Fay's spreading laws for a slick of volume V on water, with buoyancy contrast D = (rho_w - rho_o)/rho_w: gravity-inertial r = 1.14 (D g V t^2)^(1/4); gravity-viscous r = 1.45 (D g V^2 t^(3/2) / nu_w^(1/2))^(1/6). The smaller radius is used. Mean thickness h = V / (pi r^2). Drift follows about 3 % of wind speed plus the current.

Booms lose oil by entrainment when the normal current exceeds about 0.35 m/s (0.7 knots). Evaporation is a simple teaching estimate. Real spills also emulsify, disperse and break into patches. Educational only; no affiliation with any organisation.