I'm cutting and pasting a response that Larry Mann posted a year or so ago. Larry of Fresh Air Exhaust is, in my opinion, one of the leading authorities on CO posioning and wakesurfing. It would have been so easy for the
reporter to get Larry's input, instead they find a few folks that are principally uninformed.
The CO issue isn't a NON-concern, but we currently have a much better understanding of how to mitigate the risks. One OTHER reason folks shouldn't ride on the sun pad:
http://www.wakeworld.com/MB/Discus/m...tml?1137633497
Derby
If you put a Carbon Monoxide (CO) alarm at the stern of the boat, outside, above the swim platform, it will be alerting constantly. If you put it inside, in front of the rear seat of either a direct drive or v-drive boat, it will seldom, if ever, alert.
I will explain some of our findings to better elucidate the situation. If you are idling, the back seat (direct drive) or engine cover (v-drive) CO levels can reach in excess of 1000ppm in under a minute. Once you begin moving, the CO drops dramatically to mostly safe levels.
On a direct drive boat, it’s as if there is a wall just above the transom. Behind the "wall" the CO levels are high, in front of the "wall", the levels are low. If you are traveling slowly, like in a no wake zone or wake surfing, a tailwind can push the CO further into the boat. Also, if someone is sitting in the rear seat, their torso and head can create an eddy current that draws the exhaust forward. Let's say a child is sitting in the rear seat of a fast moving boat, no problem. If the boat were slower, still likely no problem; but, if the child were to turn around and face the rear, an eddy current could form and pull exhaust and CO into their face.
On a v-drive boat, a similar situation exists; but now we are talking about a person (with no life vest) sitting on the engine cover. As I stated previously on this thread, over the engine cover of a V-drive boat set-up for wake surfing, I have measured CO levels in excess of 500 ppm. This same boat had 180 ppm of CO inside the boat, in the back seat, at 17 mph (and this was a brand new boat).
In both of the above scenarios, a CO meter mounted inside the boat would be unlikely to give any indication of what was happening to the person sitting in the rear of the boat.
The worst conditions for CO for passengers in the boat:
Slow (10 mph), engine under load (lots of ballast), heavy in the rear (a high bow creates more eddy current), people sitting in the rear at the lowest point, facing rearward. I just described wake surfing.
So how dangerous is this really? There is one documented case I am aware of where a person sitting in the back seat of a boat, towing another boat, was dead from CO poisoning when they reached shore. One person (who now has Fresh Air Exhaust on his boat) had 2 girls rushed to the hospital with CO poisoning after a few hours of sitting in the rear of the boat watching wake surfing.
A healthy person breathing the typical levels of CO in these scenarios will probably just feel ill and get a headache. Young children, the elderly, a pregnant woman’s unborn child, and anyone with heart or lung disease could suffer more harm.
Larry Mann
www.FreshAirExhaust.com
reporter to get Larry's input, instead they find a few folks that are principally uninformed.
The CO issue isn't a NON-concern, but we currently have a much better understanding of how to mitigate the risks. One OTHER reason folks shouldn't ride on the sun pad:
http://www.wakeworld.com/MB/Discus/m...tml?1137633497
Derby
If you put a Carbon Monoxide (CO) alarm at the stern of the boat, outside, above the swim platform, it will be alerting constantly. If you put it inside, in front of the rear seat of either a direct drive or v-drive boat, it will seldom, if ever, alert.
I will explain some of our findings to better elucidate the situation. If you are idling, the back seat (direct drive) or engine cover (v-drive) CO levels can reach in excess of 1000ppm in under a minute. Once you begin moving, the CO drops dramatically to mostly safe levels.
On a direct drive boat, it’s as if there is a wall just above the transom. Behind the "wall" the CO levels are high, in front of the "wall", the levels are low. If you are traveling slowly, like in a no wake zone or wake surfing, a tailwind can push the CO further into the boat. Also, if someone is sitting in the rear seat, their torso and head can create an eddy current that draws the exhaust forward. Let's say a child is sitting in the rear seat of a fast moving boat, no problem. If the boat were slower, still likely no problem; but, if the child were to turn around and face the rear, an eddy current could form and pull exhaust and CO into their face.
On a v-drive boat, a similar situation exists; but now we are talking about a person (with no life vest) sitting on the engine cover. As I stated previously on this thread, over the engine cover of a V-drive boat set-up for wake surfing, I have measured CO levels in excess of 500 ppm. This same boat had 180 ppm of CO inside the boat, in the back seat, at 17 mph (and this was a brand new boat).
In both of the above scenarios, a CO meter mounted inside the boat would be unlikely to give any indication of what was happening to the person sitting in the rear of the boat.
The worst conditions for CO for passengers in the boat:
Slow (10 mph), engine under load (lots of ballast), heavy in the rear (a high bow creates more eddy current), people sitting in the rear at the lowest point, facing rearward. I just described wake surfing.
So how dangerous is this really? There is one documented case I am aware of where a person sitting in the back seat of a boat, towing another boat, was dead from CO poisoning when they reached shore. One person (who now has Fresh Air Exhaust on his boat) had 2 girls rushed to the hospital with CO poisoning after a few hours of sitting in the rear of the boat watching wake surfing.
A healthy person breathing the typical levels of CO in these scenarios will probably just feel ill and get a headache. Young children, the elderly, a pregnant woman’s unborn child, and anyone with heart or lung disease could suffer more harm.
Larry Mann
www.FreshAirExhaust.com
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