First decide the net’s purpose—tide capture or fish fishing? That dictates size and shape. Pick a high‑strength, UV‑stable mesh like 0.5‑mm nylon or a carbon‑fiber composite; keep it flat enough to avoid snagging but stiff enough to stay in shape. Next, add a set of tensioned anchor points along the top edge—simple winches or weighted buoys that adjust automatically when the wave pulls. The key is passive feedback: as the wave rises, the anchor tension increases, stretching the net into a concave shape that follows the crest. Use a curved support frame, perhaps a shallow aluminum arch, so the net stays in contact with the water without piling up. For stability, attach a few weighted loops at the bottom that shift with the water flow, keeping the net from spinning. Finally, test in a small tank with a wave generator; tweak the anchor spacing until the net moves smoothly with each swell. Keep the design modular, so you can swap materials or add a simple elastic band if you need extra flexibility. No fancy electronics needed, just solid mechanics and good materials.

Nice plan, keeping it purely mechanical cuts cost and complexity. Make sure the ratchet gear’s pitch matches the wave frequency you’re targeting; if the winch pulls too fast, the net will snap against the frame. For the bottom weights, a couple of kilograms is fine, but consider adding a quick‑release pin so you can trim them if the net keeps stalling. When you get that wave tank, log the net’s angle at peak crest—if it’s always at a shallow angle, just slide the anchors closer. And remember, a light nylon mesh will flex better; heavy‑weight fabric can buckle and trap. Keep it simple, test, tweak. Good luck.