TMR4225 Marine Operations, 2007.02.01

1. TMR4225 Marine Operations, 2007.02.01 JAMSTEC website: http://www.jamstec.go.jp/jamstec-e/ships.html

2. Some JAMSTEC vehicles

3. TMR4225 Marine Operations, 2007.02.01 • Lecture content: • ROV types • Rov operations • Hydrodynamics of ROVs • Simulation as a tool for operational validation • ROV pilot training

4. ROV overview • ROV: • Remotely Operated Vehicle with umbilical connection to mother vessel • Umbilical is used for power transfer to the vehicle and for communication between it and its pilot • Important working tool for subsea installations and maintenance • Increasing depth rating – systems designed for operation down to 2500 – 3000 m • Umbilical handling is critical for most ROV operations

5. ROV types/classes • A common classification is: • Low cost observation ROV (electric) • Small observation ROV (electric) • Large observation/light work ROV (electric) • Ultra-deep observation/sampling ROV (electric) • Medium light/medium work ROV (electro/hydraulic) • Large heavy work/large payload ROV (electro/hydraulic) • Ultra-deep heavy work/large payload ROV (electro/hydraulic)

6. Hydro Products RCV 225 on sea trials for Taylor Diving, 1976

7. This 1980 photo of a Diver handing a wrench to an RCV 150 while an RCV 225 observes is a perfect illustration of the "passing of the baton" from man to machine

8. Deep Ocean Engineering Phantom 300 Under-ice Dive

9. Canyon's Quest ROV being recovered off Hawaii in 2003

10. Oceaneering Magnum, used most often in drilling support

11. Subsea 7 – Hercules rated for 2000 m waterdepth

12. Perry Trenching system

13. From MTS ROV site, 2004 estimates

14. Examples of ROVs • Check organisational web sites • http://www.rov.org • http://www.rov.net • http://www.rovworld.com • http://www.diveweb.com/rovs/features/uv-wi99.01.htm • Check suppliers and operators websites: • http://www.kystdesign.no • http://www.sperre-as.com • http://www.oceaneering.com • http://www.stoltoffshore.com

15. NTNU ROV Minerva • NTNU has bought an ROV for biological research • 2 Dr. ing studies have been allocated to develop tools and procedures for scientific use of the ROV • For more info see the web site: • http://www.ivt.ntnu.no/imt/minerva

16. Minerva ROV

18. ROV deployment

19. ROV operational goals • Visual inspection • Inspection of underwater structures • Observation of ongoing work tasks on subsea structures • Biological observation • Different types of mechanical inspection • Non destructive testing • Mechanical work • Biological sampling, water column and bottom

20. Flow characteristics for standard operations • ROV • Non-streamlined body • Mostly turbulent flow due to separation on edges • Low speed • Large angles of attack; have to be able to operate in cross current • Different characteristics for up and down motion • Complex flow due to interacting thrusters • Umbilical drag can be high for operations at large depths • Tether management system can be used to remove umbilical induced motion of ROV

21. ROV umbilicals • Vessel motion and indusced motion at the upper end of the umbilical • Umbilical geometry resulting from depth varying current • Use of buoyancy and weight elements to obtain a S-form to reduce umbilical forces on the ROV • Induced transverse vibrations of umbilical • Forces and motions at lower end of umbilical

22. Equation of motion for ROVs • 6 degree of freedom (6DOF) model • No defined steady state motion as a baseline for development of motion equations • ROVs are usually asymmetrical up-down and fore-aft • As far as possible the ROVs are designed for port-starboard symmetry • See section 4.6 of lecture note for ROV motion equation

23. Hydrodynamic added mass/moment of inertia • 6 x 6 matrix • Non-diagonal terms exists • Terms may have different values for positive and negative accelerations, especially for heave and pitch motion • Ideal fluid sink-source methods can be used • Motion decay tests can be used to find some terms • Generalized Planar Motion Mechanism tests can be used to find all terms • Simplified 2D crossections can be used to estimate some of the terms

24. Velocity dependent forces (drag and lift) • Non linear terms are important • Streamlining of bouyancy elements influence both drag and lift forces and moments • Motion decay tests can be used to find some drag terms • Generalized Planar Motion Mechanism tests can be used to find all terms

25. Minerva ROV

26. MINERVA tests • Drag tests, varying speed • Drag test, varying angle of attack • Full scale tests • Use of vehicle to generate input to parametric identification of mathematical model characteristics • Exercise no. 4 includes comparison of own calculations with model test results for MINERVA

27. Minerva 1:5 scale model test

28. Minerva 1:5 scale model test

29. Other forces • Gravity and buoyancy forces and moments • Thruster forces and moments • Control forces from any additional control units • Umbilical forces • Environmental forces • Interaction forces from bottom and/or sea bed structures

30. Summary ROV • Observation platform to support topside operators performing complex subsea work tasks • Workhorse for installation and maintenance tasks • Tether management system is a must for ”workhorse” ROVs