This library holds the SimObjects for fishing gear and for autonomous underwater vehicles, in three groups. The nets and cables are not here: they come from fhsim_marine_elements (Net/NetStructure, Cable/LumpedMass, Cable/Branched), the water and the seafloor from fhsim_environment, and signal sources and the default vessel mesh from fhsim_base. Every SimObject has a page with its parameters, ports, units and defaults.

Trawl (Trawl): the parts of a trawl system that are not the net. Trawl/Vessel is a simple vessel with warp fastenings (WarpPos1 to WarpPos<NumWarps>). The doors (Trawl/TrawlDoor, the variants with an added foil, controlled lift or warp control) take the warp force in Force1 and the bridle forces in Force2 and Force3, and give their fastening positions and velocities in Pos1 to Pos3 and Vel1 to Vel3. A trawl is assembled in XML: vessel WarpPos to a warp cable, the warp's far end to Door.Pos1, the door's Force ports from the cables, and the bridle cables to the net. Trawl/CenterWeight is the clump of a double trawl, Trawl/Crowfoot a solver for the point where up to three lines meet, Trawl/PIDController and Trawl/Actuator build controllers, Trawl/TrawlGeometryController sets the warp lengths from the geometry, and Trawl/TrawlReporter and Trawl/ValuesDisplay report values as ports and on the HUD. Examples of a whole assembly are in data/trawl/demos (installed to playpen/examples/demos/fishery/trawl) and examples/input/Example.xml.
Seine (Seine): Danish seining. Seine/Operation gives the schedule (vessel heading and speed per phase, warp lengths, when the buoy is set), Seine/Vessel is the vessel that follows it and owns the net and warp attractors, Seine/Buoy switches a warp end between the buoy and the vessel, and Seine/Cable is a Cable/Branched whose nodes the attractors pull. examples/input/SeineOperation.xml and SeineCable.xml show the wiring.
AUV (Auv): Auv/Vehicle is a survey AUV with hull, fins, thruster and battery, Auv/UndulateDiveControl and Auv/UndulateMissionControl give its saw-tooth dive and waypoint guidance, and Auv/CTD, Auv/SilCam and Auv/Echosounder are the sensors it carries. The sections below describe the wiring, the wakes and the survey scenario.

The set of available SimObjects can be found in modules. Known review issues are listed in Review issues — fhsim_fishery. A settled steady tow of the morenot520 trawl, and why the net-hydrodynamics downstream check never settled, is in Steady tow of the morenot520 trawl.