Paul Moeyaert

Lloyd’s Register EMEA

Key contribution of Oceanographic research in providing an economic solution to Zeebrugge’s lack of hinterland connectivity

Paul Moeyaert


Wave measurement


Solutions:

• Noorderkanaal

• Dockships

• “extended” estuair regime


Access to the network of inland waterways from Zeebrugge:• Traditional inlandwater tankers

Provided “good’ weather

• CoastersBut too high requirementsAnd high investment/operational

costs

Due to lack of reliable knowledge of the risk-level


Extended Estuair

• Based on Risk analyses

• Simulation of ships motions and behaviour as a response to the 10years wave spectra: in the particular sea area


Statistical distribution of occurances of dangerous situations

• Slamming

• Greenseas

• Rolling

• Bending moment


Acceptable frequency

• Bending moment : once a life time

• Slamming: once per year

• Green seas : once per life time


Iterative process of designIf the number of incidents proves to be too

high : 2 possible actions:

•Restrict the allowable weather conditions

And/or

•Increase strength

Optimum solution


Relative vertical motion of point : fore, keel exceeding draft fore: number of exceedings per trajectory as a function of significant wave height in measured directional wave spectra Bol van Heist, Western Scheldt – Zeebrugge

1.0E-06

1.0E-05

1.0E-04

1.0E-03

1.0E-02

1.0E-01

1.0E+00

1.0E+01

1.0E+020 0.5 1 1.5 2 2.5 3

significant wave height (m)

num

ber o

f exc

eeda

nces

per

traj

ecto

ry (-

)

conditional minimumconditional maximumconditional averagecumulative average

SCHELDT-ZEEBRUGGE-SCHELDT

CARCARRIER - DRAFT 2.5 mMOTION POINTS 7-9 - SLAMMING

REF LEVEL KEEL

DIRECTIONAL SPECTRA BOL VAN HEIST 1998


Significant Wave Height

• Is a far more accurate criterion for reflecting the risks compared to the old yardstick : Beaufort Number

• As basis for designing ships

• But also as a criterium for the captain: whether to make the voyage or the wait for better circumstances


Further possible improvements

• Accuracy of predictions on medium term

• Directional predictions

• Distinction between:Swell

– Caused by remote storms – Long waves, traveling at known speed– well predictable

Local waves– Same predictability like the local wind– Shortcrested waves


0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 0.5 1 1.5 2 2.5 3wave frequency (rad/s)

side

ver

tical

am

plitu

de d

ue to

roll

/ wav

e am

plitu

de

(m/m

)

0 10 20

30 40 50

60 70 80

90 100 110

120 130 140

150 160 170

180

angle of incidence (deg)CARCARRIERDRAFT 2.50 m

Paul Moeyaert

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