Mooring Loads Due to Parallel Passing Ships - State Lands ...

EVALUATION OF PREDICTIVE METHODS
The two existing methods of predicting mooring loads due to passing vessels
are now evaluated. These include the empirical equations of Flory (2002) and the
empirical corrections to the deep-water theory of Wang used in the PASS-MOOR
spreadsheet by Seelig et al. (2002). As noted, both methods are based on scale model
tests data of Remery which used models of large oil tankers.
Flory Method
Flory gives the peak loads in the following form:
[ 0171 . 0134 . ln( ∆ ) { 071 . 028 . ln( ∆ ) } ln( − 006 . ) ]
(. ∆ − R ) { 441 . 193 . ln( ∆ ) } ln( )
( − . ∆ R + ) { 1719 . 514 . ln( ∆ ) } ln( − 0. 06)
2
X X F R R R
F = C S V + − +
S
[ ]
[ ]
2 1168 2.25
Y Y F R R
F = C S V e − +
S
2 0 47 2.651
M M R R
M = C S V e − +
S
where ∆R is the displacement ratio as defined earlier (displacement of passing ship
relative to displacement of moored ship) and where SR is the beam-to-beam separation
ratio given by SR = (S-(Bp/2)-(Bm/2))/L where Bp and Bm are the beams of the passing
and moored vessels respectively. The coefficients CX, CY, and CM are used to
represent the effects of underkeel clearance as
0. 0955−0. 6367 UKCR
CX= e
05157 . −3438
. UKCR
CY+ = e
0343 . −2288
. UKCR
CM−= e
UKCR = Underkeel Clearance Ratio =
d − D
The coefficients SF and SM are scale factors used to convert from model to full
scale and are given by
S = 15 .x10
L
where
L is the length of the moored ship in meters.
NFESC TR-6056-OCN
F
−5
SM
= 59 10 9
x L
−
26
D
(5)
(6)
(7)