## 2 Development of the Profiler  
### Design  
The development focused on the profiler layout of the self-sufficient winch-type tethered device, where the motor drive, controller, and battery pack are placed in pressure-proof cylinder housing. The other end of the winch wire was secured to the bottom anchor or subsurface buoyancy. Originally, the positive buoyant profiler was designed to operate in an upright position. Hence, environmental sensors and positioning communication antennas were mounted on the upper-end cap of the profiler housing, as in an Argo ocean float, whereas the winch spool was located in the lower part of the profiler hull (Figure 2). Upon moving to a predefined parking depth controlled by a pressure sensor, the motor drive rotation was reversed, changing the direction of winding/unwinding. By winding and unwinding the spool wire, the profiler moved up and down in the water to measure the depth of the aquatic parameters using environmental sensors. For another application with regard to under-ice operations, the profiler was assumed to be negative in terms of the buoyancy and had to be turned upside down to hang down from the surface ice with the sensors facing downward. The near-surface horizontal flow generates a hydrodynamic drag on the profiler. The hydrodynamic drag force is proportional to the square of the flow speed and the cross-sectional area of the profiler. In the absence of surface waves, a tethered profiler connected to the bottom anchor using a synthetic low-stretch wire drifts with the flow, while the wire is tensioned. At a high flow velocity, when the flow around the profiler becomes turbulent, the positive buoyant profiler may not reach the surface or can quickly be pulled back under the water after surfacing owing to the hydrodynamic drag and wire tension force. Field trials exhibited that the profiler in the upright position becomes unstable at the sea surface and submerges owing to the current, which has a high rate of 0.3 to 0.4 m/s. The hydrodynamic drag force can be reduced by maintaining the horizontal position of the profiler in the water flow, such that the longitudinal axis of the profiler cylindrical hull is parallel to the oncoming flow. Therefore, we have redesigned the profiler to comply  
Figure 2: Prototype of the automated tethered profiler (**left**). The prototype profiler pierces the sea surface (**right**). The orange collar is the stabilizing disk. RBRconcerto C.T.D++ is mounted at the upper-end cup. with the aforementioned requirements. This profiler is known as Winchi (Figure 3). A suspension bar is designed to maintain the horizontal position of the profiler. Additionally, the profiler is balanced. A polyethylene suspension bar is attached to the profiler hull using two claps. There are two outrigger floats, which are fixed at the structural portions of the clamps to generate buoyancy and lift the GPS and GNSS communication antennas out of the water, thereby mitigating the effect of the waves while the profiler is surfaced. The main hull and two outriggers include the open trimaran platform of the profiler. For the profiler cylindrical hull in the horizontal position, the winch is located at the rear part of the profiler. The Dyneema(r) synthetic low-stretch wire (Figure 4) connects the spool around the bypass rollers at the tail of the suspension bar and the roller below the cylindrical hull located at a distance of approximately 1/3 of the length of the hull (Figure 5). There are vertical keels and horizontal stabilizers at the tail that contribute to the longitudinal and directional stabilization and control of the profiler in the flow. The hydrodynamic lift force acting on the horizontal stabilizer helps maintain the horizontal position of the profiler. Figure 4: Back view of the profiler wet compartment that houses the winch. The winch wire passes through hawsehole of the wet compartment. Figure 3: Automated tethered profiler—Winchi—with the suspension bar; GPS/GSM module; and conductivity, temperature, and depth probe RBRconcerto C.T.D++.