An LNS Approach for Container Stowage Multi-port Master Planning - Computational Logistics - page 37

Below deck, cell guides secure containers transversely. Containers on deck are
secured by lashing rods and twist locks with limited strength. Thus, container
weights must normally decrease upwardsinstacksondeck.Moreover,stack
heights must be under the vessel's minimum line of sight.

3 9 7 8 4 9

7 5 7

4 10 4

Line of sight

Bay Lashing bridge Waterline Station

Hatch cover

Fig. 1. Arrangement of container vessel bays. The vertical arrows show an example of
the resulting forces acting on the ship sections between calculation points (stations).
Single crane work hours for adjacent bays are shown at the top.

Stack

Stacks On Deck Bow

Fore Aft

12 3456

7 8

M

Metacentric

3
2
1

height

θ

Tiers
On
Deck

4 3 4

40' High−Cube

G Z

Buoyancy
force

4
3
2
1

2 1 2

Tiers
Below
Deck

Gravity

40' Reefer

force

20' Reefer

20'

12 3 4 5 6 7

Stern

Stacks Below Deck

( a ) ( b ) ( c )

Fig. 2. (a) A bay seen from behind. (b) A side view of a stack of containers. Power
plugs are usually situated at bottom slots. (c) Transverse stability.

A container ship must have sucient transverse stability . Figure 2 (c) shows a
cross section of a ship. For small inclination angles, the buoyancy force intersects
the center line in a fixed position called the metacenter , M [15]. The metacentric
height is the distance between M and G (the center of gravity). The ship must
have sucient GM to be stable. Maximum and minimum draft restrictions apply
due to port depths, working height of cranes, and the propeller. The trim is the
difference between the aft and fore draft and must be kept within a given span.
For a station position p ,the shear force is the sum of the resulting vertical forces
on vessel sections (see Figure 1) acting aft of p ,andthe bending moment is the
sum of these forces times the horizontal distance to them from p .Bothofthese
stresses must be within limits.
A stowage plan assigns the containers to load in a terminal to slots on the
vessel. In contrast, a master plan is the assignment of containers, grouped into