WP 6Exchange of dynamic predictorTwo ships operation, Tug and ship

Peter Grundevik, SSPA Sweden AB

Background

• Sometimes tricky to foresee future ship positions as a result of change in rudder turn or steam

• Conventional predictor – SOG, COG, ROT -- prediction of coming

ship positions

• SSPA Dynamic Predictor– SOG, COG, ROT, depth, draught, trim,

wind, rudder angle, propeller pitch/rpm, hydrodynamic ship model -- prediction of precise ship movements

Background

• Dynamic predictor - installed on-board Stena Line Ferries. Very positive attitude among the users

• EfficienSea project - Investigation & testing of an operational service offering exchange of dynamic predictor positions between nearby ships

• Conclusion - exchange of predicted positions– too much information. Not the intended course– not very useful for collision avoidance

• However - Dynamic predictor– useful on board own ship – precise manoeuvring in ports

Aims in ACCSEAS

• Is predictor exchange useful in manoeuvring with tug assistance?• The vessels are manoeuvring the main ship together• The service is proposed to be used

– in the beginning of a voyage – in the end of a voyage– for planning minutes and seconds ahead (not strategic)

• Test such operational service

- Simulator testing- Measure important parameters• time period for the operation• speed when landing on berth• repeatability of the manoeuvre• safety margins

- Interviews with Pilots and Tug masters

Test method and evaluation

Dynamic Predictor simulator screen dump

Predictor in Ship EPD• The interface to the ship EPD

• A simple dead reckoning predictor is added to the ship EPD for comparison

• The hydrodynamic predictor is linked to the Ship EPD

The test ship

• A Small LNGC, single screw CPP• LOA 155 m, LPP 147 m• Beam 22,7 m• Draught 7,35 m• Displacement 18 543 m3

• Bow thruster disabled• 50 ton ASD tug

Test port and Conditions

• Port of Gothenburg quay 518• SW wind 10 m/s• No current

The Simulator environment

• View 330 degrees • Chart displays– Ship EPD – Open source SW– Realistic hydrodynamic ship model based on data from

SSPA’s model tests plus over 60 years of experience

Tests performed

Test 1 Today situation – no predictor usedTest 2 Simple dead reckoning predictor used tug

Test 3 Dynamic Predictor used and shared, no forces exchangedTest 4 Dynamic Predictor & forces exchanged, ideal forcesTest 5 Dynamic Predictor & forces exchanged, resulting forces

Results and conclusions

• The pilot operating the test ship considers the dynamic predictor with ideal or resulting forces to be an additional help

• The simple ded reckoning predictor is considered to be of less use• Tug masters expressed that the situation awareness was

improved by ROT and dynamic predictor information• No significant difference in time, safety margins, landing speed or

use of power can be concluded with certainty• A tendency can be found when introducing the dynamic

predictor: assistance in learning the ship behaviour

Further work

• More tests are needed to look for significant results• Tests on more complicated, larger vessels, like VLCC are

recommended

AIS based Risk evaluation – possible service

• Collecting a lot of historical AIS data sets a normal ship behaviour• Looking at real time AIS data and compare them with the stored

normal behaviour abnormal ship behaviour can be detected• Vessels that deviates from normal behavior may represent a risk

- can be identified• A system using the technique can help VTS operators to identify

ships sailing an unexpected route• Such a algorithm was tested using logged AIS data on known

accidents in Swedish waters

Normal behaviour video

Unexpected behaviour video

Conclusions

• Based on normal ship behaviour it is possible to automatically identify ships diverging from the normal behaviour and alert VTS operator or the Officer on watch

• The algorithm was tested using high quality AIS data from about 20 real grounding accidents. The system did warn in almost all cases, except some few very special occasions (not leading to groundings)

• The technique is developed further in MonaLisa 2 and the results are very promising