"September 1971." "15020 ENN 09/71." Includes bibliographical references (pages 37-38).

A reconnaissance study has been made to determine the extent of pollution which results from the operation of a two-cycle outboard engine. Comparisons have been made of engine operation with and without a pollution control device attached. Studies have also been made of the biodegradability of the fuel and exhaust products. Tests made in a swimming tank with an untuned engine have shown that the quantity of fuel wasted as exhaust varied from about 7 percent of the volume of fuel used at high speeds, to over 30 percent at low speeds. For a recently tuned engine, the quantity of fuel discharged ranged from about 3 percent at high speeds to about 26 percent at low speeds. When the Goggi pollution control device was installed, these quantities were intercepted and collected rather than discharged with the exhaust. Analyses at various depths indicated that nearly all products separated from the water in a short time and collected on the surface. Very little dissolved or emulsified oil was noted. Various analytical techniques were studied. Both fuel and exhaust products are capable of supporting microbial growth. Growth rates, however, appear to be limited by available oxygen.