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Old 04-06-2020, 06:41   #1
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Mini scuba tanks instead of escape hatches?

Our newly bought (second hand) Schionning does not have any escape hatches and we want to avoid building them in. We are considering the purchase of small scuba tanks, 0.5 or 1 l, to be used in an emergency situation (boat upside down and you need to escape out of one of the hulls). They could also be used for a quick inspection dive. Is there anybody out there who can share his/her experience with one of these tanks? Plus: There are some comparatively cheap Chinese ones on the market, which come with a manual pump. We cannot imagine that this will work. Again: Can you share your experience?
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Old 04-06-2020, 06:49   #2
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Re: Mini scuba tanks instead of escape hatches?

Hi,


we also just bought a catamaran without escape hatches.



I plan to add them next winter, building them with sandwich laminate and not a standard see-through escape hatch.


I don't like the idea of using the small scuba tanks as a replacement. What if more than one person need to evacuate from a hull? Will you always make sure, they are filled and working?



Paul
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Old 04-06-2020, 07:17   #3
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Re: Mini scuba tanks instead of escape hatches?

I have the cheap Chinese item with the pump.

Lubricate the pump with virgin olive oil.
It is important not to introduce any hydrocarbons into the breathing mix.
I've plumbed an activated charcoal filter to the fill line.
The filter sits in an aluminium (pressure) housing with a condensate reservoir and drain.

The air quality is good for shallow work.

I have a tether so I can't drop it bite fails.
Prop rudder & keel on first fill.
Assistant pumps while in water person does the waterline.
Second fill take care of the rest.

Consider the effect of disorientation when you wake @ 02:30 to a flooded hull and have to locate & operate breathing apparatus then negotiate a debris field to exit in open water.
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Old 04-06-2020, 07:24   #4
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Re: Mini scuba tanks instead of escape hatches?

I bought one of the cheap Chinese ones but have never tried it. How long does it take to pump it to full? How long does it last in 1-2m of water?

And on topic: No way I would substitute escape hatches with something like this
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Old 04-06-2020, 07:48   #5
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Re: Mini scuba tanks instead of escape hatches?

Hi. Please visit any scuba diving store and talk to someone who is a certified instructor. They will explain how easy it is to cause severe lung damage or death on compressed air. Learn about shallow water blackout. You could go to PADI.com and read up on the subject. You might find a Police dive team to question.
I’m a PADI pro and have been diving for 60 years. I have a titanium knife for fishing line , sail material, running rigging but it will not cut wire. Well equipped professional divers sometimes carry small spare air tanks. They are experienced, properly trained and aware of the serious dangers involved. Why do you think divers have a dive buddy and a second regulator and are taught how to share air.
Please...please do not do this without gaining more knowledge of the dangers you face. Ask any police diver who has recovered a body.
Manatees sleep on the bottom for 15 minutes, grab a breath, and drift back down to sleep. I’m not a manatee...it’s a nickname from my work with manatees.
Do not use any source of compressed air without certified training.
Mark the manatee.
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Old 04-06-2020, 08:04   #6
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Re: Mini scuba tanks instead of escape hatches?

Quote:
Originally Posted by Rucksta View Post
I have the cheap Chinese item with the pump.

Lubricate the pump with virgin olive oil.
It is important not to introduce any hydrocarbons into the breathing mix.
I have some bad news for you: olive oil IS a hydrocarbon. Inhaled as a vapor or mist it is almost as bad for your lungs as refined petroleum oils, and in the heat of a compressor can still breakdown and produce carbon monoxide.

And why VIRGIN olive oil? Is the oil from first pressing of the olive different in toxicity from the later pressings? As a LESS refined oil it actually has a wider variety of other chemicals in it that give it odor and taste. And why OLIVE oil? there are other plant oils that are more stable to high temperatures, and are more highly refined and purer.

Trust me, the Chinese maker of this doesn't really care about your lungs, just your wallet.
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Old 04-06-2020, 08:10   #7
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Re: Mini scuba tanks instead of escape hatches?

Are you going to be able to reasonably dive down with a lung for of air, navigate out of a hull and find the main hatch, more than likely in the dark?
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Old 04-06-2020, 08:28   #8
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Re: Mini scuba tanks instead of escape hatches?

Quote:
Originally Posted by SVHarmonie View Post
I have some bad news for you: olive oil IS a hydrocarbon. Inhaled as a vapor or mist it is almost as bad for your lungs as refined petroleum oils, and in the heat of a compressor can still breakdown and produce carbon monoxide.
Thanks for the warning.
Air tests OK on olive oil.
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Old 04-06-2020, 08:31   #9
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Re: Mini scuba tanks instead of escape hatches?

Maybe you are dive-trained but you didn't say so. If not, as a long-time diver, NAUI and then PADI recertified after years away from diving, I strongly advise you get training before using any bottles, regular or pony. Breath-holding even from modest depths can can serious damage.
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Old 04-06-2020, 08:42   #10
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Re: Mini scuba tanks instead of escape hatches?

If you've never seen a capsized/wrecked vessel you can't imagine how much debris is floating around inside the hull(s). You'll have to navigate through this in the dark. Much of the interior woodwork will have come loose and be floating around with nails and/or screws sticking out of it - think swimming through barb wire! Cushions will be floating around blocking your way and your ability to see - very disorientating! You want an escape hatch right over/under your cabin(s) to make egress as easy as possible when it hits the fan. Trying to find/deploy breathing apparatus unless your train regularly for such an emergency will be a cluster flock. Even at six feet down, take a breath of compressed air, hold your breath and surface and you'll likely rupture your airway or lungs. Relying on emergency compressed air breathing apparatus' rather than a proper escape hatch is not a good idea!
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Old 04-06-2020, 08:45   #11
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Re: Mini scuba tanks instead of escape hatches?

Quote:
Originally Posted by toolbar View Post
Hi,


we also just bought a catamaran without escape hatches.



I plan to add them next winter, building them with sandwich laminate and not a standard see-through escape hatch.


I don't like the idea of using the small scuba tanks as a replacement. What if more than one person need to evacuate from a hull? Will you always make sure, they are filled and working?




Paul
So we're talking 'escape' hatches below the waterline in these multihulls? A monohull guy, I've sailed as guest/crew aboard 4 or 5 (bluewater-capable) catamarans. Two that I know of had escape hatches, and both captains complained of their leaking. One skipper was quite fearful of the hatch failing completely and flooding the boat, and apparently this is a legitimate concern.
I understand that everything would have to go just right for an emergency air tank to be used successfully, especially upside down in the dark, tangled up in stuff. But having a hole in the boat that I could crawl through, facing the bottom of the ocean, would not be conducive to a good nights sleep.
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Old 04-06-2020, 08:49   #12
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Re: Mini scuba tanks instead of escape hatches?

When I think of an inverted catamaran, and the requirement to evacuate a hull, I don't think of diving any substantial distance to escape the hull. Even assuming the hull is barely floating at the waterline (inverted), it would seem that the downward movement to escape would be in the range of 10 feet of depth (into the main saloon) and out the 'door'.

Now, the ability to do this under stress, with everything inverted, entangled, and in the dark, possibly with more than one person, is a whole other issue.

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Old 04-06-2020, 08:49   #13
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Re: Mini scuba tanks instead of escape hatches?

Hi. I should have added two additional references. DAN, the Divers Alert Network and UHMS, a network of physicians and professionals in hyperbaric medicine.
The dangers of compressed air even in shallow waters, are simply scientifically valid facts and apply to hooka as well.
There will be posters who will state they have used compressed air without formal training and certification. It is a personal choice. All I ask is that you seek professional advice. Witch doctors might be helpful in certain cultures, but I believe an medical degree should be at least equally respected.
This is not a debate on anchors or mono vs catamaran. Please consider the qualifications of the posters.
My greatest fear at sea is fire. I’m certified as a marine firefighter and went to a regular firefighting school. I now have a tremendous respect for firefighters because of what I learned. I’ve thought about spare air size tanks for an onboard fire fight. My personal decision was not to carry any half measure device which might tempt one to believe a few breaths can save your vessel from fire. Your original post asked a simple question and the answer is equally easy...seek professional advice.
Regards, Mark the manatee.
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Old 04-06-2020, 08:57   #14
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Re: Mini scuba tanks instead of escape hatches?

Any healthy person should be able to swim out of a capsized catamaran. At night, yes, you need a waterproof light which you should have in each hull anyway. I would think twice about leaving at night to begin with, what would be the goal ? A battery powered cutting device in each hull is something to consider for cutting an exit hole. A small air tank probably would work, at a very shallow depth you are not going experience normal diving dangers other than to never hold your breath when surfacing while using an air supply, you can burst your lungs. This rule does not apply to free diving without a tank or surface supply.
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Old 04-06-2020, 09:00   #15
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Re: Mini scuba tanks instead of escape hatches?

I flew the AH-64 over the Yellow Sea, we carried “HEEDS” bottles on the left side of our survival vests and of course trained with them, HEEDS is of course an acronym, it stands for Helicopter Emergency Egress Device something, it’s been twenty years so I forgot.
Anyway these HEEDS bottles are nothing more than what Scuba divers call spare air, they are widely available, and you should train with them and they are refillable just like a Scuba tank.
Google found the HEEDS bottle, it’s just a spare air, don’t waste your money on a helicopter price https://www.aviationsurvival.com/-HE...e-17_p_35.html
There are a few differences with them over regular diving, to begin with nothing covers your nose, normally a mask does of course, but without a mask water gets in your nose when you breathe and that takes some getting used to.
Then of course you cannot have an auto inflating life vest or a regular buoyant one as it would just pin you to the top of the boat.

The Spare air bottle should give you about 5 min of air at very shallow depths and 5 min is a very long time. A major problem with suddenly being flipped over in a helicopter and I assume a boat is disorientation, we were trained to keep our left hand attached to the hand hold and use that as a reference to where you are, many People in training in the Dunker in NAS Jax where we received our initial training would head the wrong way and further trap themselves.
After Retirement I started cave diving and learned some more things there.

If were to have a Cat I’d want a couple of spare air bottles mounted in an obvious location, but I’d also want a light, just a decent dive flashlight would be fine, and a thin line that would lead me to the way out, this line could be attached to the roof so it would be out of the way which would of course become the floor. With just a little training a line can really be calming and ensure your heading the right way.

In cave diving a guy named Forrest Wilson invented the line arrow, it’s just a plastic triangle that attaches to the line and of course always points the way out, before the line arrow there were some deaths where people got confused and went deeper into the cave thinking they were headed out.
https://www.diverite.com/products/reels/line-arrow/
Forrest is an old guy now but still dives or was when I stopped anyway.

If you go with a spare air bottle, you need to at least become accustomed to breathing one underwater, and it can be the middle of the night of course. I would be very comfortable with a spare air myself with a light and a line.
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