My First Field Work in Eight Weeks

The day starts early with quite an impressive sunrise over the hotel car park in Faenza giving me hope of a good day. The weather was reasonable but a bit foggy through the Po delta region on the 2 hour trek up to Chiogia. At the mob site the weather is clear and the seas calm, perhaps it will be a good day.


The vessel to be used for the survey is interesting. It is a modified sports boat where the cabin has been extended. There is a metal work superstructure which is for dual GPS antennas but also has an arm that swings out to act as a crane to help fit multi-beam echosounder to the side plate. This is it's first trip out since being fitted with a hull mounted SEA SWATHplus bathymetric sidescan sonar.
The sonar has been hull mounted to save on awkward bow mount deployments at sea. The mount is two thirds down the vessel and seems to work well. Transit speed to site was done at 15 to 18 knots and in theory you are ready to survey straight away. For this installation we did in fact use a bow mount with a SonarMite single beam echosounder and Valeport miniSVS fitted.

Being Italy and this being a very fast mobilisation and survey we had the inevitable 'spaghetti' wiring nightmare between all the equipment. The cabin is fairly compact in size so a single computer is used running both the swath software and the navigation programs, PDS2000 or QinSy, depending on the survey needs or hardware used. Both of these can run and acquire SWATHplus sonar data direct through a TCP/IP socket either on the same machine or over the ethernet. A Quad core machine was in use here with 4Gb RAM, so running swath and nav acquisition on the same machine is not an issue, although this takes away the flexibility of saving native SWATHplus raw file as disc contention will be an issue. An Applanix POS/MV , the cream of all motion sensors, was used for positioning and motion control and was feed with RTK CMR correction messages for accurate height control.

Transit to site was achieved in just under an hour, boring sea transit on calm seas with a slight swell. Moored up at an artificial island at the survey site and that is when the problems started, ranging from string decode problems (seems impossible to I/O test QinSy drivers that you build yourselves); too wiring problems. Frustrating couple of hours sorting out issues and finding best way forward to complete the survey aims, basically a fairly simple sidescan survey. Anyway proceed just using the swath software. Luckily the POS/MV calibration was complete in 3 minutes, the desk work establishing offsets and preparing a vessel config file paying off. The survey was complee in about 1.5 hours with some hairy moment close to a pipeline lay barge, or more strictly the anchor chain pattern. Having a hull mounted sidescan really works in these situations as we certainly would have lost a towed fish. Any way, managed to get back to dock with the last glimmer of the day and back to the hotel by 9pm. A 13 hour day and a qualified success, well we at least collected the data and learnt the lesson that even with preparation, something will jump out and bite you in the arse! The true essence of bathymetric blunering!