[PSUBS-MAILIST] onboard gear

Wed Apr 24 16:02:46 EDT 2019

 Alan. I am not talking a permanent buoy line. I mean a spool with float that is released in an emergency Hank
    On Wednesday, April 24, 2019, 1:45:42 PM MDT, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  

 Hank,I think putting a strong line on your sub may be more of a danger than a benefit. If you were dragging it with a float it may get caught in an underwatertree or structure. Or if it came loose it could tangle.That is why, apart from the size, I am planning on using a 150lb braid. At leastI could break free.Alan
On 24/04/2019, at 10:08 PM, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

 Wow, looks like Kevlar rope has come way down in price.  For 1500 dollars you can have a 600 foot rope that has a tensile strength of 9500 lbs.    Hank
    On Wednesday, April 24, 2019, 3:58:52 AM MDT, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  

  I built my escape pod because I am pretty darn sure I would not survive a emergency bail out.  I am not a diver and can't really swim either.  The escape pod is only good for one person and is not tested.  A good friend is always nagging at me to put a Kevlar buoy line on Gamma strong enough to lift the sub even full of water.  I always argue cost and will the rope be strong enough to overcome the entanglement.  I think we figured it would cost 5K but maybe it would be well worth it.  In my case it would make sense because I already have a lifting barge capable of lifting 6,000 lbs with its centre mounted winch.  the barge is even portable with no permits.  I would like to hear ideas around this idea.  I would be willing to do this unless there is something I am missing?Hank
    On Wednesday, April 24, 2019, 12:22:30 AM MDT, Douglas Suhr via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  

 I do not speak with the same authority as Steve (being an experienced technical diver and all) but in my own opinion, the idea of bailing out of a sub at ANY depth seems crazy. In my own mind, I've always likened U/W escape to wearing a parachute while flying in an airplane. Yes, theoretically in some situations it will save you, but practically speaking it seems like more of a false sense of security than a practical solution for survival. Then again, if your situation is so dire that you're about to die anyway, might as well give it a shot. Personally, I would rather believe someone on the surface is going to be able to perform a rescue with lift bags where I can get back to the surface dry. ~ Doug 
On Wed, Apr 24, 2019 at 12:13 AM Stephen Fordyce via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Hi all,This is an interesting discussion I've been meaning to weigh in on - as an experienced tech/deep/cave diver rather than a sub person.
My feel is that unless the escapee is an experienced diver (and even then), the chances of a successful escape from below 50m/150ft depth are so low as to be almost negligible. And I'd suggest having a plan for such is (almost) an entirely false sense of security - and energy should be diverted elsewhere to reduce risk.
A few of the scarier things like narcosis and the bends have had a lot of airtime, but basic stuff like keeping a diving mask clear (and one that's probably fogging up), panic-breathing a soggy SCUBA reg and dealing with the thermal shock of sudden immersion are likely to cause death by drowning much earlier. Don't underestimate the thermal shock and how useless it makes you with no exposure suit. Breathing a regulator without a mask is a skill in itself. You're probably already suffering from fatigue, stress, high CO2 and/or low O2 from waiting for rescue and getting to such a desperate point. All of these cause significant mental impairment before you even start on the escape.
Forget about planning to hold stops on the way up, switch gases or do decompression. Even if you're lucky enough to still be conscious and thinking in the latter stages of the rapid ascent, personal buoyancy control is unlikely to be possible.
So if you're going to attempt to escape, I suggest the best chance for survival is to plan on a very simple setup (per person), buoyancy for a rapid/undignified ascent, and needing urgent medical attention and oxygen on the surface.  Maybe carry a cylinder of trimix on board to give yourself a better chance of being able to think, but it's a big weight/cost premium if it's enough to be useful.  Use a divers (with closed bottom) "lift bag" and a loop around at the armpits as a quick and easy way to get a person shooting upwards. CO2 inflatable life jacket to keep unconscious head above water on surface. (Inflate at depth while conscious - won't fill much, but will expand on way up) Might be better put towards things like extra life support duration.  Consider doing regular practise drills that are as realistic as possible.
Highly skilled divers mess up basic skills in stressful situations and die with sad regularity. Don't imagine your (and passengers) chances of winging it at depth will be anything other than tiny. 30m/90ft and shallower they are a bit better.
I hate to be negative, but perhaps for deep PSUB diving, the inability to escape is just one of those residual risks that can be accepted for a recreational activity.
Cheers,Steve Fordyce Melbourne, Australia
On Wed, 24 Apr 2019 10:57 hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

 I think all submarines should have an escape pod or jettisoning occupant sphere.  I admit I made a mistake with my escape pod by making it only for one.  An easy fix that I will likely tackle, and that is to stretch the pod making it big enough for two.  E3000 has a jettisoning occupant sphere.Hank
    On Tuesday, April 23, 2019, 5:39:01 PM MDT, TOM WHENT via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  

 A compact bail out rebreather might be the most surviveable solution however it would require a significant commitment in training, maintenance as well as the cost of the equipment itself. I personally have not been following the development of bailout rebreathers, although i'm aware that some are working on this. My dive group relies on planning for open circuit bailout in the event of rebreather failure. 

If money is no object, I am partial to the ISC Megalodon classic CCR. In terms of robustness and deep water capability,  you will find none better. 
It will get you home and flies itself. It is an electronic CCR which maintains PPO2 for the user. This is the unit I dive myself and feel very confident in. 

KISS classics, which are a simple and reliable mechanical CCR apparatus, often come up on the used market in affordable price ranges. 

Both would require significant equipment specific training but would get you out of a 400 ft jam with only two small cylinders and gas to spare. CCR duration is driven by metabolic rate and is the same irrespective of operational depth. Even the lowest end units will give you an hour plus. 

On ascent, rebreathers do require the diver to be monitoring the oxygen level display in the breathing loop and very likely adding oxygen manually - particularly in the mCCR type on a fast ascent.
The other benefit of this setup is that an air cell for buoyancy can be integrated easily in one compact package. 

It sounds like a lot of effort for the non diver, but it is a functional answer to the risks of a sub disabled in deep water. 
What is a life worth? 
How much risk can one accept for a hobby? 

Food for thought anyhow. 

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On Tue, Apr 23, 2019 at 7:34 PM -0400, "Alan via Personal_Submersibles" <personal_submersibles at psubs.org> wrote:

As an alternative to possible death or even worse, the loss of your submarine,I am in early stages of designing a buoy release mechanism that is usedfor surfacing safely but has an emergency beacon that can be activated with an electro magnet.Thoughts are to use 150 lb braid with a tensioning mechanism & have anautomatic boat latch mechanism that can slide down the braid but is fixedto the buoy with instructions, "tie a long rope to the ring & let down untilllatch attaches to submarine. Pull up"The automatic latch is a device that Phil described & provided a drawing for,but there may be a cheap & suitable automatic boat latch ( used on release& retrieve on boat launching) on the market. I am still searching & if anyoneknows of one that may be suitable I would be interested.Alan
On 24/04/2019, at 10:51 AM, Sean T. Stevenson via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

There is a significant difference between submarine escape and a planned SCUBA dive with regard to both the dive profile and the equipment that you can reasonably carry.  An escape is more akin to what is known as a buoyant emergency ascent in recreational diving, where you need to get to the surface yesterday and all other considerations are secondary.  In this specific case, trying to keep to a slow ascent rate would significantly increase the incurred decompression obligation that you must necessarily then blow off as you ascend through the shallows, introducing an even greater risk.  You also have the hypothermia issue to deal with if you are not equipped with exposure protection specifically intended for submersion at depth. Being cold reduces decompression effectiveness. In order to keep to a target ascent rate or perform decompression stops, you would need diving instrumentation (depth gauge and timer), would need the skills and experience to perform gas switches and hold stops, and would need significantly more bulky equipment to have enough gas to perform a proper decompression (slow ascent, gas switches, etc.).

When I dive to these depths on SCUBA, I wear twin cylinders (>100 cu. ft. each) on my back with the bottom gas (10/70 or whatever for the planned depth and time), plus three or four off-board cylinders (80s) carrying the decompression gases (typically 21/35, 35/25, EAN50 and oxygen), plus a small bottle of argon for drysuit inflation.  Obviously, as an escapee you are not so equipped.  Far better to lockout as quickly as possible and rapidly ascend (with buoyant assist) to get clear of those depths where you are ongassing the most, and if at all possible, to slow the ascent as you approach the surface, and then have your surface support or emergency responders administer oxygen as transport is arranged to recompression.  To be clear, an emergency escape from a disabled submarine at these depths is not even remotely a good idea - it is simply a marginally better idea than dying on the bottom.

To illustrate, if you were to attempt a continuous ascent from 300 fsw, the average depth is 150 fsw, which is about 5.5 atmospheres absolute.  If you assume a surface air consumption rate of 1 cu. ft. / minute (high, but typical of a diver who is stressed or working hard, which is inevitable in a submarine escape scenario), that corresponds to 5.5 cu. ft. / min at the average depth of the ascent.  At a 30 ft/min ascent rate, that's 10 minutes, or 55 cu. ft. of gas consumed just for the continuous ascent with no decompression stops, without consideration for the gas consumed while blowing down and locking out.  You can judge for yourself the practicality of carrying an 80 on a PSub sized vessel just for emergency escape purposes.

Sean

‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
 On Tuesday, April 23, 2019 12:32 PM, David Colombo via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Hi Guys, This topic is fascinating and scary at the same time. Accent rates form the old Navy logs had 60ft / minute max with a recommended max accent rate of 30 ft/ min. At 300ft escape depth, what volume of mixed gases would you need for a 10 minute accent assuming you choose not to swim 60ft/min.

Best Regards,
David Colombo

804 College Ave
Santa Rosa, CA. 95404
(707) 536-1424
www.SeaQuestor.com

_______________________________________________
Personal_Submersibles mailing list
Personal_Submersibles at psubs.org
http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles

As an alternative to possible death or even worse, the loss of your submarine,I am in early stages of designing a buoy release mechanism that is usedfor surfacing safely but has an emergency beacon that can be activated with an electro magnet.Thoughts are to use 150 lb braid with a tensioning mechanism & have anautomatic boat latch mechanism that can slide down the braid but is fixedto the buoy with instructions, "tie a long rope to the ring & let down untilllatch attaches to submarine. Pull up"The automatic latch is a device that Phil described & provided a drawing for,but there may be a cheap & suitable automatic boat latch ( used on release& retrieve on boat launching) on the market. I am still searching & if anyoneknows of one that may be suitable I would be interested.Alan
On 24/04/2019, at 10:51 AM, Sean T. Stevenson via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

There is a significant difference between submarine escape and a planned SCUBA dive with regard to both the dive profile and the equipment that you can reasonably carry.  An escape is more akin to what is known as a buoyant emergency ascent in recreational diving, where you need to get to the surface yesterday and all other considerations are secondary.  In this specific case, trying to keep to a slow ascent rate would significantly increase the incurred decompression obligation that you must necessarily then blow off as you ascend through the shallows, introducing an even greater risk.  You also have the hypothermia issue to deal with if you are not equipped with exposure protection specifically intended for submersion at depth. Being cold reduces decompression effectiveness. In order to keep to a target ascent rate or perform decompression stops, you would need diving instrumentation (depth gauge and timer), would need the skills and experience to perform gas switches and hold stops, and would need significantly more bulky equipment to have enough gas to perform a proper decompression (slow ascent, gas switches, etc.).

When I dive to these depths on SCUBA, I wear twin cylinders (>100 cu. ft. each) on my back with the bottom gas (10/70 or whatever for the planned depth and time), plus three or four off-board cylinders (80s) carrying the decompression gases (typically 21/35, 35/25, EAN50 and oxygen), plus a small bottle of argon for drysuit inflation.  Obviously, as an escapee you are not so equipped.  Far better to lockout as quickly as possible and rapidly ascend (with buoyant assist) to get clear of those depths where you are ongassing the most, and if at all possible, to slow the ascent as you approach the surface, and then have your surface support or emergency responders administer oxygen as transport is arranged to recompression.  To be clear, an emergency escape from a disabled submarine at these depths is not even remotely a good idea - it is simply a marginally better idea than dying on the bottom.

To illustrate, if you were to attempt a continuous ascent from 300 fsw, the average depth is 150 fsw, which is about 5.5 atmospheres absolute.  If you assume a surface air consumption rate of 1 cu. ft. / minute (high, but typical of a diver who is stressed or working hard, which is inevitable in a submarine escape scenario), that corresponds to 5.5 cu. ft. / min at the average depth of the ascent.  At a 30 ft/min ascent rate, that's 10 minutes, or 55 cu. ft. of gas consumed just for the continuous ascent with no decompression stops, without consideration for the gas consumed while blowing down and locking out.  You can judge for yourself the practicality of carrying an 80 on a PSub sized vessel just for emergency escape purposes.

Sean

‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
 On Tuesday, April 23, 2019 12:32 PM, David Colombo via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Hi Guys, This topic is fascinating and scary at the same time. Accent rates form the old Navy logs had 60ft / minute max with a recommended max accent rate of 30 ft/ min. At 300ft escape depth, what volume of mixed gases would you need for a 10 minute accent assuming you choose not to swim 60ft/min.

Best Regards,
David Colombo

804 College Ave
Santa Rosa, CA. 95404
(707) 536-1424
www.SeaQuestor.com

_______________________________________________
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Personal_Submersibles at psubs.org
http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles

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