Wide swath bathymetry and imagery systems some users observations and thoughts

The new wide swath multibeams such as those used by the French Hydrographic Service (SHOM) and the French Institute IFREMER on vessels l´Esperance and l´Atalante respectively may be used even in rough seas. However the quality of bathymetry and imagery not only depends on accuracy and resolution of the multibeam itself but also on the correct coverage of the surveyed area. Due to the very wide swath which is now achieved, up to 150°, the effect of yaw and pitch movements may cause non uniform data location thus creating undersampled areas when transmit beams are not stabilized. Various data set have been analyzed to produce real examples of data spreading due to real ship´s yaw and pitch movements according to different multibeam options. The results are rather clear and imply that steered beams at transmit is a good improvement to cope with ships movements effects. However a good trade-off is to be selected with care to get full benefit of the multibeam technique, i.e. low cost of operation together with high quality standards