Here is a way to use a somewhat objective lens to compare the average fuel and engine load on the Niagara River caused by pleasure boats and the Whirlpool Jet Boats. 

Note that this spreadsheet only works in Internet Explorer v.5 or greater.

Instructions.

1. Estimate the numbers in the Yellow boxes.
2. The numbers in the white boxes are calculations.
3. If the total doesn't seem right, go back and change some of your estimates until you are satisfied that they are as accurate as you can get.
4. This is an ultimate "what if" based on your own estimates.

In the starting example, the red box indicates that the Whirlpool Jet Boats create an percentage increase (the % increase in the red box)  in environmental load due to burning fossil fuels in the Niagara River.

Rationale:

• I estimated the number of boats in each of the four Niagara River marinas.  The spreadsheet simply totals them
• The Whirlpool Jetboat's highest number is 16.  Are all 16 operating on the Niagara River?
• Most pleasure boats have one engine, a few have twin engines, but I'll average it at one.  All of the sailboats have one engine and many of the powerboats.
• I believe that the Jetboats built after the first 2, all have 3 engines at 500 hp each. 
• How many hours per week does the average pleasure boat run in the Niagara river.  Since more than 90% of the moving boats are sailboats who use their engines to move in and out of their docks and moorings, this is a light load.  Many pleasure boats don't go out every week.  An avid racing sailboat might go out for 2 races per week and one cruise, using their motor for perhaps an hour in total. 

Note that this does not factor into account:

• Gasoline vs. Diesel fuelled boats
• Different grades of diesel fuel.  Is Farm diesel worse than 'normal' diesel? What is being used?
• Law Enforcement boats.  We need them anyway, for sure!