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

[Marc1]

It's interesting to note that a quick search of the internet for CO2 poisoning, produces a series of articles on the subject and most contain a common mistake. They cite the CO2 being 1.5 times "heavier than air" and therefore accumulating at the bottom in confined spaces.

In reality gases don't behave like oil and water and in a confined space, unless there is a source of CO2 that is constantly producing new gas, like in caves from decomposition of organic matter, or silos ... such behaviour of the CO2 gas does not happen. Gas mixes from molecular interaction and from gases movement and the result is a homogeneous mix.

And no, respiration from humans is not a source of pure CO2 that can settle in the bilge. The air we exhale is mostly nitrogen, oxigen and 4% Co2

And plants love it.

[Singularity]

Originally Posted by john61ct

you funny

I provided such calculations here on the same subject last month.

John, it does not appear as though understanding gas science and sensors is your strong suit and gasses seem in general to cause you fear. When the gentleman reported a few weeks ago that two different carbon monoxide sensors were going off after he placed a blower next to his generator, your first question was "are they hydrocarbon sensors." After he said that they were not, that some were old and some where new, your contribution was "[the sensors] need to be replaced every 5 years."

Now you are talking about gases displacing gases, 'wouldn't hurt to have a C02 sensor.' When asked to justify your concerns, you laugh. Others here have expertise on that which you are speculating and giving frankly bad/potentially life-threatening advice about. I'm certain that there are at least dozens here with more expertise than I have on this subject, but none of them step in to have to interact with such foolishness. I really don't know what your motivation is in this thread.

[KiwiKen]

Originally Posted by Don C L

Hence the utility of the self sealing vents?
The longest I’ve been cooped up inside on a passage was, iirc, 5 days, mostly for non-stop spray coming over the boat. Down below was muggy and wet and we really wanted more ventilation. I broke out in an irritating salt water rash all over.
Perhaps I should rethink it, but my frame of reference is a hull with little or no negative numbers in my GZ curve so I imagine, perhaps unrealistically that, we’re it to happen to me, I would not stay inverted for even half a minute. I should keep in mind that if the rig and sails have survived they will offer a good deal of resistance to a recovery from being rolled. If you have seen those videos of Yachting Monthly inverting a more modern hull, it’s clear those may stay inverted for a while until motivated by another large wave.

Depends on the angle of vanishing stabilty, for a mono displacement hull this can be in the order of 16o-165 degrees, so the next wave will bring the boat upright, wide light displacement hulls it can be 110 degrees, which menas that the boat could spend quite some time inverted.
For many multi hulled yachts they are more stable inverted than up right - Covered well in C.A Marchaj's book, Seaworthiness, the Forgotten Factor, that examines the tragedy of the 1979 Fastnet Race

[jtsailjt]

Originally Posted by KiwiKen

Depends on the angle of vanishing stabilty, for a mono displacement hull this can be in the order of 16o-165 degrees, so the next wave will bring the boat upright, wide light displacement hulls it can be 110 degrees, which menas that the boat could spend quite some time inverted.
For many multi hulled yachts they are more stable inverted than up right - Covered well in C.A Marchaj's book, Seaworthiness, the Forgotten Factor, that examines the tragedy of the 1979 Fastnet Race

160-165 degrees would be an extremely high limit of vanishing stability. I can’t think of any cruising yachts with LVS that high. 120-140 is a more reasonable range, but in extreme conditions which would cause that angle to be exceeded, those same conditions are likely to soon cause a roll to less than that number and the boat will then right itself, hopefully before taking on too much water, which would temporarily change the boats LVS to something less, making it less likely to be self righting. So, even though it’s inevitable to take on some water, if it can be minimized by doing things like having companionway closed with hatchboards in, and dorade vents closed off, that helps increase your chances of rolling back upright before you sink.

[Don C L]

Very brief drift, sorry...So this comes out the linked article as an FYI. I can't find the curve for my skinny boat right now but it is a little better (or worse if you like more modern hulls) than the Contessa shown.
https://www.yachtingmonthly.com/yach...atistics-30154

[john61ct]

Originally Posted by Taipe

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!

Exactly my point with this.

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.

[Singularity]

Originally Posted by Taipe

If you [John] 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!

Originally Posted by john61ct

Exactly my point with this.

John, you don't seem to understand basic biology nor perhaps combustion. In responding to Taipe you neglected to quote the parts where he was trying to correct you. I'm certain that on review Taipe would agree that C02 doesn't appreciably concentrate in the bilge.

The products of both human respiration and propane combustion are ~99% water and carbon dioxide. These are the only gases that you could conceivabaly be worried about in terms of volumes displacement of oxygen. ~2,000ppm carbon monoxide will kill a human in 2 hours, this will not displace any appreciable oxygen before it kills.

You don't seem to want to understand that the second you are not taking in sufficient oxygen then carbon dioxide starts accumulating, and that this increase in carbon dioxide immediately starts to cause anxiety and an urge stronger than any other than humans experience...the urge to breath. Most everyone else can figure this out my holding their breathe, but you seem unconvinceable. The concentration of expired air is ~40,000ppm; it would take a very peculiar individual to sit around in a cabin at more than 10,000ppm.

The reason to be pedantic about this issue is that carbon monoxide poisoning is probably the #1 cause of accidental permanent brain damage on a boat while probably no human has ever witnessed any serious event regarding what you are concerned about on a sailboat. A recent thread demonstrated a communal lack of respect/how to appropriate respond to carbon monoxide alarms going off while people in general do not understand how dangerous carbon monoxide is. And you need to focus on your theory here why??

[john61ct]

You are arguing against a straw man you have constructed, for what reason I don't know.

Low O2 caused by too much CO2 is not as immediately critical as that caused by too much CO, as you say, which in turn is not as dangerous as the hull filling with say propane.

Au fond my main point in the thread is that yes low O2 is bad, and if an owner wants to monitor / alarm for that as well as the others, great.

[Singularity]

Originally Posted by john61ct

You are arguing against a straw man you have constructed, for what reason I don't know.

Low O2 caused by too much CO2 is not as immediately critical as that caused by too much CO, as you say, which in turn is not as dangerous as the hull filling with say propane.

Au fond my main point in the thread is that yes low O2 is bad, and if an owner wants to monitor / alarm for that as well as the others, great.

Unicorns carrying ham sandwiches arriving on the boat is also bad. To promote the use of 'unicorn with ham sandwich proximity alarms' suggests exceptional foresight in the unicorn/ham sandwich realm, or a gross misperception on what ordinary people consider to be the myriad of health/safety concerns that exhibit higher-risk threats existing to people on boats. Or it serves the purpose of selling such alarms, to someone.
--
Lost in someone's peculiar unicorn concern is the OP's valid concerns that I think further discussion with him (are you around Pat?) can elucidate. I'm thinking his concern for CO2 incapacitation included consideration of gasses as applied at least in a hyperbaric (sub) environment, +/- a hypobaric (flying) environment. Those specific points can be hashed out but suffice it to say that they don't apply, practically, to people at sea level (who recently haven't been diving/flying).

OP also noted that stale air may contribute to seasickness symptoms. This is a complicated subject unto itself. It certainly stands to reason that high CO2 in the cabin contributes to nausea. But the location on the boat that has the least motion is also the best place to be. Unless, of course, if you're the kind of person who gets relief by being topside why meditating on the horizon trick. Unless you're the kind of person where...and so on. C02 plays a roll, fresh air is better no matter what. But it's practically impossible to attribute everything to carbon dioxide. In fact for the same person carbon dioxide could have been the most exacerbating factor on one trip while the same person seasick on a different trip in different sea state may be unphased by the even high C02 issues but instead made nauseated by a particular frequency of yawing motion.

[thinwater]

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).

I presume he is either joking (farts) or thinking of something like propane.


In fact, high CO2 or low O2 in the bilge is a serious matter in ships. It is not, of course, do to humans, but from respiration of organisms living in the bilge and rust. Bilge spaces are commonly deadly until ventilated. I've seen the readings (one of my employers cleaned ships). Never assume an ventilated space is safe.

[Singularity]

I wish he was joking. Please consider re-reading what was said. He is articulating concern that the ambient effective partial pressure of oxygen would be depleted so as to present a safety concern. The human threshold for smelling propane (per quick google search) is something like less that 1 part per billion, so propane won't displace enough of anything before propane alarms should be going off before you smell the propane. Point being that propane will not displace oxygen to any significant degree before you're dead. The "you will run out of oxygen" in a small boat" thing is a myth.

In a discussion of a sailboat in a blow...to mention death in bilges of large ships, offer admonition against entering closed spaced...is to exemplify why Maslow's hammer isn't called Maslow's multi-tool.

We are talking sailboats/motorsailers here that already should have carbon monoxide and smoke detectors on board (+/- propane if tanks on the boat). Like the boats under probably less than 50 feet, probably in the water, probably with some amount of wave action, probably subject to the laws of thermodynamics, probably having been sailed away from dock for at least an hour. Not holding tanks, submarines, caves/pits, drainage pipes, refrigerators, airplanes, under a house, in a basement, in a trunk, in a freezer, etc ad nauseam.

Again, the pedanticness here is because many people are not up to speed with carbon monoxide, as seemingly simple as it is. To me it makes no sense to talk about unicorns when people have much difficulty we the horse thing and the horse thing is very common.

[Exile]

Not the first time on some of these CF threads, but I'm once again losing the plot.

Singularity -- is your concern that John61, the OP, or someone else is confusing CO2 with CO? Or maybe just equating the two in a way that runs the risk of confusing some who might not be as knowledgeable about the obvious distinctions?

Overall, my takeaway from this thread thus far is that, unlike carbon monoxide (CO) which, as an odorless & colorless gas, can kill while a boater unknowingly sleeps, high levels of carbon dioxide (CO2) and correspondingly low oxygen will prompt enough non-lethal discomfort that a boater would be prompted to remedy by improving ventilation.

Is this the bottom line and, if so, is the installation of an additional alarm for CO2 really necessary or desirable? I say "additional" because it's always seemed obvious to me that alarms for CO and smoke/fire (sometimes one unit) are in fact essential safety equipment on a boat.

[john61ct]

No I am not "promoting" anything, least of all CO2 sensing gear.

[Singularity]

Originally Posted by Exile

Singularity -- is your concern that John61, the OP, or someone else is confusing CO2 with CO? Or maybe just equating the two in a way that runs the risk of confusing some who might not be as knowledgeable about the obvious distinctions?

Overall, my takeaway from this thread thus far is that, unlike carbon monoxide (CO) which, as an odorless & colorless gas, can kill while a boater unknowingly sleeps, high levels of carbon dioxide (CO2) and correspondingly low oxygen will prompt enough non-lethal discomfort that a boater would be prompted to remedy by improving ventilation.

Is this the bottom line and, if so, is the installation of an additional alarm for CO2 really necessary or desirable? I say "additional" because it's always seemed obvious to me that alarms for CO and smoke/fire (sometimes one unit) are in fact essential safety equipment on a boat.

Yes. Bolded parts are the bottom line.
C02 sensor/alarm is not necessary or desirable, all things considered. I referenced the NNT/NNH metric upthread; where the proposed intervention can solve no real problem but has risk associated with implementing the intervention, in typical analysis the intervention is said to be more risky than doing nothing. Advocating for treatment that is worse than the disease is malpractice, or sales.

[Marc1]

I find this thread fascinating.
20 years ago any mention of CO2 "danger" in a boat would have been laughed out the door.
It is only today after two decades of hammering the nonsense of CO2 being a "pollutant" by the "save the planet" lobby, after re-naming it "carbon" and illustrate said (non) danger with cooling towers emitting water vapor, that the confusion between C (carbon), CO, (carbon monoxide) and CO2, carbon dioxide ... and even CH4 (methane) has taken hold of unsuspected minds who tremble at the mention of CO2 that is so bad for you.

Woohoo