Isis Deployment TMS and Live Boating Inmartech08 Dave Turner Operations Co-ordinator
TMS Operations Why Why do do we we have have aa TMS? TMS? ItIt was was deemed deemed an an essential essential part part of of the the Isis Isis ROV ROV system, system, from from the the original project manager, who s background was from the N. Sea original project manager, who s background was from the N. Sea Oil Oil Industry. Industry. Trials Trials Cruise Cruise (James (James Clark Clark Ross Ross 169T, 169T, July July 2006) 2006) Our Our first first opportunity opportunity to to try try the the combined combined system. system. Location Location of of the the Hebrides, Hebrides, Scotland, Scotland, utilising utilising the the Inner Inner sheltered sheltered waters waters for for calm calm shallow shallow dives dives and and Outer Outer waters waters for for the the deeper deeper dives. dives. JCR Isis Layout James Clark Ross (JCR)
TMS Operations Dive 1 (112m water depth) Calm sea conditions. System deployed and recovered uneventfully. ROV decoupled and coupled several times from the TMS (minor problems with latch indicators). Seabed flying of the ROV with coordination of the TMS (approx 40m tether out). Generally a very successful dive. Attachment of TMS to ROV Stage 1 Stage 2
TMS Operations Dive 2 (2.324m water depth) Moderate sea conditions. The vehicle separated from the TMS on entry into the water. The decent of the coupled systems was very unstable. Due to the violent decent motion the systems were separated. Two bodied decent worked very well.
TMS Operations Dive 2 (2.324m water depth) Latching problems Heaving of the TMS prevented a smooth latching process. Mechanical latches proved to be unreliable. High risk of damage for a near surface latch (for two bodied ascent). Recovery The coupled system rolled excessively on the ascent. The coupled system was very unstable at the surface ( splash zone ). The recovery was difficult (trying to control peak loadings on the Umbilical).
TMS Operations Dive 2 (2.324m water depth)
TMS Operations Conclusions/Summary/Decisions Conclusion Due to deep water cable parameters. power limitations of the system (21kw). SWL 8000kg Vehicle underpowered. TMS winch underpowered. TMS is too light for the air surface interface (restricted for the cable parameters). Summary System unusable in its current state, unless flat calm conditions. Imminent science cruises (no time for development). More time consuming maintaining essentially two vehicles. Very successful trials with live boating. Decisions Possible future development into a two bodied system.
Deployment Launch Personal 4 x ROV Personnel (12hr watch). 1 x Winch/LARS Driver. 1 x Deck Coordinator. 1 x Pilot. 1 x Engineer. 2 x Deck Crew (for float attachment). Engineer Pilot Control Container Deck Coordinator Winch Driver
Deployment Launch Criteria Mid-ships Location. (less pitching, point of rotation, no streaming fwd required to clear props). Ship creates a lee from the weather. Ships main props secured. Ships tunnel thrusters reduced to 10% power. Deck Cameras situated to aid pilot (however, we insist that the pilot takes instructions from the deck coordinator).
Deployment ROV latched into (LARS) docking head. LARS being extended over the side of the ship. Slack Umbilical. Launch and Recovery System (LARS)
Deployment Creating slack umbilical for football float attachment. 2 x floats attached nearest to the vehicle (appox dist of freeboard + ROV clearance from the ship). Spacing of Floatation approx 8m. Total Floats x 8
Deployment First 2 Floats attached. Vehicle moving away from the ship, parallel to the A frame. The ship will assist in holding ROV position parallel. (removal of Surg or Sway from the DP). Floatation: Approx 8kg of buoyancy / float. Umbilical: Approx 8m = 8kg
Operations Subsea Delta Distance Monitoring of Umbilical. Creating a delta depth of 40m (generally for most operations). Delta = Cable out ROV Depth. Positioning From Ship USBL Navigation. Horizontal distance from ship (80 to 100m). Generally lead the ship with the ROV. Exceptions when running SM200 Survey. Aid carrying the wire. Reduce surging.
Recovery Floats removed as the vehicle reverses towards the ship. Ship assistance (sway, surg). Vehicle surfaces approx 60m away from the ship. Last USBL fix at 50m depth.
Recovery Isis lifted from the water. Good timing required. Alignment with the docking head. Nearly home. Isis latches firmly into docking head. LARS brings vehicle inboard. Vehicle lowered to the deck.
Summing Up Positives No operational restrictions encountered yet (except bad weather). Good manoeuvrability. Less maintenance than a two bodied system. Less spares, and storage space. Fast launch and recoveries. Fast turn around between dives. Successfully completed dives 94 (1,600 hrs) Negatives In rough weather the vehicle experiences pitching, but is manageable. No aerial view of ROV from TMS.