The Sir William is Halcrow’s hydrographic survey boat. It was purpose-built for Halcrow in France, and delivered to the UK in September 2003. It is the only one of its kind in the UK.
The Sir William’s maiden voyage was a survey on the Clyde estuary in Glasgow. Other work includes a multi-beam swathe bathymetric survey of the water and riverbed around the Thames Barrier. It was the first time the area has been surveyed since the barrier was erected.
The boat is transported by trailer and is permanently mobilised. It’s suitable for use on coastal waters, inland waterways, lakes and reservoirs. Able to operate in shallow and deep water, it can carry out its work in water less than one metre deep or up to 20 nautical miles offshore.
Bathymetric data is collected using a multi-beam echo sounder, operating at 240 kilohertz. This measures the depth of the water across a wide swathe perpendicular to the boat, giving detailed information about the features on the bed below.
The data from each survey is produced digitally, including background mapping, reporting and photography. The information can be used to produce two and three-dimensional drawings, volume calculations, difference plots, cross-sections and fly-throughs.
