.3.2 Passenger craft should be designed for the
collision load with respect to the safety in, and escape from, the
public spaces, crew accommodation and escape routes, including in
way of life-saving appliances and emergency source of power. The size
and type of craft together with speed, displacement and building material
should be taken into consideration when the collision load is determined.
The collision design condition should be based on head-on collision
at operational speed with a vertical rock with maximum 2 m height
above the waterline.
4.3.3 Taking into consideration the provisions
of 4.3.2, the collision load should be determined by:
where the load P should be taken as the lesser of:
|
P |
= |
460 (M.cL)⅔(E.cH)⅓ and
|
|
P |
= |
9000.M.cL (cH (T + 2))½
|
where the hull material factor M should be taken
as:
|
M |
= |
1.3 for high tensile
steel |
|
M |
= |
1.00 for aluminium
alloy |
|
M |
= |
0.8 for fibre
reinforced plastics |
where the length factor cL of the craft
is:
where the height factor cH of the craft
is:
| Factor cH
|
Catamaran/surface effect
ship
|
Monohull/hydrofoil
|
Air-cushion vehicle
|
| cH
|
|
|
|
| where: f=0 for
|
T + 2 < D - HT
|
T + 2 < D
|
-
|
| where: f=1 for
|
D > T + 2 ≥ D - HT
|
T + 2 ≥ D
|
HT > 2
|
| where: f=2 for
|
T + 2 ≥ D
|
-
|
HT
|
where the kinetic energy of the
craft at speed V is:
where the main particulars of the craft are:
|
L |
= |
craft length as
defined in chapter 1 (m) |
|
D |
= |
craft depth from
the underside of keel amidships to the top of the effective hull girder
(m) |
|
T |
= |
buoyancy tank
clearance to skirt tip (m, (negative)) for air-cushion vehicles; lifted
clearance from keel to water surface (m, (negative)) for hydrofoils,
and craft draught to the underside of keel amidships for all other
craft (m) |
|
HT
|
= |
minimum
height from tunnel or wet-deck bottom to the top of the effective
hull girder on catamarans and surface effect ships and D for air-cushion
vehicle (m) |
|
Δ |
= |
craft displacement,
being the mean of the lightweight and maximum operational weight (t) |
|
v |
= |
operational speed
of craft (m/s) |
|
g |
= |
gravitational
acceleration = 9.806 (m/s2
|
For hydrofoils, if the result is greater than the
deceleration, gcoll should be taken as:
where:
|
F |
= |
failure load of
bow foil assembly applied at the operational waterline (kN) |
4.3.4 As an alternative to the requirements of
4.3.3, collision deceleration may be determined by carrying out collision
load analysis of the craft in 4.3.3 accordance with the assumptions
of 4.3.2. If the collision accelerations are determined by both use
of the formula referred to in and the collision load analysis, the
lower resulting value may be used as the collision deceleration.
4.3.5 Compliance with the provisions of 4.1.5 and 4.3.1 should be shown for the actual
type of craft, as described in annex 8.
4.3.6 Limiting sea states for operation of the
craft should be given in normal operation condition and in the worst
intended conditions, at operational speed and at reduced speed as
necessary. Operational information should be available on board for
guidance, or the craft should have an instrument system for on-line
check of operational performance. As a minimum, the system should
measure accelerations in three axes close to the longitudinal craft
centre of gravity.