Riding out a storm, sealed up tight down below. Watch out for CO2.

[john61ct]

Actually three people sleeping in a van in arctic conditions, the first night we had everything closed up, and yes, woke up choking and covered in sweat middle of the night, desperate struggle to pop the doors open ASAP.

From then on always cracked two windows at opposite ends.

[Exile]

Originally Posted by john61ct

Actually three people sleeping in a van in arctic conditions, the first night we had everything closed up, and yes, woke up choking and covered in sweat middle of the night, desperate struggle to pop the doors open ASAP.

From then on always cracked two windows at opposite ends.

From the depletion of oxygen? Or the corresponding increase in CO2?

[Singularity]

Originally Posted by a64pilot

I don’t know about you guys, but in high winds especially, there is no way to seal my boat up to the point that it’s even a consideration.

^^^^^^^^^^^this.

Renovating the interior of my boat (much sanding residue, no vapor chemicals) I have to seal everything up just to avoid a constant ~snowstorm...this with just a gentle breeze topside.

[john61ct]

Originally Posted by Exile

From the depletion of oxygen? Or the corresponding increase in CO2?

I do not care to distinguish between the two as a practical matter. From my response post #2

Originally Posted by john61ct

Yes low O2 is just as important as propane/hydrocarbon fumes and CO detection.

[Exile]

Originally Posted by john61ct

I do not care to distinguish between the two as a practical matter. From my response post #2

Yes, as a practical matter it makes little difference. I'm inclined to agree with others that, even with dorades sealed & main hatch closed, I don't think my boat is sealed up enough for oxygen depletion/CO2 increase to become a problem beyond discomfort. Maybe a van/auto would be different since all the doors & windows are pretty well sealed.

[thinwater]

Originally Posted by Exile

From the depletion of oxygen? Or the corresponding increase in CO2?

• OHSA defines oxygen deficient as a drop of 1.4% in O2. On the other hand, it is 5% lower in Aspen all the time.
• OSHA limits CO2 to 5000 ppm (0.5%) for 8 hours.
• Low O2 and high CO2 are synergistic. The effects of each are increased by the other.

It will consume 0.4% of the O2 to produce 0.5% CO2. For the O2 to drop 1.4%, about 20,000 ppm CO2 will be generated. At 40,000 ppm, CO2 is considered "immediately dangerous to life and health."



Thus, they are closely related. In this case, they almost certainly happen at the same time.

[Singularity]

Originally Posted by Exile

Yes, as a practical matter it makes little difference. I'm inclined to agree with others that, even with dorades sealed & main hatch closed, I don't think my boat is sealed up enough for oxygen depletion/CO2 increase to become a problem beyond discomfort. Maybe a van/auto would be different since all the doors & windows are pretty well sealed.

As a practical matter, completely remove low oxygen concerns from the radar screen on a sailboat (or car/van/truck for that matter) unless you're drugged/drunk/carrying dozens of pounds of dry ice. Blood C02 drives your breathing situation (for all intents and purposes here). If unconvinced, hold your breath with a pulse-ox on your finger after jogging for a minute.

"small fluctuations around this set-point [baseline blood CO2] are not consciously perceived and have no impact on the state of vigilance. By contrast, large acute increases in PaCO2 (e.g., from airway blockade, diving, sleep apnea, bronchial disease and accidental or experimental exposure to CO2) produce noxious sensations in awake subjects (dyspnea, urge to breathe, panic) and arousal from sleep"
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4559867/

Other chemistry concerns are present if your sailboat is at 18,000 feet, at which time I assume you have other concerns besides the other concerns. <---joke loosely stolen from another poster when we last discussed the C02 myth a couple months ago here.

[john61ct]

If your low O2 is caused by high levels of a gas other than CO2, then you've got bigger problems.

[Singularity]

Originally Posted by john61ct

If your low O2 is caused by high levels of a gas other than CO2, then you've got bigger problems.

Your point is specious and fear-mongering if not substantiated.

Which precise gases in about what total concentrations from which precise sources are you contending to potentially cause a problem? Please show your logic and math. Numbers. It's perfectly straight forward to calculate (leeway granted for boat internal volume and leakage).

[gonesail]

Originally Posted by gmakhs

I wonder why you close dorade boxes ??? Mine they don't leak at all , and even if the boat capsize the water intrusion for then will be little.

a dorade box will leak very much if the boat is upside down.

[john61ct]

Originally Posted by Singularity

Your point is specious and fear-mongering if not substantiated.

Which precise gases in about what total concentrations from which precise sources are you contending to potentially cause a problem? Please show your logic and math. Numbers. It's perfectly straight forward to calculate (leeway granted for boat internal volume and leakage).

you funny

[hamburking]

Originally Posted by SuW

I know from personal experience that seasickness can make you very stupid. Not to mention headaches, nausea, and so on.

Agree. Stuck below in rough weather, no fresh air, not good. On an ocean passage often people are not eating or drinking (water) enough either. This also makes it worse. I personally suffered greatly when crossing the atlantic with a mentally unstable skipper. Lethargy and hostility were rampant. Alcohol made it worse. Then running out of alcohol made it MUCH worse.

[Exile]

Originally Posted by thinwater

• OHSA defines oxygen deficient as a drop of 1.4% in O2. On the other hand, it is 5% lower in Aspen all the time.
• OSHA limits CO2 to 5000 ppm (0.5%) for 8 hours.
• Low O2 and high CO2 are synergistic. The effects of each are increased by the other.

It will consume 0.4% of the O2 to produce 0.5% CO2. For the O2 to drop 1.4%, about 20,000 ppm CO2 will be generated. At 40,000 ppm, CO2 is considered "immediately dangerous to life and health."



Thus, they are closely related. In this case, they almost certainly happen at the same time.

Yes, and understood. And plugging in some numbers to highlight the point was instructive, thanks. My comment was a bit tongue-in-cheek, given the thread title and the focus on the dangers of excessive CO2 in the climate change debate. It's become quite the bogeyman generally but not quite sure it's a culprit here.

On the contrary, my main takeaway from the thread comes from Suijin's practice of having dorade boxes capped when he's offshore in challenging conditions. Thanks Suijin!

[StuM]

Originally Posted by thinwater

It will consume 0.4% of the O2to produce 0.5% CO2.
For the O2 to drop 1.4%, about 20,000 ppm CO2 will be generated. At 40,000 ppm, CO2 is considered "immediately dangerous to life and health."

To get to 20,000 PPM, O2 concentration actually will drop by more than 2% (see below)



To answer the initial issues, you really need to take into account volumes and time.



Air initially contains about 21% O2 and 0.04% CO2.
Assume a completely sealed interior volume of about 50,000 litres for a 40ish foot boat. That will initially contain about 10,500l of O2 and 20l of CO2.



At rest, a person will breathe about 1000 litres per hour, consuming about 23 l/h of O2 and generating about 20 l/h of CO2.


(In the following calculations, I will ignore the 3 l/h reduction in the 50,000l initial volume.)


So one person will recycle that 50,000l once in 50 hours and in 24 hours, they will recycle roughly half of it


Consequently, in one day that person will consume about 575l of oxygen and generate 500l of CO2. Resulting in 9925l of oxygen and 520l of CO2


So the resultant concentrations after one person breathing for one day are 19.85% O2 and 1% CO2 (10,000 ppm). By this stage, you will be suffering from noticeable symptoms.

After two days, or 2 people for one day, it would be 9400l O2 and 980l of C02 which is 18.8% O2 and 2% CO2 (20,000 ppm). By that stage you will be suffering severe symptoms.





US OHSA "Respiratory Protection Standard considers any atmosphere with an oxygen level below 19.5 percent to be oxygen-deficient and immediately dangerous to life or health."


So it's very much a situation of dangerous levels of both CO2 and O2 go hand in hand.

[Taipe]

Originally Posted by john61ct

I do not care to distinguish between the two as a practical matter. From my response post #2

If you mean to say that one is as bad as the other, I don't agree. The reason I pointed out the difference in the brain response between the two is because dangerously high levels of CO2 are much more likely to get a person gasping for air and opening up a fresh air vent than a dangerously low O2 level. That's just the way the brain works. But, I think it would be uncommon to find dangerously high ambient CO2 levels inside a boat, except maybe down in the bilge, being a relatively heavy gas. In the main cabin, it would likely be a very tightly enclosed day sailor with more than just a few people packed together like sardines in a can. Air problems on a tightly enclosed boat are more likely to be caused by open-flame burners using up oxygen and polluting the air with carbon monoxide, which together can easily starve red blood cells for oxygen. And, we all know what that can do!