Okay, last post to hopefully let you know where I come from and actually data used to formulate that. All data and quoted material is from the Kenai Watershed Forum Non-point Source Pollution Monitoring – Hydrocarbon Fact Sheet.
First quote: “Some agency partners have pointed to source of pollution in the inefficiency of 2-stroke engines. During operation, both the intake and exhaust ports are open at the same time, this allows fuel to pass directly through the engine. As much as 25% of the consumed fuel passes directly to the air or water, releasing toxic and carcinogenic materials, such as hydrocarbons to the environment”
I think we all pretty much knew that about the old 2-strokes, although I was somewhat surprised that it was as much as 25% raw fuel passed through.
Second quote: “Following this potential source, and at the request of the National Marine Fisheries Service, KWF conducted reconnaissance work in an attempt to determine the ratio of 2-strokes engines to 4-stroke engines in use on the river during the month of July and Early August. Based on 775 observations, we found 34%of the motors were 2-stroke, and 66% 4-stroke. However, we also noted that there are distinct and dramatic differences within specific user group populations. Our data indicated that more than 90% of guided motor boats were using 4-stroke engines compared to less than 50% of private boaters using 4-stroke.
Taking 34% from a total of 500 boats on the river during a peak use day (170 two-strokes), and estimate of 10 gallons of daily fuel consumption per boat, it is reasonable to assume that 400 to 500 gallons/day of raw fuel could be entering the river from this motor type.”
Yes, guides are running 4-strokes, we all know that, mainly because they are more fuel efficient and very quiet on the water. The non-guide 2-strokes are a significant source of raw fuel. 34% of the motors on the river being 2-strokes is significant. The information did not give an amount of hydrocarbon put in by four stroke engines. I know they presented some information to one of the groups on the Peninsula and stated that carbureted 4-strokes put in about a cup of fuel per 10 gallons while fuel injected 4-strokes were at least half that. 2-strokes were stated to put in 2 to 3 gallons of fuel per 10 gallons.
Also, Kenai Watershed Forum has stated that on peak use days there was an estimated 600 gal/day of raw fuel being put into the Kenai. They also state that 2-strokes put in 400-500 gallons of that. It is illogical not to start there when trying to reduce Hydrocarbons.
Marcus you stated on a post something about taking the mom and pop fishermen that use the river 2 or 3 times a year with a 2-stroke. Granted a guide that fishes day in and day out will put in more HC in motor to motor pure hourly over a season comparison but if you add up the 2 or 3 time a year user with a 2-stroke it becomes a significant amount of HC. 170 boats with 2-strokes out of a total of 500 boats is a lot of HC by the 170 two strokes. One could also argue that per river user (clients) guides attribute the least amount of HC per river user.
This is the data from which I have formed my 2-stroke vs. 4-stroke position. Could I live with no 2-strokes in July and allowed the rest of the year, “Yes”. Or maybe not….
Third quote: However the highest values do not exist in July as our grab samples may suggest, but rather in May, when very low boat traffic is present.
May is a pretty high run-off month with low flows, accounting for what appears to be a lot of HC. The Kenai Watershed Forum did not elaborate on this statement but I find it very interesting. I wouldn’t necessarily attribute the high level to 4-strokes or 2-strokes.