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23-12-2021, 19:56
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#16
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Registered User
Join Date: Jan 2014
Location: Miami Beach Fl
Boat: Colombia Cc 11.8
Posts: 1,758
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Re: Surface Air Supply (Hookah) Systems
I looked into this a while ago and pretty much all the compressors had enough pressure, the problem is finding a small oilless inexpensive 12 volt compressor with enough cubic feet per minute. Sorry I can't remember exactly what it is but I don't think 1.9 is enough.(that's what the compressor in the last link you showed has)
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23-12-2021, 20:24
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#17
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Registered User
Join Date: May 2010
Location: Sydney Australia
Boat: Fisher pilothouse sloop 32'
Posts: 3,416
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Re: Surface Air Supply (Hookah) Systems
Quote:
Originally Posted by sparrowhawk1
I looked into this a while ago and pretty much all the compressors had enough pressure, the problem is finding a small oilless inexpensive 12 volt compressor with enough cubic feet per minute. Sorry I can't remember exactly what it is but I don't think 1.9 is enough.(that's what the compressor in the last link you showed has)
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Agree wholeheartedly, the min free air capacity is I believe 3.5 cfm, and the compressor needs to have a 100% duty cycle. Finding a small 12 volt compressor to meet these demands can be challenging and not cheap. There are mains fed compressors that can be run through an inverter that can meet these requirements but once again not particularly cheap.
__________________
Rob aka Uncle Bob Sydney Australia.
Life is 10% the cards you are dealt, 90% how you play em
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23-12-2021, 21:03
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#18
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Hull Diver
Join Date: Oct 2006
Location: Under a boat, in a marina, in the San Francisco Bay
Posts: 5,428
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Re: Surface Air Supply (Hookah) Systems
Quote:
Originally Posted by sparrowhawk1
...the problem is finding a small oilless inexpensive 12 volt compressor with enough cubic feet per minute.
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As with most things, when it comes to air compressors cheap is not good and good is not cheap.
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24-12-2021, 07:00
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#19
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Registered User
Join Date: Jun 2008
Location: Tampa, FL
Posts: 5,009
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Re: Surface Air Supply (Hookah) Systems
An average human consumes between .75 and 1.0 cubic feet per minute of air at rest. Moderate activity will get that up to between 1.0 and 1.5 CFM. So, for just casual diving you probably want something that can deliver at least 1.5 CFM. For bottom cleaning I would guess you need a minimum of 2 CFM, and very possibly more than that.
The thing is, the deeper you go, the more air has to be pushed down from the surface to supply that amount. At about 33 feet down the pressure is double what it is on the surface. That means that to get 1.5 CFM of air at 33 feet you have to be pushing 3.0 CFM at the surface.
You can do the math from there to figure out how much air you will need for what you want to do.
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24-12-2021, 08:00
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#20
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Hull Diver
Join Date: Oct 2006
Location: Under a boat, in a marina, in the San Francisco Bay
Posts: 5,428
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Re: Surface Air Supply (Hookah) Systems
Quote:
Originally Posted by sparrowhawk1
...I don't think 1.9 is enough.
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The Thomas 1207PK80 is the current hull cleaning industry standard and I have used it for decades. It provides 1.99 CFM at 100 PSI and this is plenty for a hard-working diver at the depths typical of this job.
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24-12-2021, 16:28
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#21
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Registered User
Join Date: Jan 2014
Location: Miami Beach Fl
Boat: Colombia Cc 11.8
Posts: 1,758
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Re: Surface Air Supply (Hookah) Systems
Quote:
Originally Posted by fstbttms
The Thomas 1207PK80 is the current hull cleaning industry standard and I have used it for decades. It provides 1.99 CFM at 100 PSI and this is plenty for a hard-working diver at the depths typical of this job.
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how about if you want to be able to stay at 30 to 40 ft ? Thanks.
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24-12-2021, 16:37
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#22
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Hull Diver
Join Date: Oct 2006
Location: Under a boat, in a marina, in the San Francisco Bay
Posts: 5,428
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Re: Surface Air Supply (Hookah) Systems
Quote:
Originally Posted by sparrowhawk1
how about if you want to be able to stay at 30 to 40 ft ? Thanks.
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I wouldn't use a hookah at that depth for any length of time.
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24-12-2021, 17:05
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#23
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Registered User
Join Date: Aug 2019
Posts: 42
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Re: Surface Air Supply (Hookah) Systems
First, I don't trust eBay as far as I can throw them. I want to talk directly with the seller or there ain't no deal.
I picked up a REAL hooka system int he ~500 range, had it refurbished, got new hoses, regulator and it works GREAT. Hose is 40 ft so can cover most of the bottom, but don't use it much deeper than 20 ft. Couldn't be happier.
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24-12-2021, 18:54
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#24
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Registered User
Join Date: Dec 2014
Location: New Franklin, Ohio
Boat: Homebuilt schooner 64 ft. Sold.
Posts: 1,486
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Re: Surface Air Supply (Hookah) Systems
Quote:
Originally Posted by fstbttms
I wouldn't use a hookah at that depth for any length of time.
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Very true, those depths are starting to be in a zone a person needs to think about nitrogen buildup when staying for more than a few minutes. Consult the dive tables for nitrogen buildup, the cause of bends.
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24-12-2021, 18:58
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#25
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Registered User
Join Date: Oct 2010
Location: The boat - New Bern, NC, USA; Us - Kingsport, TN, USA
Boat: 1988 Pacific Seacraft 34
Posts: 1,454
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Re: Surface Air Supply (Hookah) Systems
Quote:
Originally Posted by fstbttms
The Thomas 1207PK80 is the current hull cleaning industry standard and I have used it for decades. It provides 1.99 CFM at 100 PSI and this is plenty for a hard-working diver at the depths typical of this job.
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That compressor is a 125V model. What would be a suitable 12V model?
Why is a 100 psi compressor and a secondary regulator rated for a 80-110 psi air supply needed for hull cleaning to a depth of maybe 8 ft? To me it looks like a waste of energy to compress air to 6 bar in order to breath it at 0.3 bar. Sure there is some pressure lost in the hose, regulator, and all; but loosing 5.7 bar between the compressor outlet and the mouth seems like a lot of waste (and a lot of heat to lose as well).
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24-12-2021, 19:03
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#26
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Registered User
Join Date: Dec 2014
Location: New Franklin, Ohio
Boat: Homebuilt schooner 64 ft. Sold.
Posts: 1,486
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Re: Surface Air Supply (Hookah) Systems
Quote:
Originally Posted by wsmurdoch
That compressor is a 125V model. What would be a suitable 12V model?
Why is a 100 psi compressor and a secondary regulator rated for a 80-110 psi air supply needed for hull cleaning to a depth of maybe 8 ft? To me it looks like a waste of energy to compress air to 6 bar in order to breath it at 0.3 bar. Sure there is some pressure lost in the hose, regulator, and all; but loosing 5.7 bar between the compressor outlet and the mouth seems like a lot of waste (and a lot of heat to lose as well).
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I don’t think you are looking at the phisologiccal effects that pressure has on the body itself. There are other aspects to look at besides compressor limitations.
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24-12-2021, 19:13
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#27
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Registered User
Join Date: Oct 2010
Location: The boat - New Bern, NC, USA; Us - Kingsport, TN, USA
Boat: 1988 Pacific Seacraft 34
Posts: 1,454
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Re: Surface Air Supply (Hookah) Systems
Quote:
Originally Posted by captlloyd
I don’t think you are looking at the phisologiccal effects that pressure has on the body itself. There are other aspects to look at besides compressor limitations.
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I don't understand. At 8 ft down cleaning a hull the pressure is about 4 psi. Why do we compress the air to 100 psi and use a regulator rated at 80-110 psi to supply a diver working at that depth with 4 psi air. We are wasting 96 psi. The compressor is doing unnecessary work, heating the air unnecessarily, and using more electricity than necessary.
I have never used a hookah, and honestly want to understand.
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24-12-2021, 19:38
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#28
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Registered User
Join Date: Dec 2014
Location: New Franklin, Ohio
Boat: Homebuilt schooner 64 ft. Sold.
Posts: 1,486
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Re: Surface Air Supply (Hookah) Systems
Quote:
Originally Posted by wsmurdoch
I don't understand. At 8 ft down cleaning a hull the pressure is about 4 psi. Why do we compress the air to 100 psi and use a regulator rated at 80-110 psi to supply a diver working at that depth with 4 psi air. We are wasting 96 psi. The compressor is doing unnecessary work, heating the air unnecessarily, and using more electricity than necessary.
I have never used a hookah, and honestly want to understand.
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I believe at 13 feet the pressure on the body is twice that at sea level atmospheric pressure. Try submerging a beach ball down to 8 feet and see what happens to the ball. More pressure will be required for the ball to be returned to its blown up size as it has been squeezed down considerably. This is also the reason why you NEVER hold your breath when surfacing while using surface supplied air !! Your lungs can rupture. All the more reason to at the very least, buy an instructional book on diving so you can at least understand the basics. And I say this for folks intending on cleaning their boat bottoms and maintenance. All others intending on going deeper need to get some professional instruction.
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24-12-2021, 19:55
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#29
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Registered User
Join Date: Mar 2018
Location: www.mvmojo.com
Boat: Robt Beebe Passagemaker 49-10 in steel
Posts: 424
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Re: Surface Air Supply (Hookah) Systems
Quote:
Originally Posted by Frankly
If you happen to have an onboard diving tank (good for a lot of reasons) then you can buy a long hose to go between the first and second stages of your breathing regulator. Brownie makes a slick setup with some quick disconnect connectors. I have been using one to change props/ clean boat bottom for 25 years.
Frankly
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If you're a certified diver and can get tank refills, this is my recommendation. We used a tank on deck with a 50' hose for over 25 years. Very simple and very effective. If you're not a certified diver, get certified! Breathing compressed air underwater, even at 6-8' at depth and not knowing what you're doing is a recipe for disaster...
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24-12-2021, 20:03
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#30
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Senior Cruiser
Join Date: Oct 2007
Location: 29° 49.16’ N 82° 25.82’ W
Boat: Pearson 422
Posts: 16,306
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Re: Surface Air Supply (Hookah) Systems
Quote:
Originally Posted by captlloyd
Very true, those depths are starting to be in a zone a person needs to think about nitrogen buildup when staying for more than a few minutes. Consult the dive tables for nitrogen buildup, the cause of bends.
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You would have to spend a lot more than a few minutes at 30-40' to incur a deco obligation or risk of the bends. More like two or three hours.
The bigger risk to an untrained diver would be barotrauma.
Also pressure doubles at 32' not 13'.
__________________
The water is always bluer on the other side of the ocean.
Sometimes it's necessary to state the obvious for the benefit of the oblivious.
Rust is the poor man's Loctite.
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