Kingshorn from shore
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Hi All,
On a nice sunny day in August, diving off of a boat, this dive offers no more difficulty than any other wreck in 90' of water. When you start adding environmental factors such as a 700' swim each way, overhead ice and 32 degree water this turns into a dive that can kill you as quickly as you please if you are not trained for it and do not have the right equipment.
The main problem as I see it is two fold. One is a matter of perception. There are any number of people that do this dive on a regular basis, not only the guys and gals from NTD. To a relatively inexperienced diver we make this seem easy and talk about it in different terms that a new diver has a reference for. For example I can talk to another diver such as Matt from Dans Dive and he automatically understands the degree of difficulty and danger involved in this particular dive. When I say to Matt 'we did and easy swim out the Kinghorn' at this time of year he will understand that degree of difficulty is relative. What is easy for me as a technical diver is likely beyond the comprehension of a less experienced diver yet it it viewed as easy to all just by the way we talk about it as a general diving activity. As Artw so honestly admitted that this was his perception and reality turned out to be a different thing altogether.
Secondly most divers tend to vastly over-estimate their skill and ability. This unfortunately has led to a number of untimely deaths in our sport. We have divers still doing air to 240' on the wall in 32 degree water chasing a computer for deco that does not take into account temperature in it's model. Is this smart? No not at all. Most will agree now that this is Darwinian behavior at its best. In all honesty I was guilty of this style of diving five or six years ago until I came to the same spot that artw was at on the Kingshorn. At 240', on air, narc'd out of my gourd and had a CO2 hit to boot. I realized then that the clock was ticking and it was only a matter of time before I killed myself if I continued diving that way. Since have seen the light so to speak. The point is I did not know how dangerous the things that I was doing were until confronted with an episode that was scary enough to wake me up. I know many divers that are still in the invincible phase of their diving careers. I can honestly say that I believe that the only reason I am here today is that I did not have any emergencies to deal with when I was doing stupid things.
I do dives like the Kingshorn not for bragging rights but because it is a dive that I can do in the winter time that is within my skill level that I can use to keep my skills sharp during the winter. It is a training dive because it combines and exercises all the facets of my ability except for one and that is depth. This is another limitation that I do not cross in the winter and that is decompression. I limit my time in water to 60 minutes max so that minimum decompression is required. (Minimum deco is 1's to the exit point). No deco models take into account severely cold water so having a computer trying to calculate it or guessing yourself you are just urinating into the wind.
As to Arts question as to whether or not he can do this safely in a single tank. First off if trying this from shore means it is a thirds dive. If you have open water then in an emergency you can ascend in the middle of any boats that are zipping around so this is not a planned option therefore we have to plan to get back to shore after a tour of the wreck. The average depth on the dive is around 70'(21m) or ~3ATA. Assuming a swim rate of 75'/minute it will take about 10 minutes to get to the wreck. We want to spend at least 20 minutes on the wreck and then an additional 10 to get back. That gives a total of 40 minutes at 3ATAs time an average SAC of .7cf/minute which equals 84cf just for you. If you encounter a problem on the worst part of the wreck, the stern in this case, it would take about five minutes to deal with the OOA situation and make it back to the line then 10 minutes more to make it home. So this would require 15 minutes of gas x 2 divers x 3 ATAs with an SAC of 1.0 (emergency) for a total of an additional 90cf of gas required. This means you need to start with 174cf of gas. If you could pump a 104 or E130 to 4450 psi that would do the job. Not really possible though.
So you can make up your own mind but in my opinion this is a dive that should only be done with doubles. If you limit your time to 15 minutes on the wreck you could manage with 80's. Carrying extra bottles unless you are trained how to properly use them and what to do in the event of an emergency could be more distracting than helpful. So can it be done on a single? Yes it can. Can it be done safely on a single? You decide.
The year before last I saw divers diving on the Jodrey with single AL80's on air. This is likely the most dangerous dive in the whole area but I bet that they thought that they were 'safe'.
On a nice sunny day in August, diving off of a boat, this dive offers no more difficulty than any other wreck in 90' of water. When you start adding environmental factors such as a 700' swim each way, overhead ice and 32 degree water this turns into a dive that can kill you as quickly as you please if you are not trained for it and do not have the right equipment.
The main problem as I see it is two fold. One is a matter of perception. There are any number of people that do this dive on a regular basis, not only the guys and gals from NTD. To a relatively inexperienced diver we make this seem easy and talk about it in different terms that a new diver has a reference for. For example I can talk to another diver such as Matt from Dans Dive and he automatically understands the degree of difficulty and danger involved in this particular dive. When I say to Matt 'we did and easy swim out the Kinghorn' at this time of year he will understand that degree of difficulty is relative. What is easy for me as a technical diver is likely beyond the comprehension of a less experienced diver yet it it viewed as easy to all just by the way we talk about it as a general diving activity. As Artw so honestly admitted that this was his perception and reality turned out to be a different thing altogether.
Secondly most divers tend to vastly over-estimate their skill and ability. This unfortunately has led to a number of untimely deaths in our sport. We have divers still doing air to 240' on the wall in 32 degree water chasing a computer for deco that does not take into account temperature in it's model. Is this smart? No not at all. Most will agree now that this is Darwinian behavior at its best. In all honesty I was guilty of this style of diving five or six years ago until I came to the same spot that artw was at on the Kingshorn. At 240', on air, narc'd out of my gourd and had a CO2 hit to boot. I realized then that the clock was ticking and it was only a matter of time before I killed myself if I continued diving that way. Since have seen the light so to speak. The point is I did not know how dangerous the things that I was doing were until confronted with an episode that was scary enough to wake me up. I know many divers that are still in the invincible phase of their diving careers. I can honestly say that I believe that the only reason I am here today is that I did not have any emergencies to deal with when I was doing stupid things.
I do dives like the Kingshorn not for bragging rights but because it is a dive that I can do in the winter time that is within my skill level that I can use to keep my skills sharp during the winter. It is a training dive because it combines and exercises all the facets of my ability except for one and that is depth. This is another limitation that I do not cross in the winter and that is decompression. I limit my time in water to 60 minutes max so that minimum decompression is required. (Minimum deco is 1's to the exit point). No deco models take into account severely cold water so having a computer trying to calculate it or guessing yourself you are just urinating into the wind.
As to Arts question as to whether or not he can do this safely in a single tank. First off if trying this from shore means it is a thirds dive. If you have open water then in an emergency you can ascend in the middle of any boats that are zipping around so this is not a planned option therefore we have to plan to get back to shore after a tour of the wreck. The average depth on the dive is around 70'(21m) or ~3ATA. Assuming a swim rate of 75'/minute it will take about 10 minutes to get to the wreck. We want to spend at least 20 minutes on the wreck and then an additional 10 to get back. That gives a total of 40 minutes at 3ATAs time an average SAC of .7cf/minute which equals 84cf just for you. If you encounter a problem on the worst part of the wreck, the stern in this case, it would take about five minutes to deal with the OOA situation and make it back to the line then 10 minutes more to make it home. So this would require 15 minutes of gas x 2 divers x 3 ATAs with an SAC of 1.0 (emergency) for a total of an additional 90cf of gas required. This means you need to start with 174cf of gas. If you could pump a 104 or E130 to 4450 psi that would do the job. Not really possible though.
So you can make up your own mind but in my opinion this is a dive that should only be done with doubles. If you limit your time to 15 minutes on the wreck you could manage with 80's. Carrying extra bottles unless you are trained how to properly use them and what to do in the event of an emergency could be more distracting than helpful. So can it be done on a single? Yes it can. Can it be done safely on a single? You decide.
The year before last I saw divers diving on the Jodrey with single AL80's on air. This is likely the most dangerous dive in the whole area but I bet that they thought that they were 'safe'.
teamplayer:
Teamplayer,
Keep asking your questions. I do not believe that you have missed anything. There are some folks here that will answer you questions if you ask them loud enough and long enough.
artw
Guest
Dan,
Assuming equal current each way, and dive team members have similar SAC's and same tank capacities - would one be able to do the dive on thirds and turn when someone hits their 1/3?
Regardless, I do not have the training required to do this type of dive even if there is no ice.
Assuming equal current each way, and dive team members have similar SAC's and same tank capacities - would one be able to do the dive on thirds and turn when someone hits their 1/3?
Regardless, I do not have the training required to do this type of dive even if there is no ice.
FreeFloat
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artw... Dan already answered your question. See post #42 and para #5 where he explains the gas planning necessary. The only thing the SAC rate does is potentially shorten your dive as the buddy in your group with the highest rate, is gonna hit turn pressure first - might be on the way out, might be on the wreck, etc.artw:
FreeFloat
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PS You wouldn't find me on that wreck (from shore) with a steel 72... fat lotta good my SAC rate will do some 6' Hoover in an emergency.
JamesP
Contributor
FreeFloat:
I believe you just called me a vacuum cleaner!!!
artw
Guest
FF,
Perhaps I am misunderstanding the meaning of Thirds but as far as I know, once you or your buddy reach your first third you turn the dive, and from that point you are pretty much giving the last third in your tank to your buddy so you and them can get out, regardless of where you are in the dive
I would think turn pressure would take precedence over time spent on the wreck.
Perhaps I am misunderstanding the meaning of Thirds but as far as I know, once you or your buddy reach your first third you turn the dive, and from that point you are pretty much giving the last third in your tank to your buddy so you and them can get out, regardless of where you are in the dive
I would think turn pressure would take precedence over time spent on the wreck.
Hi Artw,artw:
The gas plan on this dive is a little different. You could indeed do as you suggested and turn on thirds. Once the dive is thumbed you head back for to the line and head in. In this case it would be the most conservative and thus safest way to do this dive. Just a quick example. If I have 104's pumped to 3000PSI (200BAR). This gives me 240cf (6400FL) of back gas. My turn pressure on thirds would be 2000psi (132BAR) and I would consume 80CF (2100fl). If it only takes me at best 10 minutes to get to the wreck at an average ATA of ~3 (3.4 actual) then I would use 3 x 10 x .5 = 15cf (495fl) on the way out. That leaves me with 65cf(1650FL) to play around with on the wreck or approximately 30 minutes. If I turned as soon as I hit thirds from anywhere on the wreck it would take no more than 5 minutes to get back to the line and come home for a total of 15 minutes (5 + 10) or 15 x 3ATA x .5 = 22cf (704fl) to get back. This should have me on shore with 138cf(4416fl) of gas left or 1700psi (112BAR).
The above gas volumes would be in a perfect world. I reality this is the sort of dive that I have done many times and depending on the current and temperature I usually have around 1400psi left. The missing 300psi can be explained by the time spent on the wreck which skews the average ATA to around 3.5.
Thirds had it's genesis in cave country where it is mostly related to distance and time. You go in a third, turn and come out. This strategy does not work particularly well for wreck/decompression dives. For the most part the only thing that makes it work in caves is that there is for the most part flow aiding you on the way out. It is as well based on the premiss that it takes no time to solve a problem and we can exit at the same pace we went in. If we did follow true thirds in a cave and had an OOA emergency at the exact time we turned on thirds it would be unlikely that we would make it out. Just a single minute to solve the problem, get sorted out, and get underway and the increased breathing, slower pace would leave us shy of the cavern. There are any number of examples of deaths of divers ending up a couple of hundred feet from their stages or cave exit. I am not saying it is a bad management tool it is just not as conservative as everyone thinks. It works in most cases it the best that can be said.
As a tech diver doing a dive with a considerable decompression obligation, say 25 minutes at 220' would give 60 of raw deco + deep stops. If we have an emergency on the bottom towards the tail end of the dive I need enough gas to get me and my buddy to the gas switch. My ascent would be as follows:
220' - 1 minute to manage the emergency
220' - 190' - 1 minute
190' - 170' - 1 minute
170' - 1 minute
160' - 1 minute
150' - 1 minute
140' - 1 minute
130' - 1 minute
120' - 2 minutes
110' - 2 minutes
100' - 2 minutes
90' - 2 minutes
80' - 2 minutes
70' -1 minute for the gas switch
So in total I need 19 minutes of gas x 2 divers = 38 minutes at an average ATA of 4.6 (round to 5) or 190cf (6000fl) of reserve gas just to do this dive safely! So clearly thirds does not work here. We do have a couple of strategies that we can employ that makes this a doable dive. On is that we can carry a 120' deco bottle of 30/30. This would lower our reserve obligation to 18 minutes of gas @ 6 ATA = 108cf (3500fl) which puts us in the ball park. Or even better is to carry an stage of 15/55 bottom gas and ditch it when it is empty then go on back gas.
I know that this is a very long winded answer to your question Artw but I just want to highlight to you that on the surface that something that logically makes superficial sense does not always make sense. Look a little deeper specially when you are doing contingency planning and you will find whether a certain gas plan suits the dive you are doing or not. Using the strategy that I outlined above even in a worst case scenario there is no real emergency, just business as usual. There is no need to blow off any stops just to get to the next gas switch or in the very worst case blow directly to the surface which has happened on far too many occasions usually resulting in a baratrauma/embolism/death.
heheheh
I knew there was a reason I had a second set of 104's!!
Maybe I should just "sling" the 2nd set.
Either that or invent a "Double Tank Adapter" (DTA) which would fit my 2nd set onto my 1st set............Call me Maffatone......(Or whatever the spelling is)
Well, when you need gas and you don't have any, I would have to agree.
I knew there was a reason I had a second set of 104's!!
Maybe I should just "sling" the 2nd set.
Either that or invent a "Double Tank Adapter" (DTA) which would fit my 2nd set onto my 1st set............Call me Maffatone......(Or whatever the spelling is)
Well, when you need gas and you don't have any, I would have to agree.
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