OCIMF_Mooring_Equipment_Guidelines_(Second_Edition)

(e) Spring line requirement by use of formulae (24):

S x MBL =

1.992 )( 20.6 )( 39.6 - 0.0398 )( 234 x 39.6 + 19.9 x 39.6 + 40 + 0.369(0.01 )( 2341 + 234)

= 1625 - 368.8 + 788 + 4{) + 288.4

= 2373 kN

with S = 4

2373

MBL = --. = 593 kN (= 60 tonnes force)

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(f) Breast line requirement by use of formula (25):

BR x MBL = 23411.550(20.6 - 14.0) + 1.291 )( 14 + 2.0664] + 5J7

= 7624 kN

with BR = 8

7624

MBL = --= 953 kN (= 97 tonnes force)

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(g) Actual uncs provided:

Since the wind area for t.bis sltip is known, the more accurate formulae (22) and (23) should

be used iD calculating line requirements. (The example ship has a forecastle and poop

with a larger wind area Ihan the statisrical average]. Also, as recommended, all lines are

of the same size and material. This ship is therefore provided with a total of 12 lines

(four spring lines, eight breast lines) of 40 mm diameter wire rope with independent wire

core, each having a rrunimum breaking strengtb of 1008 kN (:: 103 tonnes force).

For a 75.000mJ gas carrier (prismatic tanks)

(a) Ship paniculars:

Lw = 220.0 m

D = 22.4 m

T = 8.0m (average ballast draft)

AT = 1003 ml (al average ballast draft)

AL = 3844 m 1 (al average ballast draft)

(b) Maximum forces on the ship, by use of fonnulae (16). (17) and (18):

F, max = 559 + 75 = 634 kN

FYF ma.'( = 1272 + 408 1680 kN

Fy" max = 1488 + 437 1925 kN

(c) Spring tine requirements,. by use of formula (26):

S )( MBL = 2235 + 299 = 2534 kN

Assuming the sbip ha.s a total of four spring lines (S = 4), the minimum breaking strength

required for each line wlll be:

2534

MBL = -- = 634 kN (= 65 tonnes force)

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