Hydramotion has launched its new USB plug-and-play MudBug MB400 system for determining the navigable depth of shipping channels by measuring the density of fluid mud. The new version features a fully-integrated multifunctional transducer incorporating density, temperature and pressure (depth) sensors plus interface electronics. Measurements are output from the transducer as digital data, enabling direct connection to a PC or laptop on the surface. The whole system is fully portable and powered through its USB connection to the PC/laptop, which eliminates the need for a separate power supply. The MudBug measures density in the range 800 to 1600kg/m3 with an accuracy of +/-1% at depths up to 100m. The data is shown in both tabular and graphic form on the PC/laptop and can be exported to Microsoft Excel for further analysis. The 316 stainless steel sensor can withstand being towed through marine sediment, while the smooth open surface allows fluid to flow round it with minimal risk of solid material entrapment.