OOPS ! sorry about old info...I`m really an aeromodeller
. Some of the "smoke" one sees on model boats is pretty poor, mere whisps. What about laying down a smoke-screen with thick black smoke? Pyrotechnics must be the only way to get this. Rescue emergency smoke is great but only in bright orange (also very expensive if not used for saving your life). Plumbers drain test pellets are OK but brief, about 90seconds, and stink of celluloid. My boat only needs the smell of kerosene (gas turbine) with a little smoke only at start-up.