Ingangsdatum: 01-07-1996 
Geldig tot en met: 26-05-2002 
7.1  Assumption of external forces 
External forces to a cargo unit in longitudinal,
                            transverse and vertical direction should be obtained using the formula:
                                
F
(x,y,z) = m · a
(x,y,z) +
                                F
w(x,y) + F
s(x,y) F
(x,y,z) =
                            longitudinal, transverse and vertical forces 
m = mass
                            of the unit 
a
(x,y,z) = longitudinal,
                            transverse and vertical acceleration (see table 2) 
F
w(x,y) = longitudinal and transverse force by wind
                            pressure 
F
s(x,y) = longitudinal and
                            transverse force by sea sloshing 
The basic
                            acceleration data are presented in Table 2. 
| Transverse
                                        acceleration av in m/ | Longitudinal acceleration ax in m/sec2 | 
| on deck high | 7.1 | 6.9 | 6.8 | 6.7 | 6.7 | 6.8 | 6.9 | 7.1 | 7.4 | 3.8 | 
| on deck low | 6.5 | 6.3 | 6.1 | 6.1 | 6.1 | 6.3 | 6.5 | 6.7 | 2.9 | 2.9 | 
| tween deck | 5.9 | 5.6 | 5.5 | 5.4 | 5.4 | 5.5 | 5.6 | 5.9 | 6.2 | 2.0 | 
| lower hold | 5.5 | 5.3 | 5.1 | 5.0 | 5.0 | 5.1 | 5.3 | 5.5 | 5.9 | 4.5 | 
| 0 | 0.1 | 0.2 | 0.3 | 0.4 | 0.5 | 0.6 | 0.7 | 0.8 | 0.9 | L | 
| Vertical acceleration ax in m/sec2 | 
|  | 7.6 | 6.2 | 5.0 | 4.3 | 4.3 | 5.0 | 6.2 | 7.6 | 9.2 |  | 
 Table 2: Basic acceleration
                            data (Figure) 
Remarks: 
The given transverse acceleration figures include
                            components of gravity, pitch and heave parallel to the deck. The given
                            vertical acceleration figures do not include the static weight
                            component. 
The basic acceleration data are to be
                            considered as valid under the following operational conditions: 
1. Operation in unrestricted area. 
2. Operation during the whole year. 
3. Duration of
                            the voyage is 25 days. 
4. Length of the ship is 100 m.
                                
5. Service speed is 15 knots. 
6.
                            B/GM greater or equal to 13. (B: breadth of ship, GM: metacentric
                            height) 
For operation in a
                            restricted area reduction of these figures may be considered taking also
                            into account the season of the year and the duration of the voyage. 
For ships of a length other than 100
                            m and a service speed other than 15 knots, the acceleration figures
                            should be corrected by a factor given in Table 3.
| Length speed
 | 50 | 60 | 70 | 80 | 90 | 100 | 120 | 140 | 160 | 180 | 200 | 
| 9
                                        kn | 1.20 | 1.09 | 1.00 | 0.92 | 0.85 | 0.79 | 0.70 | 0.63 | 0.57 | 0.53 | 0.49 | 
| 12 kn | 1.34 | 1.22 | 1.12 | 1.03 | 0.96 | 0.90 | 0.79 | 0.72 | 0.65 | 0.60 | 0.56 | 
| 15 kn | 1.49 | 1.36 | 1.24 | 1.15 | 1.07 | 1.00 | 0.89 | 0.80 | 0.73 | 0.68 | 0.63 | 
| 18 kn | 1.64 | 1.49 | 1.37 | 1.27 | 1.18 | 1.10 | 0.98 | 0.89 | 0.82 | 0.76 | 0.71 | 
| 21 kn | 1.78 | 1.62 | 1.49 | 1.38 | 1.29 | 1.21 | 1.08 | 0.98 | 0.90 | 0.83 | 0.78 | 
| 24 kn | 1.93 | 1.76 | 1.62 | 1.50 | 1.40 | 1.31 | 1.17 | 1.07 | 0.98 | 0.91 | 0.85 | 
 Table 3: Correction factors for
                            length and speed 
In addition for
                            ships with B/GM less than 13, the transverse acceleration figures should
                            be corrected by a factor given in Table 4.
| B/GM | 7 | 8 | 9 | 10 | 11 | 12 | 13 or
                                        above | 
| on deck high | 1.56 | 1.40 | 1.27 | 1.19 | 1.11 | 1.05 | 1.00 | 
| on deck low | 1.42 | 1.30 | 1.21 | 1.14 | 1.09 | 1.04 | 1.00 | 
| tween deck | 1.26 | 1.19 | 1.14 | 1.09 | 1.06 | 1.03 | 1.00 | 
| lower hold | 1.15 | 1.12 | 1.09 | 1.06 | 1.04 | 1.02 | 1.00 | 
 Table 4: Correction factors for B/GM <
                                13
The following cautions should be
                            observed: 
In the case of marked roll resonance with
                            amplitudes above +/- 30 degrees, the given figures of transverse
                            acceleration may be exceeded. Effective measures should be taken to
                            avoid this condition. 
In case of heading the seas at
                            high speed with marked slamming shocks, the given figures of
                            longitudinal and vertical acceleration may be exceeded. An appropriate
                            reduction of speed should be considered. 
In the case of running before large stern or aft
                            quartering seas with a stability, which does not amply exceed the
                            accepted minimum requirements, large roll amplitudes must be expected
                            with transverse accelerations greater than the figures given. An
                            appropriate change of heading should be considered. 
Forces by wind and sea to cargo units above the
                            weather deck should be accounted for by a simple approach: 
- force
                            by wind pressure 1 kN per m
2- force be sea sloshing 1 kN per m
2
                            Sloshing by sea can induce forces much greater than the figure given
                            above. This figure should be considered as remaining unavoidable after
                            adequate measures to prevent overcoming seas. 
Sea sloshing forces need only be applied to a height
                            of deck cargo up to 2 metres above the weather deck or hatch top. 
For voyages in restricted area sea
                            sloshing forces may be neglected. 
7.2 Balance of forces and moments 
The
                            balance calculation should preferably be carried out for 
- transverse sliding in port and starboard direction
                                
- transverse tipping in port and starboard
                            direction 
- longitudinal sliding under conditions of
                            reduced friction in forward and aft direction. 
In case of symmetrical securing arrangements one
                            appropriate calculation is sufficient. 
7.2.1 Transverse sliding 
The
                            balance calculation should meet the following condition (see also Fig.
                            1): 
 F
y ≤ μ · m · g + CS
1 · f
1 +
                                CS
2 · f
2 + ··· + CS
n ·
                                f
n where 
 n is the number of lashings
                            being calculated 
 Fy is transverse force from load
                            assumption (kN) 
 my is friction coefficient 
 (my = 0.3 for steel-timber or steel-rubber) 
 (my = 0.1 for steel-steel dry) 
 (my
                            = 0.0 for steel-steel wet) 
 m is mass of cargo unit
                            (t) 
 g is gravity acceleration of earth = 9.81
                            m/sec**2 
 CS is calculated strength of transverse
                            securing devices (kN) 
 f is function of my and
                            vertical securing angle alpha (see Table 5) 

Figure 1: Balance of transverse forces 
A vertical securing angle alpha
                            greater than 60 degrees will reduce the effectiveness of this particular
                            securing device in respect to sliding of the unit. Disregarding of such
                            devices from the balance of forces should be considered, unless the
                            necessary load is gained by the imminent tendency to tipping or by a
                            reliable pretensioning of the securing device which includes maintaining
                            the pretension throughout the voyage. 
Any horizontal securing angle, i. e. deviation from the transverse
                            direction, should not exceed 30 degrees, otherwise an exclusion of this
                            securing device from the transverse sliding balance should be
                            considered. 
| alpha (degrees) μ
 | -30 | -20 | -10 | 0 | 10 | 20 | 30 | 40 | 50 | 60 | 70 | 80 | 90 | 
| 0.3 | 0.72 | 0.84 | 0.93 | 1.00 | 1.04 | 1.04 | 1.02 | 0.96 | 0.87 | 0.76 | 0.62 | 0.47 | 0.30 | 
| 0.1 | 0.82 | 0.91 | 0.97 | 1.00 | 1.00 | 0.97 | 0.92 | 0.83 | 0.72 | 0.59 | 0.44 | 0.27 | 0.10 | 
| 0.0 | 0.87 | 0.94 | 0.98 | 1.00 | 0.98 | 0.94 | 0.87 | 0.77 | 0.64 | 0.50 | 0.34 | 0.17 | 0.00 | 
 Table 5:
                            f-values as function of alpha and μ / Remark: f = μ * sin(alpha) +
                            cos(alpha) 
7.2.2 Transverse
                            tipping 
This balance calculation should meet the
                            following condition (see also Fig.2); 
 F
y · a ≤ b · m ·
                            g + CS
1 · c
1 + CS
2 · f
2 +
                            ··· + CS
n · c
n F
y, m, g, CS, n are
                            explained under 7.2.1 
 a is lever-arm of tipping (m)
                            (see Fig.2) 
 b is lever-arm of stableness (m) (see
                            Fig.2) 
 c is lever-arm of securing force (m) (see
                            Fig.2) 

Figure 2: Balance of transverse moments 
7.2.3 Longitudinal sliding
                                
Under normal conditions the transverse securing
                            devices provide sufficient longitudinal components to prevent
                            longitudinal sliding. If in doubt, a balance calculation should meet the
                            following condition: 
 F
x ≤ μ · (m · g · F
z) +
                                CS
1 · f
1 + CS
2 · f
2 +
                            ··· + CS
n · f
n where 
 Fx is
                            longitudinal force from load assumption (kN) 
 n, my m,
                            g are as explained under 7.2.1 
 Fz is vertical force
                            from load assumption (kN) 
 CS is calculated strength
                            of longitudinal securing devices (kN) 
Remark: Longitudinal components of transverse securing devices should
                            not be assumed greater than 0.5 * CS. 
 Explanations and interpretation
                                to the "Methods to assess the efficiency of securing arrangements
                                for non-standardized cargo" 1.
Explanations and interpretation
                                to the "Methods to assess the efficiency of securing arrangements
                                for non-standardized cargo" 1. The exclusion from the
                            scope of application of the methods of very heavy units as carried under
                            the provisions of Chapter 1.8 of the Code should be understood to
                            accommodate the possibility of adapting the stowage and securing of such
                            units to specifically determined weather- and sea-conditions during
                            transport. The exclusion should not be understood as restriction of the
                            methods to units up to a certain mass or dimension. 
2. The acceleration figures given in
                            Table 2 in combination with the correction factors represent peak values
                            on a 25-day voyage. This does not imply that peak values in x-, y- and
                            z-direction occur simultaneously with the same probability. It can be
                            generally assumed that peak values in the transverse direction will
                            appear in combination with less than 60% of the peak values in
                            longitudinal and vertical direction. 
Peak values in longitudinal and vertical direction may join more
                            closely because they have common source of pitching and heaving 
3. The advanced calculation
                            method uses the "worst case approach". That is expressed clearly by the
                            transverse components of simultaneous vertical accelerations.
                            Consequently there is no need to consider vertical accelerations
                            separately in the transverse balances of forces and moments. These
                            simultaneously acting vertical accelerations create an apparent increase
                            of weight of the unit and thus improve the friction in the balance of
                            forces, respectively the moment stableness in the balance of moments.
                            For this reason there is no reduction of the normal force m . g due to
                            the present angle of heel. 
The
                            situation is different for the longitudinal sliding balance. The worst
                            case would be a peak value of the longitudinal force Fx accompanied by
                            an extreme reduction of weight through the vertical force Fz. 
4. The friction coefficients
                            shown in the methods are somewhat reduced against appropriate figures in
                            other publications. The reason for this should be seen in various which
                            may appear in practical shipping as moisture, grease oil, dust and other
                            residues, vibration of the ship 
There are certain stowage materials available which are said to
                            increase friction considerably. Extended experience with these materials
                            may bring additional coefficients into practical use. 
5. The principal way of calculating
                            forces within the securing elements of a complex securing arrangement
                            should necessarily include the consideration of 
-
                            Load-elongation behavior (elasticity) 
- Geometrical
                            arrangement (angles, length) 
- Pretension 
of each individual securing element
                                
This approach would require a
                            large volume of information and a complex, iterative calculation. Still
                            the results would be doubtful due to uncertain parameters. 
Therefore the simplified approach
                            was chosen with the assumption that the elements take an even load of CS
                            (calculation strength) which is reduced against the MSL (maximum
                            securing load) by the safety factor 1.5 
6. When employing the advanced calculation
                            method the way of collecting data should be followed as shown in the
                            calculated example. It is acceptable to estimate securing angles, to
                            take average angles for a set of lashings and similarly arrive at
                            reasonable figures of the levers a, b and c for the balance of moments.
                                
It should be born in mind that
                            meeting or missing the balance calculation just by a tiny change of one
                            or the other parameter indicates to be near the goal anyway. There is no
                            clear-but borderline between safety and non-safety. It in doubt, the
                            arrangement should be improved.