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Flotilla 11


Carbon Monoxide is present behind your boat too.

Do you TOW SKIERS, TUBERS, DISABLED BOATS?  Are your kids sitting in a towed DINGHY?:


Tests were conducted whereby a dinghy was being towed behind a speedboat with a 350CID engine. They mounted
test sniffers at 2 feet above the water line (people sitting in a towed boat that is disabled) and at 5 feet above the water- that could be the height of a Skier's nose.

Below are some of the results. Conclusions are at the bottom of the page.


dinghy being towed with measuring equipment on it


dinghy being towed


CO vs distance behind boat chart for different speeds


CO vs distance behind boat  Peak levels, 2 ft above water at different speeds graph 

CO vs distance behind boat, 5 feet above water, different speeds, graph

Peak CO 5 feet above water at different sppeds and distances behind boat



And notice this:

Measured at STERN Seat:


 CO levels at different speeds, behind stern seat, average and peak, in PPM




The highest concentrations of CO were measured above the stern seat of the ski boat at slow boat speeds. CO levels averaged 135 ppm at 7.5 mph with peak CO levels measuring 434 ppm. CO levels dropped as speed increased. At 25 mph, average CO concentrations measured 19 ppm with peak readings measuring 110 ppm.

Results of the towed tests showed that CO concentrations:

were highest at the 2 foot level,

were highest at 20 feet behind the tow boat,

tended to remain relatively consistent at distances greater than 20 feet,

at greater distances, tended to increase with boat speed,

tended to average below 35 ppm at distances over 20 feet, and

were higher in the upwind and down wind directions.

Highest CO readings tended to occur during acceleration and tended to last for a relatively short duration. CO levels at 2 feet above the water were higher than CO levels at 5 feet above the water. CO levels were highest at slow speeds, close to the water and close behind the ski boat.

The calmest conditions of 0 to 2 mph wind speeds occurred during the time when the higher speed beam wind data was being collected. Note the asterisks beside that data in Figure 1. The higher numbers suggest that in totally calm conditions, skiers and tubers could ingest more CO than was measured during this study.


CO levels in the stern seat of a ski boat are high enough to be cause for concern. CO levels at 20 feet behind the towed boat are high enough to affect towed tubers who tend to be young children.

CO levels at 5 feet above the water in excess of 60 feet behind the ski boat



Reports/Studies CO Safe Distance Study

All above data and pictures are from that study.