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

[Don C L]

Originally Posted by Cpt Pat

They admit water when the vents are submerged and the vessel heels past about 90 degrees. These were storm conditions where a knock down or temporary inversion (roll/partial roll) was a possibility.
See also reply 6 below.

So we are talking about Dorade boxes, not just direct air scoops, right? I mean I realize that Dorade boxes will also admit water if submerged. Well I suppose the solution is Dorade boxes that can close themselves, say with lead weights hanging in the vent pipes that would fall into clasps that close and lock, sealing the vent when inverted. I'd be far more concerned about the main hatch and companionway though, but I confess I have not been in a sailboat inverted. I've been in some inverted dories though! and I did almost sink one of those...

[Marc1]

Demonising CO2 has become the sport of the day and a lot of people's income depend on singing from that hymnbook. Even a hint of disagreement with the group thinking is a career ending move.
So not surprise that someone decides to publish a "scientific" paper stating that slightly higher concentrations of CO2 will make people dumb disregarding the obvious fact that low O2 is the culprit. The ample data available of submarines crew tolerating over 10,000 ppm is of course dutifull ignored.

https://wattsupwiththat.com/2012/10/...that-question/

Reminds me of a story from I believe Tom Sawyer's book ( but not sure) ... about that guy who had an ingrown toenail. He was walking along and kicked a root with his sore toe and stumbled, the sudden movement startled a horse that was standing nearby and kicked him in the back. He rolled down the hill and fell in a well and drowned.
On his epitaph it was written "Died from an ingrown toenail"

[boatman61]

Never been a problem for me as I periodically crack open the companionway hatch to take a look around.. quick flush of fresh air at the same time..

[john61ct]

Originally Posted by Marc1

Demonising CO2 has become the sport of the day and a lot of people's income depend on singing from that hymnbook. Even a hint of disagreement with the group thinking is a career ending move.
So not surprise that someone decides to publish a "scientific" paper stating that slightly higher concentrations of CO2 will make people dumb disregarding the obvious fact that low O2 is the culprit.

This really makes me sad

[ShoreFun]

So with all these energy efficient school buildings and the kids getting AC they are finding the kids have troubles learning. It seems the slightly elevated co2 levels have a measurable effect on the students and teachers. It seems there may be a lot of reasons why we need to get the kids outside.

There has been quite a bit of research done on this. A little bit of googling will lead you to a lot of info.

Here is just one of many places to go:
https://www.ncbi.nlm.nih.gov/pubmed/24920413

[CharlzO]

This may have been addressed in one of the articles, I haven't read through them fully. But I'm curious as to the length of time that one would need to be completely locked up in their vessel before levels reach those mentioned. Unless you were inverted for a long time coming, at some point there's no inherent risk in cracking a hatch for a few minutes to refresh the air supply. Obviously things are closed down in rain and stormy weather, but I'm betting common sense tells us to get a breath of fresh air at the risk of a little rain on the head - and less an issue if you have a dodger or something you can do with. But the only fully closed-down scenario would be in the imminent threat of knockdown, and I would think it's a rare occasion that someone find themselves in a weather system to where you would need to be canned up for a length of time with zero hope of opening anything back up even momentarily.

[john61ct]

Yes and having a cheap but effective sensor beep to remind you

if that gives you peace of mind

seems entirely reasonable.

Especially as a complement to propane / CO detectors

[Singularity]

Originally Posted by john61ct

if that gives you peace of mind

seems entirely reasonable.

A false sense of security is the reason it's not reasonable. It's one thing to appreciate that some people speed in their car knowing that they have belts/airbags. When the car manufacturer also touts the car as having an additional life-saving sensor (technically a fart sensor) ordinarily humans will have increased peace of mind and will increase risk-taking behavior (unless they understand that the fart sensor thing is a gimmick).

On these finite cognitive tests...fwiw:
Lots and lots of things make your IQ score transiently drop. The brain is merely a computer/huge integrated circuit. If you increase resistance (C02 accumulation) then throughput ordinarily is diminshed. Have a shot of rum, decrease voltage across the entire circuit. Have a large meal, decrease the amperage. Overload the brain with 3-axis constantly changing motion where the brain has to reconcile pressure sensors from all over the body with visual and vestubular/inner ears inputs...(motion sickness)...ultimately increased resistance plus decreased voltage and amperage. But this all reverses.

Short-circuiting connections in the brain does not reverse. This is what carbon monoxide does. Recently here someone reported his monoxide sensors x2 went off after installing blowers about his generator. The responses, like a Monty Python skit, were akin to "well, you know those sensors go bad...maybe have them tested...see what happens."

It does not seem reasonable at all to discuss, effectively, fart sensors in a place when people (understandably) have difficulty distinguishing between a fart sensor and a carbon monoxide sensor, no less what to do about it when your "look's like you're about to really die" sensor is going off.

I don't mean to jump on you Pat...sincerely. But the C02 thing has merit with respect to getting fresh air for motion sickness etc, but context is everything.

[wingssail]

I really have to wonder why there is this much attention being paid to a pretty much unlikely situation. Buying a C02 monitor in case you might be sealed up below decks with several people? Worrying about water ingress through a dorade vent during a capsize?

How about this: Instead why not spend the mental energy learning to avoid storm prone areas and how to manage the vessel in heavy weather if you are hit. There is generally a benefit to continuing to sail the boat, so put somebody on watch, or at least send them on deck every short while. Opening the hatch will exchange the air.

The rarity of that type of storm, where you can do nothing but huddle below deck and hope for the best, is hard to overstate.

In 55,000 ocean miles over 20+ years we never even came close to those conditions. Yes, they can happen, but you are far better off focusing on the hazards and dangers you will face day in and day out than living in fear of the remote disaster which never happens. If that is your approach, maybe you should stay safe at home.

Virtually all sailboats out there sailing can handle all but the absolute worst storms. So, get out. Sail your boat. Sail in all conditions. Learn how it handles in heavy weather. Learn how to analyze the weather and stay out of the bad stuff. You'll enjoy it a lot more.

[Taipe]

Those that caution against leaving a dorade open during storm weather are absolutely right. And, not a good idea to try to thread the cap back on in a bad blow. However, don't get overcome with fear about needing to keep everything closed. Keep the main sliding hatch open about an inch or so with a hook clasp to keep it from opening further. That can then be secured in the event of a pitch pole or knock down.

Question: Do you have storm curtains under your sea berths that are ready for quick attachment to the overhead? - For reducing risk of head injuries and lacerations which occur much more frequently than sinking from capsizing.


Btw, just to keep in mind, the increased need to breath and to breath deeply is not stimulated by low levels of oxygen in the blood, it is stimulated by high levels of carbon dioxide.

[hellosailor]

You might bring your concerns up to the ISF/ORC since these are signficant safety questions. And, with some patience, you may be able to contact someone in the USN or other submarine service--where they have long ago documented air quality issues in closed spaces, and the effects they can have on crew. NASA would also have that information, they can't afford to have the wrong gas mix/concentration in a closed space.

It may not be readily accessible, but the information is out there. I'd expect it to be out there somewhere on the web, since it shouldn't need to be classified.

[MarkSF]

Originally Posted by Suijin

I take off my dorado scoops and put in the plates if I'm taking a long passage offshore. A 4" dorade can in theory let in 250 gallons/min. So if you roll and stay capsized, with two dorades, within two minutes you could be looking at 1000 gallons in the boat or 8000 pounds of water. Of course it's going to be a lot less than that, practically speaking, but they are holes in the boat.

Overly cautious? I'd rather minimize risk and leave one less thing to do if the weather turns bad, and just open some port lights/hatches occasionally for air circulation.

Mine have an intake about 4", maybe bigger in fact, but the holes that allow air into the boat, in the deck, are only about 2.5". Surely the smaller hole is the limiting factor?

[Montanan]

Dang, certainly someone will have farted long before you emitted too much CO2 and thus everyone will have run for the deck to get some fresh air until the stench dilutes.

Dorades facing away from the wind and the waves with fans are the answer to providing ventilation and mitigating water intrusion. One dorade's fan blowing intake and one dorade's fan blowing outbound. Dorades whose entry point is downwind tends to provide for little air entry, but can provide for an induced vacuum pressure depending on wind velocity and design so as to enhance air exfiltration but you need a differential in pressure between two points to derive air movement from the higher pressure to the lower pressure. If you have only one dorade open it will not avail much air exchange. If you have two open with one catching air deriving positive pressure and the other oriented downwind deriving a vacuum then you will have derived cross ventilation. Whereas two dorades both facing up wind or down wind will avail little to no cross ventilation because there is little to no pressure differential between them. Midline ship mounted dorades are best suited to mitigating water infiltration in the event of a brief knock down as they likely will remain above water.

No different than being in a camper or a tent or a SuperGoodCents home. Ya got to let air in and out or you will become ill, deranged and die.

[Montanan]

If conditions are as bad as you describe, typically someone or everyone is throwing up and the smell of puke will inevitably require ventilation, otherwise dry heaves will prevail, a different version of heaving-to during a storm.

I have "hove-too" after others have also heaved below.

[Suijin]

Originally Posted by MarkSF

Mine have an intake about 4", maybe bigger in fact, but the holes that allow air into the boat, in the deck, are only about 2.5". Surely the smaller hole is the limiting factor?

Indeed it is. It's a function of the area of the opening, the obstruction to water flow (the baffle on deck) as well as the water pressure sustained.

That said, if I'm capsized, two things are probable 1) I'm injured and dazed 2) The coach roof ceiling (now the floor) is covered with everything that has dumped itself onto it, which in my case is considerable despite my best efforts to secure everything. Books, the contents of my nav table, probably the contents of my refrigerator and spice rack, dishes and pots that may have been in the sink, pictures, clothes, cushions, fruit from the hanging nets, various paper, and maybe some human bodies. There's a lot to do that that point. If I can focus on making sure everyone, including myself is OK and attend to medical issues instead of trying to block two fountaining holes in the (now) floor at the expense of what constitutes weak ventilation to begin with, I'm going to do it. Takes two minutes to swap the plates for the scoops on the coachroof. It's just part of my offshore routine which includes various other stuff like taping gate pelican hooks, putting clips on the cockpit locker latches, etc.