@Skierdad by your earlier comment that was not evident that you are "Well aware". Also with a lot of new boaters on this board, it is important to point out the dangers of CO poisoning, especially with respect to our swim platforms. It also builds up in the body and doesn't vacate quickly. The half-life of carboxyhemoglobin is approximately 5 hours. This means that for a given exposure level, it will take about 5 hours for the level of carboxyhemoglobin in the blood to drop to half its current level after the exposure is terminated. Which means multiple short sessions have a period of a long session, this is typically what causes the grave circumstances on a boat. Furthermore it isn't just the amount of time you are exposed, it is also about PPM over time, so a broad statement such as "Not long" is of no significance unless you can determine the PPM rate. A chart below for reference, that I copied.
| PPM CO | Time | Symptoms |
| 35 | 8 hours | Maximum exposure allowed by OSHA in the workplace over an eight hour period. |
| 200 | 2-3 hours | Mild headache, fatigue, nausea and dizziness. |
| 400 | 1-2 hours | Serious headache-other symptoms intensify. Life threatening after 3 hours. |
| 800 | 45 minutes | Dizziness, nausea and convulsions. Unconscious within 2 hours. Death within 2-3 hours. |
| 1600 | 20 minutes | Headache, dizziness and nausea. Death within 1 hour. |
| 3200 | 5-10 minutes | Headache, dizziness and nausea. Death within 1 hour. |
| 6400 | 1-2 minutes | Headache, dizziness and nausea. Death within 25-30 minutes. |
| 12,800 | 1-3 minutes | Death |
IMHO, there really is no safe time to be on the swim platform while the engines are running, even at greater speeds a vacuum dead spot occurs in that area where it can pool. On my boat, no one rides back there while engines are running. It is my responsibility to ensure everyone's safety. It only takes someone to be dizzy or unconscious to fall in the water and drown or hit their head, etc.
This is not to mention the long term effects of inhaling CO over a life time, I am concerned especially for kids what the future ramifications could be.
I can't even tell you how many people I see let their passengers or kids sit on the swim platform as they motor around, unfortunately that is not a wise decision. I couldn't even imagine what it would feel like to know that I had lost someone because I was taking a chance on something simple to avoid.
EDIT: One of the mods that I am wanting to do soon is a CO detector in the back of the cockpit or upper swim platform.
