Shocking Finding- CO Readings in Cockpit

[spimik]

The topic of CO with a camper top has been discussed at length here and I want to thank everyone for their thoughts- it got us thinking this winter as we were adding a camper top to our '08 330.

We spent 4 hours on the boat yesterday with a highly technical IAQ meter- the TPI 1010. This is a very accurate, highly calibrated test meter that measures both CO and C02 along with ambient temperature and humidity. Our findings were somewhat shocking, at least to us.

With the center piece of window isinglass and the canvas at the walk-thru removed, and ALL of the screens in the camper top fully rolled down, we registered cockpit CO readings all day yesterday between 16ppm and 173ppm at rpms of 900-1500. (Our normal cruise rpms)

I found this information on the web with respect to CO levels:

At what level does carbon monoxide become toxic?
For healthy adults, CO becomes toxic when it reaches a level higher than 50 ppm (parts per million) with continuous exposure over an eight hour period.. When the level of CO becomes higher than that, a person will suffer from symptoms of exposure. Mild exposure over a few hours (a CO level between 70 ppm and 100 ppm) include flu-like symptoms such as headaches, sore eyes and a runny nose. Medium exposure (a CO level between 150 ppm to 300 ppm) will produce dizziness, drowsiness and vomiting. Extreme exposure (a CO level of 400 ppm and higher) will result in unconsciousness, brain damage and death.

It was shocking to see how quickly CO accumulated in the cockpit when variations to the direction and speed of the boat where made. The only time we registered a 0ppm reading was when we were up on plane and moving. The meter is factor set to alarm at 30ppm and it was in constant alarm mode pulling in and out of our slip- as soon as the engines were fired up, the CO level exceeded the 30ppm alarm setting.

It was a cooler day and we passed dozens of Sea Rays/Cruisers yesterday with ALL of the camper canvas up- I wonder what levels they were experiencing.

Our custom camper top installer told us when we asked him about the station wagon effect with a camper top- he said "As long as you have the walk thru window cracked open and the back isinglass open a bit, it will create enough air flow to clear the cockpit." He has no idea what he is talking about. I would suggest that this why Sea Ray does not offer a camper top in the 30+ foot range. They must know something about C0 levels and do not want to assume the liability.

 

[Sadler]

Great information. Several years ago, a boating friend suggested I get a digital readout CO detector for the cockpit. It was a good idea, and ever since I've kept one on the dash in front of me whenever running with the camper windows closed up. I wish it was hard wired, but all I've found is a battery powered one, so I pull the batteries out when not using it to keep the batteries from dying. Like you found, as soon as the engine fires up the readings starts to climb, and until we get on plane it won't fall, almost no matter what. It's crazy the canvas configurations that give no buildup when on plane. Many times, zipping the canvas up completely gives the zero reading, whereas opening the middle and back Isinglass brings the reading way up.

 

[spimik]

Sadler- thanks for the response- I am glad you brought up zipping up the canvas completely- my wife and I talked about this last night and want to try that. We love the additional room and the new feel that the camper top gives us- our own floating gazebo of sorts and we are very happy with how it turned out. We wondered if we had in fact created our own problem with having too much open area.

It would be nice to enjoy a longer season with the camper top offesetting cool wet weather and I am hoping that we find that with all of the canvas done up that the CO is at an acceptable, (<30ppm) level.

 

[Go Aweigh2452]

Sadler- thanks for the response- I am glad you brought up zipping up the canvas completely- my wife and I talked about this last night and want to try that. We love the additional room and the new feel that the camper top gives us- our own floating gazebo of sorts and we are very happy with how it turned out. We wondered if we had in fact created our own problem with having too much open area.

It would be nice to enjoy a longer season with the camper top offesetting cool wet weather and I am hoping that we find that with all of the canvas done up that the CO is at an acceptable, (<30ppm) level.

Since you have the meter already, it would be interesting to see if you could duplicate the readings when running the bilge blower while cruising. If you get a chance, I'd like to know what the results of that would be... Might change the way we run by having the blower going prior to being on plane.

 

[spimik]

Doug- the bilge was on the entire day- we use it at all speeds but full flight. However, I don't think that it would make a difference. I think the CO is entering via the transom in a station wagon effect. My understanding of the bilge blower is that is is designed to clear potentially combustible gas from the bilge to prevent and explosion/fire and would have no effect on the CO entering the boat.

My Mercruiser manual actually shows two illustrations of the station wagon effect and warns about it.

 

[sbw1]

The safe way to run with canvas up is to use a drop curtain instead of an aft curtain or camper top. Running a blower has no effect on CO in the cockpit. Blowers ventilate the bilge not the cockpit.

 

[tobnpr]

I don't think camper enclosures were ever envisioned to be in place while the boat is running. To me, it's just like pitching a tent in the cockpit for camping- put it up when you arrive at your destination, take it down when you leave.

 

[spimik]

I don't think camper enclosures were ever envisioned to be in place while the boat is running. To me, it's just like pitching a tent in the cockpit for camping- put it up when you arrive at your destination, take it down when you leave.

I do agree with your point.

We've boated our entire lives, always ran smaller 17-21' runabouts, so the world of sport cruisers is all new to us as of last summer. I would suggest that almost 90% of the Sea Ray cruisers that run in our area all sport a camper top, and most of these operate in the early and late season with the camper in place. (Our season is so short, that if the camper can add an additional 2 weeks to the front and back of the year, it is easy to understand why they are so popular.) I am just not confident that most owners understand the level of CO that is present when they are underway.

Your advice is appreciated, our plan is to remove all canvas and issinglass when we leave the dock. We would only put it up if we encountered rain in order to make a dry run back to our slip. Yesterday was meant to uncover exactly how the camper top reacted while underway.

My neighbour, a 340, wants to borrow the tester this coming week since he runs with his camper in place 100% of the time, he just rolls down the issinglass. I think he may change his mind when he sees the results.

 

[wkearney99]

...I am hoping that we find that with all of the canvas done up that the CO is at an acceptable, (<30ppm) level.

Bear in mind that CO poisoning is a cumulative risk. The longer you're exposed, the greater the danger. Even more so when dealing with small children. So don't let a low figure mislead you, take into account the total length of time. I've not run across any detailed info on how much is dangerous, over how long a time. Nor any clear numbers on how long you have to be removed from the exposure to eliminate the risk. It would be good to know more about it.

 

[Sadler]

I should have stated that we don't run with the canvas up if the CO level on the detector is above zero. If I can't get it to zero, we take curtains down. I may run with the canvas up once or twice a year probably, and that's if it happens to be a very cold day, or if we get caught in a rainstorm.

 

[spimik]

Bear in mind that CO poisoning is a cumulative risk. The longer you're exposed, the greater the danger. Even more so when dealing with small children. So don't let a low figure mislead you, take into account the total length of time. I've not run across any detailed info on how much is dangerous, over how long a time. Nor any clear numbers on how long you have to be removed from the exposure to eliminate the risk. It would be good to know more about it.

Absolutley- great point. Our business, HVAC, deals heavily with issues such as CO with cracked furnace heat exchangers and IAQ issues. An adult is fine at 30ppm or less for long periods of time. The trouble starts at about 50ppm, but even at that, it takes about 8 hours of continuous exposure to feel any real effects. (headache, nausea, etc.) At 400+ppm, you won't wake up.

I think if you took the meter I used yesterday and ran it in your car during rush hour you would be shocked. We plan to try this now that we have uncovered this issue. I will bet that we will see high levels of CO when we do this. The bottom line is CO is out there. When you burn a fossil fuel, you create a number of by products- CO is one of them.

I just wanted to bring it to the attention of all camper top owners since I see most of them in our area operating with some if not all of the pieces in place, especialy during the spring and fall.

 

[JV II]

What if you keep the rear panels in place, zipped up and roll up the side windows and remove the front center window? There is no station wagon effect in a station wagon driving with side windows down.

 

[spimik]

What if you keep the rear panels in place, zipped up and roll up the side windows and remove the front center window? There is no station wagon effect in a station wagon driving with side windows down.

Great idea- we will try this combination. Our plan is to work on a number of variables with the canvas to find what works best. I will advise.

 

[JV II]

Running a blower has no effect on CO in the cockpit. Blowers ventilate the bilge not the cockpit.

And, there's no CO in the bilge anyway (at least there isn't supposed to be any). Even if the blower vented the cockpit, let's say you had a big hole in the deck, the negative pressure created by the blower would be sucking in more of that CO from outside the boat. To keep CO out of the cockpit you need moving air from the bow to the stern OR positive pressure inside the camper top. CO would be a 0% inside a closed camper top if you ran a blower in reverse (drawing air from the front of the boat), creating positive pressure inside the camper top.

Here's the blower and CO connection: Exhaust leaks.
If you have a generator running in the bilge and you have an exhaust leak, you die as the CO permiates through the bulkhead. You stand a chance of living longer if the blower is on. Who wants to test that theory?

If you have an engine exhaust leak, there may be CO entering the cabin, but engine requires more air than the volume of your bilge so it clears the bilge of most of that CO. With the blower on, you are safer.

How many people on this board know for certain that their engines and generators are not leaking any exhaust into the bilge? Maybe you should run that blower.

 

[Presentation]

What if you keep the rear panels in place, zipped up and roll up the side windows and remove the front center window? There is no station wagon effect in a station wagon driving with side windows down.

+1

Great idea- we will try this combination. Our plan is to work on a number of variables with the canvas to find what works best. I will advise.

Please do let us know. This is what we do during cooler weather.

My theory is the air enters via the open front middle and creates positive air pressure in the cockpit. All the rest are closed. Air can not come in anywhere else, only go out.

At least that is my theory and its what we do.

 

[Woody]

+1



Please do let us know. This is what we do during cooler weather.

My theory is the air enters via the open front middle and creates positive air pressure in the cockpit. All the rest are closed. Air can not come in anywhere else, only go out.

At least that is my theory and its what we do.

We rarely run with any aft canvas up but when we do I only open the front as you do.

 

[Loneranger]

Interesting information. I just replaced all of the CO monitors on my 270 Sundancer. I have been planning on getting a quantitative gauge to do some of the same testing you are.

You have a very expensive piece of equipment:

http://www.professionalequipment.com/tpi-indoor-air-quality-iaq-meter-1010/indoor-air-quality/

You would not happen to know of a reasonably accurate CO quantitative gauge that is not quite so expensive?

John

 

[Sadler]

Interesting information. I just replaced all of the CO monitors on my 270 Sundancer. I have been planning on getting a quantitative gauge to do some of the same testing you are.

You have a very expensive piece of equipment:

http://www.professionalequipment.com/tpi-indoor-air-quality-iaq-meter-1010/indoor-air-quality/

You would not happen to know of a reasonably accurate CO quantitative gauge that is not quite so expensive?

John

$37.49
http://www.castlewholesalers.com/KIDDE-900-0146-Battery-Operated-Carbon-Monoxide-Alarm.html