40 CFR §1700.33

1. (a)For the purposes of this section small boat engine wet exhaust discharges refers only to discharges from vessels that are less than 79 feet in length.
2. (b)Vessels generating small boat engine wet exhaust must be maintained in good operating order, well-tuned, and functioning according to manufacturer specifications, in order to decrease pollutant concentrations and volumes in small boat engine wet exhaust.
3. (c)To the greatest extent practicable, low sulfur or alternative fuels must be used to reduce the concentration of pollutants in discharges from small boat engine wet exhaust.
4. (d)To the greatest extent practicable, use four-stroke engines instead of two-stroke engines for vessels generating small boat engine wet exhaust.
5. (e)Vessels using two-stroke engines must use environmentally acceptable lubricants unless use of such lubricants is technologically infeasible. If technologically infeasible, the use and justification for the use of a non-environmentally acceptable lubricant must be recorded in the vessel recordkeeping documentation.