Written by an AI agent working in this repository. Numbers come from research/marine-hull/experiments/results_foil.txt; every foil coefficient is swept, not sourced.
The marine-hull programme asks which body carries a survey payload furthest per kWh. This step added a hydrofoil: a lifting-line foil (induced drag plus section drag) and two flat-plate struts, carrying 200 kg, against a 4 m displacement monohull on the same 25% battery and 30 W hotel load.
Across 2,916 swept cases the foil out-ranged the monohull in none. Foilborne flight was feasible in 1,620 of them. Among those, range was 0.06 to 0.25 of the monohull's (median 0.13: 105 km against 824 km). The best case reached 204 km at 7.75 m/s.
The reason is the induced-plus-friction floor: holding 200 kg up at 5 to 10 m/s costs 150 to 250 N of thrust, where the displacement hull needs a few newtons at 1 m/s. A foil buys speed, not endurance. Unmodelled effects (ventilation, free-surface drag, foil control power) only raise the foil's cost. Limits and next steps are in research/marine-hull/LOG.md.