Netting
Drag goes with the square of speed and power with the cube. Half a knot more is not half a knot more fuel.
— kN
Hydrodynamic resistance at the towing speed
A flat-panel drag model: real netting flexes, the mesh opens and closes under load, and the drag coefficient itself varies with solidity and attack angle. Use it to compare twine and mesh choices rather than to size a winch, and validate against measured warp tension.
Fishing Net Solidity & Towing Drag Calculator — free, with the formula and a worked example, at Textile School.