During the first quarter of 2017, the TDD endured vigorous trials and tests at EON’s ‘Scroby Sands Offshore Wind farm’ together with vessel owners / operators Iceni Marine Services. The device was installed to vessel ‘Iceni Courage’ (South Cat 15 meter) by vessel builders ‘Alicat Workboats’, integrated and powered by hydraulic specialists ‘Hercules Hydraulics’ in Great Yarmouth, UK.
By the end of stage trials, the TDD outperformed expectations from all parties involved. A wave rider buoy issued by the OWA was deployed to provide accurate feedback and was followed by a thorough trials program carried out by Carbon Trust members. Results from the OWA trials demonstrated that the TDD could hold its pivoting jaws with negligible vertical movement in wave heights of up to 2.7 meters. Sea states included seas from ahead, astern and a beam. This achievement was deemed ‘outstanding’ by OWA partners which reinforces the team’s belief that an innovative access / transfer system can improve and conduct safer transfers at sea, even in challenging conditions with wave heights of up to 2.7 meters with a CTV as little as 15 meters in length.
We believe the TDD will change the future of offshore transfers…
Although the primary goal was to create a system which would enable transfers in more adverse conditions on Offshore Windfarms, it goes without saying that the key feature of the TDD is its ability to substantially increase safety in all aspects of transfers offshore… Be it from a Crew Transfer Vessel to an offshore structure (windfarm, Sub Stations, Platforms), a small Cargo vessel or Safety Boat aiding Oil and GAS Rigs, a Pilot Vessel transferring a Pilot to a Ship or even being used as an additional feature utilizing a light weight device to aid compensated gangways (Walk2Work).
This mobile, compact, easily maintained system can improve all aspects of transfers conducted at sea with minimal change from current methods to be adapted.
INCREASING WORKABLE WEATHER WINDOWS
That said, it has proved to withstand adverse sea conditions, enabling a stable platform on a 15meter vessel in seas of up to 2.7meters.
This is a huge accomplishment and increase to the current 1.2 – 1.5meter max wave height enforced by most offshore windfarm sites for similar size vessels.
This will undoubtedly afford greater access and workable weather windows, resulting in increased productivity and reduced losses caused by failed transfers in conditions where conventional access fender methods are not viable.
OFFSHORE INDUSTRIES WE CAN IMPROVE
CREW TRANSFER VESSELS
THE TDD WILL CREATE A MORE STABLE PLATFORM BETWEEN CTV’S AND OFFSHORE STRUCTURES IN ADVERSE SEA STATES, ALLOWING FOR SAFER TRANSFERS AND INCREASED WORKING WEATHER CAPABILITIES.
FOLLOWING THE RECENT BREAKTHROUGH OF WINDFARMS BUILDING SCHEMES WITHOUT FINANCIAL AID, THE ABILITY TO INCREASE WEATHER WINDOWS SAFELY WILL PROVE INVALUABLE TO THE COMPETITIVE AND INCREASING GLOBAL GROWTH OF THE OFFSHORE INDUSTRY.
SERVICE OPERATIONS VESSELS DAUGHTER CRAFT
AN ULTRA-LIGHT WEIGHT TDD FITTED TO SOV’s DAUGHTER CRAFT WOULD PARTICULARLY BENEFIT THE ‘ROUND 3’ OFFSHORE WINDFARMS BEING PROPOSED AS THE NEXT GENERATION OF OFFSHORE WINDFARMS, ALONG WITH OTHER MOTHERSHIP-DAUGHTER CRAFT INDUSTRIES SUCH AS OIL & GAS OR OFFSHORE RESCUES.
WALK TO WORK
COMBINED WITH CURRENT MOTION COMPENSATED GANGWAYS THE TDD COULD FURTHER IMPROVE THE CONNECTION AND FAIL SAFE GRIPPING TO OFFSHORE STRUCTURES, PERMITTING THE GANTRY TO DOCK DIRECTLY TO ANY PART OF CONSTRUCTION SECURELY WITHOUT MECHANICAL ENTANGLEMENT.
PILOT BOAT TRANSFERS
THE TDD COULD PROVE ESSENTIAL TO IMPROVING THE SAFETY FACTORS INVOLVED WITH PILOT TRANSFERS, PERMITTING THE SMALLER VESSEL TO TAKE UP A SECURE AND STABLE DOCKING POSITION ONTO A DESIGNATED CYLINDER RIGGED A-BEAM OR ASTERN OF THE SHIP DURING THESE TRANSFERS.
AT PRESENT, PILOT VESSELS ARE FORCED TO RELY SOLELY ON THE VESSELS RUBBING STRAKE TO BOTH PROTECT THE VESSEL’S HULLS AND CREATE GRIP, LEAVING THE VESSEL UNABLE TO ‘DOCK’ AND THEREFORE ENABLING THE DANGER OF A GAP EMERGING BETWEEN VESSELS DURING TRANSFERS.
OIL AND GAS
INSTALLING THE TDD TO A SAFETY BOAT SUPPORTING OIL AND GAS RIGS COULD REDUCE (BUT NOT ELIMINATE) THE NEED FOR EXPENSIVE HELICOPTER TRANSFERS, DUE TO THE INCREASED SAFETY IN ADVERSE WEATHER MARGIN.
USED AS A FRONT MOUNTED TOW HITCH THE TDD WOULD PROVIDE A GREATER PURCHASE ON THE BARGE AFFORDING IMPROVED DIRECTIONAL CONTROL, USEFUL UNDER VOYAGE AND AT A TIME OF MANOEUVRING IN RESTRICTED PORT AREAS.
USED AS A FRONT MOUNTED TOW HITCH THE PROPELLING VESSEL WILL HAVE A GREATER PURCHASE AFFORDING IMPROVED DIRECTIONAL CONTROL AND OVERALL MANOEUVRABILITY, THUS ALSO ERASING THE REQUIREMENT TO USE WARPS OR TOWING BRIDLES WHICH REQUIRE CONSIDERABLE OBSTACLE FREE ZONES TO PERMIT THE RELEVANT TOW TURNING CIRCLES.
HOW IT WORKS
The TDD goes through a primary phase where the jaws take the shape of the cylindrical fender tube. This is shortly followed by a secondary phase known as “thrust-out”. A combined dampened stroke of 750cm enabled by hydraulic rams and accumulators.
The TDD can deploy on to a tube whilst the vessel is simultaneously in a roll, pitch and off centre whilst addressing all 6 motions of freedom – heave, pitch, roll, yaw, sway and surge. Conversely, due to mechanical advantage a vessel can obtain a higher level of grip with a proportionally reduced amount of propulsion, thus minimizing pushing force required to maintain a stable platform against offshore structures.
An additional (but optional) hydraulic assistance mode can be implemented, which operates in a similar mode to applying a brake pedal of a car. This optional ability to add clamping will also allow substitution or minimal propulsion, enabling transfers to light anchored structures such as floating LiDAR’s, anchored barges or jack-up vessels. This optional ability, whilst using little or no propulsion, also enables transfers in adverse weather conditions to ships under DP (where CTV’s / WFSV’s are instructed to push on with minimal propulsion as it can upset the mathematical model of the DP vessel).
Another key feature of the system is the ability to alter the lateral position without disengagement. This can be achieved by simply reducing forward propulsion and re-applying when at the desired height, enabling clamping with its RG Seasight-Fenders.
Concept Trials Footage
The priority throughout the development process has been to make the TDD fail-safe, ensuring that the risk of mechanical entanglement to any offshore structure is completely mitigated. This is achieved by making the amount of grip applied to the offshore structure relative to the propulsion applied not protruding 180 degrees of the receiving cylindrical tube. The key features required from the design and model testing work were to create a simple and lightweight device which can effectively stabilize, pin and grip the transfer position. Offshore Transfer Devices and Hercules Hydraulics have created a cushioned approach which will minimize impact loads and offer protection to the device, vessel and offshore structures in greater wave height conditions. In addition, this will aid fuel economy, as well as wear and tear to vessels engaged in prolonged transfer operations with personnel or equipment.
INVEST IN THE FUTURE OF
SAFE TRANSFERS AT SEA…
Together with it’s contractors, Offshore Transfer Devices have now proven that the Tube Docking Device (TDD) can change the way offshore transfers are conducted. We are now looking to partner with an established marine engineering firm who can provide further expertise, venture capital, and assistance in gaining global market exposure.
+44 (0) 1492 874908
+44 (0) 7957 448346
1 Vaughan House
23 Vaughan Street