64 Show report | Oceanology International and allows the user to select which ones to ignore. One of the most important features of the PPK is the forward-backward processing, says Ollier. This processes GNSS data in the normal forward-time direction to calculate the receiver’s position. It then starts again at the end of the data-collection period and returns to the beginning to estimate the receiver’s position from the last observation back to the first. This step helps to detect and correct any biases or errors that may have accumulated during the forward processing. “Qinertia is a powerful and easy to use post-processing software that really improves the accuracy of your data,” he says. Lemvos, founded in 2022, presented its DockMaster automated docking and charging system for electric USVs up to 6 m long at the show. The company is also developing a family of USVs that are intended to operate unattended for up to six months at a time. “We wanted the ability to dock the vessel and undock it without having anyone physically there,” says Daniel Severinsen. “We looked around for docking systems that don’t need a person there, but there was really nothing on the market.” Severinsen describes the system as an electrically operated latch that is mounted to the front of the vessel, which latches itself to a pole on the dock to secure the USV mechanically. The system lets the boat roll, pitch and move vertically to cope with tides and waves, and withstands tensile loads up to 5 kN, he says. “That’s plenty for a USV up to around 6 m, depending on weather conditions.” Fitted to the bow of a monohull or on a bracket between the hulls on a catamaran, the latch is a slam-closed system, he says. “You drive the vessel in, and the latch slams shut and it’s secure, and then to release it you send a signal to an electrical actuator in the latch.” The dock itself is V-shaped to provide alignment guidance. Charging is by a low-voltage DC system that supplies current through the pole to a pair of copper contacts integrated into the latch. “The charger is quite smart,” says Severinsen. “It applies about 2-3 V continuously. Then, when it sees there’s a boat connected, it goes up to the full voltage to start charging, and the charging curve is programmable for the battery type and voltage. We can charge up to 3 kW on a 48 V system.” DockMaster development is complete and the system is entering production. Yellowscan showcased its new Navigator bathymetric Lidar, carried by a Clogworks Dark Matter hX Gen 2 heavylift hexacopter. Nassim Doukkali says the UAV equipped with the sensor can fly at up to 120 m above ground level and map the ground, the water surface and below the surface in shallow water in 3D. “One of the main purposes of the system is to map coastal areas where a boat cannot go with a sonar because of rocks or waves,” he says. Riverbed mapping is another key application, where water can be very shallow and the Lidar’s ability to penetrate vegetation is potentially very useful. “With our system, you can map up to two Secchi of water depth,” says Doukkali. This is a reference to a Secchi disk, which has alternating black and white quadrants, and is used to measure water turbidity. The Navigator Lidar’s green (532 nm) laser penetrates water to twice the depth at which a standard Secchi disc disappears as it is lowered in. In really clear water, the disc disappears at about 9 m. “It’s a Class 3B visible laser, so it could be dangerous for the eyes at up to 30 m,” he says. The Lidar operator is provided with safety glasses, and the team applies straightforward safety procedures June/July 2024 | Uncrewed Systems Technology GUI SBG System’s Qinertia 4 PPK software for surveyors, which minimises GNSS errors. The latest version features a new geodesy engine that processes GNSS data to generate accurate positions The latch mechanism with copper contacts for Lemvos DockMaster’s automated docking and charging system for USVs is designed for fixing to the prow of a monohull or between the hulls of a catamaran
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