Bibby Tethra

Bibby Tethra is a newly built 27.5m x 10.0m semi-SWATH coastal survey vessel which entered service in May 2011.

The vessel provides a large and exceptionally stable working platform due to her advanced hull design and ultra-quiet, extremely economical operating profile due to her diesel electric propulsion system. Tethra offers a range of unique features for a vessel of this size, including Dynamic Positioning (DP1), dual propulsion systems and comfortable air conditioned accommodation for up to sixteen.

The vessel’s hull design is based upon the Small Waterplane Area Twin Hull (SWATH) concept where the hull’s main buoyancy is maintained well below the water line. The area of the ship’s hull, both at and immediately above the water line is significantly reduced when compared to a conventional hull form, which means that passing waves have a significantly reduced effect on lifting the hull. This has a dramatic effect on minimising the vessel’s heave, pitch and roll motions and delivers a stability profile similar to that of a conventional mono-hull vessel over twice her size.

Although the vessel has been built to Bureau Veritas (BV) Class rules, Tethra will operate under Category 1 of the UK’s Maritime and Coastguard Agency (MCA) Small Commercial Vessel (SCV) code allowing her to work unrestricted out to 150 miles from a safe haven in UK waters. The vessel is fitted with a comprehensive range of safety, life-saving and communications equipment that surpass the requirements of current legislation. This includes items such as GMDSS VHF radio, MF/HF radio, SAT C GMDSS comms, satellite broadband and satellite TV.

The vessel provides efficient 24 hour operational capacity with up to sixteen personnel onboard, having a maximum duration of fourteen days. The accommodation is arranged into four en-suite twin cabins on the main deck and four twin cabins on the lower deck, two in each hull, with shared bathroom facilities. All accommodation areas within the vessel are air-conditioned with the bridge and survey laboratories benefitting from a dedicated cooling plant due to the large amount of window area.

The vessel’s bridge is equipped to an exceptionally high standard with the very latest in navigation electronics, including a bespoke dynamic positioning system (DP1) certified by BV (AM/AT Standard). Motion referencing for both survey and DP operations is provided by a pair of Ixsea high precision motion reference units (MRU). The very latest Ixsea HYDRINS inertial navigation system provides primary data for the survey sensors and a 4th generation Octans fibre optic gyro and MRU provides primary data to the DP processor. Both units act as secondary output / backup to each other and each carries IMO wheelmark approval.

The bridge also houses both the on-line and off-line survey laboratories and is configured with easy access to the rear upper deck and handling equipment with remote control of sonar winches and CCTV monitoring of all on deck activities. All data recording systems are housed in cooled and silenced 19” racking units which are protected by a series of uninterruptible power supplies (UPS). Multiple monitors at each work station allow data display to be configured to suit various applications. The main helm / operator station has direct communication with the survey room and survey navigation displays are repeated on the bridge.

Deck equipment includes a large hydraulic ‘A’ frame with 8 tonne safe working load, a 2m x 2m moon pool, an 18 tonne/m knuckle crane, container fixing points and twin sonar wells in each hull to enable through hull deployment of USBL and/or pinger subbottom profiler systems.

Permanent fit survey equipment comprises of a dual frequency, ultra high resolution RESON 7125 SV multi-beam echo sounder, C-Nav RTK GPS, Klein 3000 digital side scan sonar with dedicated high specification electro mechanical winch and Sonardyne USBL acoustic positioning system.

Builder	Socarenam Boulogne, France
Launched	2011
Length (LOA)	27.50m
Beam	10.00m
Draft	3.30m
Working Displacement	134 GT
Cruising Speed	12 knots
Economical Speed	10 knots
Class	Bureau Veritas - Special Service Oceanographic Research
Operating Code	MCA SCV Category 1 (150 miles from safe haven)
Accommodation	Eight twin cabins providing accommodation for a maximum of 16 people.