These measurements allowed the ship's officers to estimate more accurately the projected clearance, taking into account draught and tide.

Another BMT subsidiary, BMT Cordah Ltd, has been in the news with the launch of a new subsea acoustic information system which will help assess the impact of underwater noise on marine species. ISAAC is the culmination of a two year research and development project and has been designed for intuitive use by specialists and non-experts alike.

Underwater noise can originate from many different offshore operations, including oil and gas exploration, pipeline laying, dredging, hydrographic survey equipment, and wind farms.

Recent evidence suggests noise can adversely affect marine mammal populations by disrupting normal feeding and breeding behaviour.

ISAAC uses a Gaussian ray tracing approach to determine the way acoustic ray paths travel between source and target position, including those reflected from the sea surface and sea bed. The ray paths may refract with changes in water density, salinity, temperature and sea bed type. Users of the system are able to determine the spatial extent of noise propagation and whether noise generated from subsea activities exceeds sensitivity levels for various species such as whales and dolphins.

MJ Information No: 19927