OCIMF_Mooring_Equipment_Guidelines_(Second_Edition)

For a 75,000 m' gas carrier:

S )( MBL == 2.228 AT + 0.170 TLop

BR )( MBL == 2.012 AL + 1.291 Tlop

For a 125,000 mJ gas carrier (spheri.cal tanks):

S )( MBL == 2.388 AT + 0.170 TLsp

BR )( MBl == 1.898 AL + 1.291 TLop

2.6.5 Example Calculations

The following examples show the application of the approximate formulae.

• For an oil tanker Dj 90 kDWT with segregated ballast tanks

(a) Ship particulars:

Lop == 234.0 m

B = 39.6 m

D = 20.6 m

d == 14.0 m

(26)

(27)

(28)

(29)

ATI' == 755 m^1 (at design draft d); ATo = 1044 m< (at balJast draft)

AL8 == 4200 m^2 (at 6.7 m draft = 0.02 Lop + 2m); ALF == 2492 m^1 (at design draft d)

(b) Maximum forces on the ship, by use of formulae (7), (8), (9), (13), (14) and (15)

FuB load:

F, max == 415 + 139 = 554 kN

FYF mll)( == 375 + 760 = 1135 kN

FYA max == 707 + 813 == 1520 kN

Ballast (IMO draft):

F, max 520 + 72 = 592 kN

FYF [!lax 1193 + 41 = 1234 kN

FYA ma)( 1340 + 41 = 1381 kN

(c) Spring line requirements, by use of formula (22):

S x MBL == 2080 + 288 == 2368 kN

Assuming the ship will have a total of four spring lines (5 == 4), the min.imum breaking

strength required for each line will be:

2368

MBL = -- == 592 kN (== 60 tonnes force)

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(d) Breast line requirements, using formula (23):

BR )( MBI. == 3678 + 4229 == 7C)07 kN

Assuming that the ship has a total of eight breast lines (B == 8) symme1rically arranged

(four forward and four aft), the minimum breaking strength required for each line will be:

7907

MBL == == 988 kN (= 101 tonnes force)

8