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Hi Everyone, This is going to be a rather muddled post, as I have been cut off for a long time due to the problems with the server. Please excuse me if these all look like they are very old threads, they are!! First cab off the rank is Big lights; I've had a lot of success building lights using PVC 'pressure pipe' and fittings. I have found that the weak point of any light housing is the port you have to open when you need to recharge the battery. Now I use a couple of small stainless bolts which penetrate the housing. They are easy to seal and are electrically connected to the battery inside. That is there is to say that there is one bolt per battery terminal. I have put a diode in line with the charging wire. This prevents damage if I hook up the charger backwards and more importantly, prevents discharge through the seawater.The result is that I almost never have to get into the battery housing. Instead of a complex arrangement of screws, locks and o-rings, I have a flat port that I silicone on over a hole in the end of the pipe. The pressure holds it on underwater, and if I ever need to get in, I just pry it off. So far I've only needed to do this once. That was when a colony of antsdecided to burrow into the silicone and set up house in the torch!!!! If you keep your dive gear away from ants you may never need to open thetorch!! Beware of sparks inside the torch as over charging gel cells can produce explosive gasses, best to seal the switch into a separate compartment away from the batteries. Next is counterdiffusion; On the 24th of Oct Andrew Pitkin wrote: > 1.Fast (helium) to slow (nitrogen) is good (especially on ascent) While this is true in terms of breathing gas, and whole body decompression, there is also the case where Helium mixture has been introduced into the ear during decent. It has been observed that on a gas switch from helium to nitrogen based mixture during ascent that this helium has counterdiffused across the inner ear, causing bubbles in the organs of balance. This condition is a problem because it may cause the diver to vomit underwater, and due to the poor blood supply to the area, it is *very* difficult to treat. Usually needing recompression to 30m below the dive depth. (well beyond most treatment chambers). Symptoms occur within seconds of making the gas switch and are characterised by a sensation of spinning or tumbling. It is one of the main reasons that commercial operators are reluctant to use surface oriented gas diving. Next; There has been some interest expressed in my on going talks with Prince Henry Hospital. (Sydney's local Hyperbaric unit is operated by the hospital) I reproduce here in full the first communication I have received from them since April: (THE PRINCE HENRY HOSPITAL *letterhead*) 24 October 1994 Mr Jason Rogers 61 Wellington Street BONDI NSW 2026 Dear Mr Rogers Since the time you came out to see us on the 22nd of April 1994 and together with the letters you have sent to us, I can assure you that Professor Torda, Dr Mike Bennett and Dr Martin Gleeson have very carefully looked at and thought about what you have had to say. We are all sure that you strongly desire to help us improve our service and we are taking steps to constantly do this. Should you wish to come out and see us again please do so. We would be able to give you an update on things and in particular the plans to relocate the chamber to the Randwick Campus as a part of the major redevelopment of that site. The chamber will be housed in a purpose built area as a part of the new buildings at Randwick. Yours sincerely (SIGNATURE) Dr R L Hockin Medical Superintendent You will have to draw your own conclusions regarding the tone of our discussions. If you would like to find out more on this subject you should contact Dr Hockin. He will have copies of my letters and if *he* would like to distribute them I would be most pleased. Changing subjects again, Someone, quite some time ago, (sorry I can't find the reference) suggested that the high DCI rates I had mentioned in another post was due to my misdiagnosing natural sleepiness as DCI. They pointed out that after all the stress and long boat ride anyone would be tired and that could well be the cause. As a commercial diver I have been in the situation of doing a 23 hour working day. Most of the day was spent balancing on a metal plank over a raging surf. Pouring rain, howling wind, and handling 250cuft cylinders, heavy tools, and carrying compressors. Four hours under water, in zero vis, pulling cables, wielding a 6 inch dredge, and flogging up bolts on a 12 foot diameter pipe section, while fighting surge and a boss who was angry at the delay. Over 100 men where standing around waiting for us to finish, and they were on double time and a half overtime. After that day I was *less* tired than after a 15 minute dive spent floating around a wreck in 260 ft of water. The boat ride was 25 minutes and I'd had 10 hours sleep the night before. I don't think the stress or work load is comparable. Lastly, (bet you thought I'd never finish) This sounds like a flame of Jody but I've seen similar things said by other table writers! on the 3rd of October Jody Svendsen of MIG wrote; Certainly, MiG Plan uses an unmodified Buhlmann algorithm, so all of the testing used to validate his tables applies also to MiG Plan. You could also say that the experience with his published tables, and to a lesser extent the experience with the Aladin Pro computer (it's a slightly different and more conservative model) is also valid for MiG Plan. And then in his next post, on the same day, wrote; Just wanted to clear up this up. To the best of our knowledge, nobody has ever been bent on MiG Plan. If anyone out there is aware of a case, please let us know; we would obviously be very interested. (end quote) If you take these statements together a very disturbing attitude is apparent. An attitude that is not only Jody's, but is shared by a lot of table producers. On one hand he has said he doesn't need to test his tables, the Swiss have done all that work for him. (He strongly *associates* his tables with the Swiss tables). Then goes on to say that he has never heard of DCI with his tables (He strongly *dissassociates* his tables from the Swiss tables) You can't say that the algorithm testing counts, and the in use DCI from the same algorithm doesn't!!!! Perhaps he has not ever heard of anyone being hit using an Aladin pro! I've seen lots of air divers hit on a pro in just the last 12 months! Two were using O2 at 6+3m as a hedge!! I don't belive that any keen deco diver will have not seen DCI on pro followers given a couple of years of diving. Last year I saw two divers hit on a repet dive. They used NTX 32 for a 20 minute dive to 40 m then 2 hours later used air for a multi level shore dive to 18 m. They followed their pros and stayed in within NDL's for the second dive. Another diver did 25 minutes at 46 m and decoed by the pro, air all the way, he ended up in the chamber. Another mate of mine did 20 minutes at 65 m and followed the pro. No chamber, but quite badly hit. Another mate of mine did 18 minutes at 50 m. Deco by the pro but stayed at 6m till the pro cleared, then did 10 minutes at 3m. Severe joint pain relived by O2. I saw a diver hit while diving air and O2 at 50 m for 20 minutes. He planned the deco with DRX on 130 but stayed on the line, on O2, till his pro cleared because he didn't like the beeping! He had headache, fatigue, blurred vision, confusion and lack of co-ordination. Cleared with O2. I could go on but I'm sure you get the idea!! I've been hit on a mix dive. I wasn't using MiG plan, I was using DRX set to 130 safety (roughly equal to adding 30% to the bottom time). I ran the dive through MiG plan on 16 compartments and full safety (20%) as a multi level dive, and I found that the MiG ceiling was *well* over my head throughout the dive. I also added 10 minutes of surface O2 which wasn't called for in either programme. I've seen several other divers hit in similar circumstances. Do you see why I feel that statements along the lines that this table is fully tested (by someone else) and we have never heard of DCI using it. Anyone can write a table and if they never bother to find out if it is safe then they can claim "I've never heard of a problem with it!" I've written a table myself, and I've never heard of a problem with it, but I'm the only one who has dived it!! But perhaps you need someone who was actually diving *MiGplan* rather than simply diving a profile allowed by MiGplan. OK, This happened three weeks ago; The diver conducted a normal dive on Heliair to 76 msw. The dive profile was governed by MiGplan set to full conservative (20%). On surfacing the diver complained of pain in the shoulder joints. He was placed on 100% O2 and DES was contacted (Divers Emergency Service). They contacted the local hospital and a discussion took place, the details of which I don't know. The diver was then transported to a MILITARY chamber who were set up to treat heliox DCI. He was initially taken to 60 fsw on 100% O2, then 100 fsw on 50% He 50% O2. He improved slightly. He was then switched to 20% He 80% O2 (PPO2 3.2 bar) and he improved greatly. After being held at that depth for some time he was raised to 60 fsw and then given a table 6 with full extensions. All 'air' breaks were taken on Heliox. He was still suffering some symptoms at the end of the table 6 treatment. Apparently a Heliox saturation treatment was considered but was rejected. Follow up HBO treatments where given to try to clear up residual symptoms. Ohh one other thing, while discussing air/air diving, Jody mentioned; "In practice, I don't like to decompress that long, so instead I come up at 1500PSI or 30MINS of deco." I hope you realise that your software is being used for *much* bigger dives that that every weekend. 120 minutes of NTX and O2 enhanced deco is not that uncommon over here. 60 minutes of air/O2 deco after an air dive is a dead stock, standard, normal dive. We do it every weekend. If you dove like that here people would look at you funny. Sorry this post has been so long, Cheers Jason O-)
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