Safetrans Safe design and operation of marine transports

Transcription

1 Safetrans Safe design and operation of marine transports

2 CONTENTS General Voyage Motion Climate Monte Carlo Simulations Calculation of Ship Motions Weather Databases User Group References 2

3 SAFETRANS Safetrans is an integrated tool to design marine heavy lift transports in a safe and efficient manner 3

4 TRANSPORT TYPES Self propelled vessel Towed transports Offshore operations 4

5 CALCULATION METHODS Design wave (calculation of ship motions) Voyage motion climate (scatter diagram method) Monte Carlo simulations (voyage simulations including captain s decision mimic) 5

6 RESULTS Voyage duration Long term distributions of weather conditions and ship motions Design values of wave height, motions and accelerations 6

7 VOYAGE MOTION CLIMATE Globe is divided in 2.5 x 2.5 deg. grid Each grid contains wave scatter diagrams for: 7 8 wave directions & 4 seasons Route is divided by legs which are determined by course changes or grid changes For each leg the statistics of the motions etc. are determined A statistical summation over all legs is performed, resulting in long term statistics of e.g. Mean speed & voyage duration Total number of oscillations Design values

8 MONTE CARLO SIMULATION Vessel finds its way to the destination under the influence of weather forecasts and ship capabilities in the prevailing sea conditions. Use of forecast database of wind and waves allows to simulate routing. Routing criteria are input. Weather &Forecasting Routing Criteria for tow & cargo Captain s Decision Mimic Decisions BRIDGE Vessel Operating Module Course & Power Ship course, speed & motion Data logging 8

9 MONTE CARLO SIMULATION General flow diagram voyage simulations: 9

10 MONTE CARLO SIMULATION Captain s decision mimic includes: Wait for weather Rerouting (incl. hurricane avoidance and safe ports/shores) Change course / reduce speed to ease motions Riding out a storm (survival mode) Shorten towline Reduce towline tension 10

11 INPUT OF VESSEL CHARACTERISTICS Hull lines, Loading condition, wind & current coefficients and resistance & propulsion 11

12 CALCULATION OF SHIP MOTIONS Automatic selection of calculation method: Strip theory calculation 2D linear theory Hull forms L/B 3 Normal transport ships, tugs Interpolation within Precal databases: 3D linear theory Hull forms L/B < 3 Rectangular and triangular hull shapes Import your own RAO database 12

13 RAO Roll [deg/m] CALCULATION OF SHIP MOTIONS Results presented as contour plots roll ampl. = wave freq [rad/s] 13

14 CALCULATION OF SHIP MOTIONS Roll damping & non-linearity: Viscous roll damping models: B/T < 6: Ikeda, Tanaka, Himeno B/T 6: Noble Denton method Roll non-linearity: The larger the roll angle / velocity the larger the roll damping. This results in lower roll peak values in the RAOs 14

15 WEATHER DATA 18 year wind and wave database including forecast data 41 year hurricane database Monthly averaged ocean currents Water depth 15

16 WEATHER DATA Hindcast/Forecast Database provided by Oceanweather Time series of wind and Hs, Tp and ϴmean for wind-sea and swell partitions x 1.25 global grid, almost 50,000 weather points at sea 18-year duration ( ) 12h time step, with forecast out to 7 days ahead 16

17 90 o W 90 o E 90 o W 90 o E WEATHER DATA Global grid from 70 S to 75 N 150 o W 180 o W 65 o N 150 o E 30 o W 0 o 30 o E 120 o W 70 o N 75 o N 120 o E 60 o W 60 o E 80 o N 85 o N 85 o S 80 o S 75 o S 60 o W 60 o E 120 o W 70 o S 65 o S 120 o E 60 o S 30 o W 0 o 30 o E 150 o W 55 o S 180 o W 150 o E 17

18 WEATHER DATA Tropical Cyclone Database: NOAA GTECCA dataset 41-year database from h time step Wind/wave fields estimated using Cooper (1978) model 18

19 SAFETRANS USER GROUP Participation to the user group allows you to: Steer developments Get updates and new releases Attend training sessions Meet colleagues User group meets twice a year 1998 JIP formed, 32 participants 2001 JIP closed, User Group formed 2016 User Group, 18 participants 19

20 SAFETRANS USER GROUP

21 REFERENCES Aalbers, A.B., et al, SafeTrans: A New Software System For Safer Rig Moves, City University Jack Up Conference, London Aalbers, A.B., Nataraja R. and Anink S., Design Criteria For Weather Routed Transport,, RINA Conference - Marine Heavy Transport & Lift I, London 2005 Vavasour, J., Devoy, D. and Mills, T., A New Approach To Designing And Approving Barge Tows, Marine Operations Specialty Symposium, Singapore 2008 Cooper, C. et al, Case Studies Of Ocean Transports Using The Safetrans Simulator, RINA Conference - Marine Heavy Transport & Lift II, London 2008 Grin, R. et al, Enhancements in Monte Carlo Simulation in SafeTrans 5, RINA Conference - Marine Heavy Transport & Lift III, London

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