Bibby Tethra

Bibby Tethra is a semi-SWATH coastal survey vessel which was Launched in May 2011, the sister vessel to Bibby Athena she is capable of maximising stability and seakeeping ability in challenging conditions.

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 (DP Capable), dual propulsion systems and comfortable air conditioned accommodation for up to sixteen.  Although the vessel has been built to Bureau Veritas (BV) Class rules, Bibby Tethra operates 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. 

Advanced Hull Design

The vessel’s hull design is based upon the Small Waterplane Area Twin Hull (SWATH - 27.5m x 10.0m) 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.


The vessel provides efficient 24 hour operational capacity with up to sixteen personnel onboard, having a maximum duration of ten 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 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.

High-Specification Equipment

The vessel’s bridge is equipped to an exceptionally high standard with the very latest in navigation electronics, including a bespoke dynamic positioning system (DP Capable) certified by BV (AM/AT Standard). Motion referencing for both survey and DP operations is provided by a pair of iXBlue high precision motion reference units (MRU).  The very latest iXBlue 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.

Bibby Tethra's sister vessel, Bibby Athena, was launched in December 2014 and boasts the same layout with some subtle improvements.


BuilderSocarenam Boulogne, France
Length (LOA)27.50m
Working Displacement134 GT
Cruising Speed12 knots
Economical Speed10 knots
ClassLloyd's Register 100A1SSC Catamaran, G6
DP Type/ClassBV AM/AT – DP Class 1 Capable
Operating CodeMCA SCV Category 1 (150 miles from safe haven)
AccomodationEight twin cabins providing accommodation for a maximum of 16 people

Spec Sheet: Bibby Tethra