1Weather windows. Example: Towing of module across North Sea.

ProblemThe barge can not widthstand Hs>5m in beam seasThis may occur if the barge is in free drift, I.e. towline breaks and Hs > 5m..

Main dataDuration of tow 60 hoursStart: If weather forecast on Hs < 3m is at least 48 hours

QuestionWhat is the probability of failure?

Approacha. and b. are 100% correlated.Find the probability of Hs>5m if the forecast says Hs

2Wave statistics - scatter diagram

1 1 : 2 2: 3 03:04 04:05 05:06 06:07 07:08 08:09 09:10 10:11 11:12 12:13 13:14 14:15 15:16 16:17 17

0.5 7 18 5 2 32 321 215 691 376 77 6 1 1366 1398

1.5 82 1380 1161 354 67 3 1 3048 44462 13 797 1502 739 217 25 1 3294 7740

2.5 176 1314 826 287 66 8 2677 104173 1 22 734 851 359 77 25 4 2 1 2076 12493

3.5 11 244 873 381 133 34 8 2 1686 141794 6 76 669 481 162 50 7 1 1 1 1454 15633

4.5 2 22 350 440 159 47 3 3 1026 166595 1 10 104 400 161 44 9 1 1 731 17390

5.5 4 38 292 163 43 10 3 553 179436 1 14 149 169 60 17 5 415 18358

6.5 3 59 178 33 14 1 288 186467 28 130 42 10 210 18856

7.5 17 69 62 6 1 155 190118 47 60 6 113 19124

8.5 19 63 7 89 192139 9 43 8 3 63 19276

9.5 2 31 10 1 44 1932010 6 12 2 20 19340

10.5 2 16 18 1935811 1 11 2 14 19372

11.5 1 4 5 1937712 1 1 19378

12.5 1 2 3 1938113 1 1 19382

13.5 0 1938214 1 1 19383

14.5 0 1938315 0 1938315 0 19383

0 193830 193830 19383

0 0 0 318 3104 5449 4900 3184 1573 657 164 30 3 1 0 0 0 0 19383 5607850.0 0.000 0.000 1.641 16.01

428.11

225.28

016.42

78.115 3.390 0.846 0.155 0.015 0.005 0.000 0.000 0.000 0.000 100.0

0 0.00 0.00 1.64 17.65 45.77 71.05 87.47 95.59 98.98 99.82 99.98 99.99 100.00

100.00

100.00

100.00

100.00

200 200

Zero crossing periodS

i

g

n

i

f

i

c

a

n

t

w

a

v

e

h

e

i

g

h

t

3Wave statistics. Cumulative probability of significant wave height P(Hm0)

One year extreme: 10.7 m10 year extreme : 12.7 m100 year extreme : 14.6 m

447

24

Pipeline repair, large water depthInspection Large monohull Large semisubInstall welding habitat Large monohull Large semisub

34

Large crane vesselMooringPiling

54

3.5

Drill ship (head seas)DrillingRunning casingBOP and riser handling

3

1072

42

1.5

SemisubmersibleDrillingRunning casingBOP and riser handlingMooring

Significantwave height