You should not rely on others to get you out of trouble in regards to your u.s. kit.Some of you have already undertaken and passed the equipment speciality course, for those who wish to know more there is an equipment speciality course being run on Sunday 12th Sept, for the princely sum of £65pp inc certification, at the dive centre. I can hear you all saying yeah yeah yeah sell sell sell, but just be aware when your low pressure inflator, or HP swivel pin, mask/fin pegs, neo/tri seams, or regs start hissing don’t say you were not warned.Items of diving Equipment
Spares
Note from the editor - you can read about the 2002 Scapa trip here |
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Egypt - Sharm el Sheik Club Trip Well the annual pilgrimage to the delightful sunny climes of the Red Sea are nearly upon us again and to make life as simple as possible I have put the following notes together. Most of us have already travelled to Sharm before and are therefore familiar with travel arrangements, apart from timings. For the rest I would like to cover various points making life a little easier. The first point is about Visas. Visas will cost around £12 for the duration of our stay in Egypt. You can either send your passport to the Egyptian consulate by registered post and a cheque or postal order for £12, or obtain it at Sharm el Sheik airport before checking through. Payment of $20 is preferable as sterling coins are not acceptable, and it would then cost you £20. (Information gladly donated by Peter Morton Bless him). Passports will need to have a minimum of 6 months left before it expires. No inoculations are needed for coastal resort locations in Egypt. Currency is the Egyptian Pound (LE), and a rough exchange rate is 11 LE to £1. They will accept Dollars with glee. It may be a good idea to take Imodium for any upset stomachs. To minimise this happening try to avoid local water, including foods that may have been washed, i.e. salads. Insurance is not included in the trip price, but a tried and tested company is Divemaster Insurance, which will cover all eventualities of any dive trip. Forms can be obtained from either Divemaster or the Dive Centre. Luggage allowance to Egypt is 20kg. Hand luggage is what it say' s, and not suitcases the size of a house weighing 20kg. It is advisable, for those with soft dive bags, to pack regulator and computers into hand luggage to reduce chance of damage. Diving consists of 5 days boat diving, with the option, (at a further cost direct to Emperor Divers in Sharm), of night diving or a safari to the 2 World War Thistlegorm wreck . Weights and cylinders are supplied by the dive centre in Egypt, and included in the holiday cost. Taking your own webbing weight belt. On the dive days we meet outside the dive centre next to the Hotel, and taken to the dive boat by mini bus, (we are all on the same boat), and visit various dive locations. We arrive back more times than not at around 5 o'clock. Once back at the dive centre, we offload our dive kit into their secure stores, allowing time for a G&T or two, or more likely a bottle of that fabulous Egyptian beer. Entertainment in the evenings is this year being organised by James Bunnett, who happens to know some very interesting tank museums in the locality. We are staying in the 5 star Hotel Naama Bay. Rooms are all twin rooms with good size beds in case you strike lucky Graham. A minutes walk away is the throbbing, heart pumping, Mecca of Egypt, the Pirates Bar and many other more savoury hot spots. Flight details are as follows: Departing from South terminal Gatwick on the 24th October to Sharm el Sheikh with Monarch Airlines, flight number MON5264, leaving at 10.15, and arriving at 16.30 local time. Returning from Sham el Sheikh on the 31st October with Monarch Airlines, flight number MON5265, leaving at 18.45, and arriving back at South terminal Gatwick at 22.05. If there are any further points I have not covered, then please do give us a call at the Dive Centre. 01223 240818 Up-coming CoursesRescue Diver Course
A demanding and serious, but fun and rewarding program, the Rescue Diver course is designed to expand a divers knowledge and experience beyond that of a recreational level. This enjoyable course teaches you to focus on other divers, as well as yourself, and shows you how to recognise and prevent a diving accident before it occurs, and how to respond if one does. Although the subject matter is serious, the course is both intensely rewarding and enjoyable.
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Cornwall Club Trip - by Richard Allway Over the years of the Club running trips to various destinations around the world we find some are good and sometimes, for whatever reason some are not so good. This trip however was one of the good trips, even though we were a bit unlucky with the weather.
We all started arriving in Plymouth on the evening of Thursday 26th August and as arranged all went to a local watering hole to check the details for the following day. It was decided that as some people hadn’t arrived by the time our stomachs were starting to moan about the lack of food we should eat here as well. After the main courses came out the last four arrived, unfortunately for them they were no longer serving food, and that’s when you notice how friendly this club of ours can be. Someone jumped up and ordered some extra plates and everyone donated something to the hungry late arrivals, which instantly makes those that don’t know everyone, feel like part of the group. Friday we all got up in time to have breakfast, which with families all in attendance was a bit like a chimps tea party some of the time (Mush & Dallas really need to learn some table manners) and then it was off to the Dive Centre to see what they had planned as the wind was definitely blowing. Unfortunately the wind was too strong to go out of the harbour in the morning, so we decided to wait and see if the winds would drop back a bit for the afternoon. This left us with 3 hours to kill on a day when the weather was definitely against us, but undeterred we had a cup of tea and a chat it was decided it would be a perfect day for flying Mike’s kite. We were right, the wind was blowing a gale and this was a serious kite and after an hour, everyone had managed to hang onto and even control the said item, everyone that is except our resident Gorilla, Dallas, who at best could be described as the worst kite flyer on the planet. Then after a traditional meal of Cornish Pastie and tea we drove back to the Dive Centre for a weather update. As expected there was no change and we decided to go out on the boat and dive the Harbour, now the viz wasn’t great (2m) and we weren’t on the deepest dive I’ve done, but everyone came out of the water with a smile on their face, happy to have stayed with their buddy and manage to see Crabs, Congers and some strange metal objects. That night we all met up again for refreshments in our local and then off to bed to prepare for the early morning start and better weather. Saturday morning we arrived back at the Dive Centre in the wee early hours, well 07:30, and we thankful to see the wind had totally deserted and a beautiful summers day was on the cards. By 08:40 we were kitting up over the wreck of the Scylla on the RIB and preparing for our first dive of the day, I won’t remind Simon that by this time of day you really should have checked that your weight belt was on the boat, but at least the rest of us enjoyed a good dive. The Scylla sits in 24m with her decks at 9m making it a very easy dive to do and one of the most enjoyable, mainly due to the fact that it’s a very interesting and with the correct training, a very easy wreck to penetrate. We spent a good part of the dive exploring the inside before making our way back to the shot line to get back on the RIB. As we’d split into two groups for the diving, it was soon the turn of group 2 to get on our boat and make their own way to the wreck whilst we had a late breakfast and as everyone will agree the day went according to plan with most people getting a couple of dives on some great wrecks. That evening we all met up a an Italian Restaurant that we had booked and with 4 children 11 divers and 5 wives or girlfriends making the trip it was a large table. Thankfully the food was great and the wine flowed freely for the entire evening. We would also like to thank Claire for demonstrating why she should be picked for the next Olympics, when she made one of the fastest recorded dashes for the loo’s with an upset stomach. Don’t worry Claire we did apologies to the waiter that you knocked flying on your way out the door. Sunday unfortunately returned to a very windy day, which meant only one dive was possible, however it did leave us a bit of time in the afternoon to relax before some set off home. The rest of us enjoyed a final night out in Plymouth and a very enjoyable trip around the British Navy ships on Monday (it was also the weekend when the Navy shows off it’s hardware for Navy Day) before tucking into Fish & Chips and setting off home. Now that’s what I call a good weekend.
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| How safe is a safe ascent - by Paul Hart As we will all remember from our Open Water course,18 metres a minute is the fastest we should ascent from a dive, however recent publications in the diving press would indicate that there is now evidence that a maximum ascent rate of 9 metres and minute and a safety stop at half the depth of your dive followed by another at 5 metres is a better approach. Now we all know that diving is a pretty safe sport but there are still over 1000 cases of DCS reported a year. 65% of these are type II, or neurological, and apparently related to the spinal cord which has a tissue compartment half time of 12.5 minutes. This means it takes 12.5 minutes to lose half of it’s nitrogen and a further 12.5 minutes to lose another half of what’s left. I also means it takes on nitrogen at the same rate i.e it is half saturated after 12.5 minutes, three quarter saturated after a further 12.5 minutes and so on. Mathematically speaking it takes 6 tissue half times for a compartment to be completely saturated or desaturated. The table below shows this.
Therefore if we were to make a 30 metre dive for 15 to 20 minutes the tissues that would accumulate most of the inert gas (nitrogen) would be the fast saturating blood and neurological tissues (5 10 and 20 minute possibly) of the spinal cord and brain. OK so lets assume we now apply this to a dive to 30 metres for 20 minutes – the maximum on the RDP. The spinal cord will now be heavily saturated with nitrogen. An ascent rate of 18 metres a minute would get a diver to the surface in 1.6 minutes and even with a mandatory 3 minutes at 5 metres they could be on the surface in around 4.5 minutes – still not much time to off gas the 12.5 minute compartment. If we slow to 9 metres a minute with a 3 minute stop at 5 metres this increases to 6.3 minutes which is better. But what if we now add another safety stop at half of the maximum depth of the dive – 15 metres for 5 minutes and extend the 5 metre stop to 5 minutes. The ascent now takes 13.6 minutes which is more than the half time of the 12.5 minute compartment, allowing this compartment to desaturate to less than half it’s maximum allowable. Even if the diver ascends much faster than 9 metres a minute, or even 18 metres a minute, between the stops they will still take more than 11 minutes for the ascent. This is the typical Haldanian approach. John Scott Haldane theorised as long ago as 1904 that a diver could quickly ascend to a depth which was half the absolute pressure of their maximum depth and not experience DCS. After time to off gas the diver would then ascend to half their depth again using the 2:1 ratio and off gas again, thus went the off gassing cycle. This theory was proved effective in tests with goats and was found to be much more effective than a slow linear ascent – the other theory of the time - which led to the demise of several of the goats during the tests. Following the successes of Haldane’s tests The Royal Navy used Haldanes theory for more than 50 years as did the US Navy in formulating the dive tables. Now what do we do today – a 30 metre dive with a slow linear ascent to 5 metres virtually the same profile as those that proved to be less effective in 1904. So what happened to the Haldane theory ? – why did we appear to drop the deep stops which had proved so effective. Much of this occurred when the US Navy developed it’s tables. They felt that much higher ratios, as much as 4:1 instead of Haldane’s 2:1 could be used with the fast tissue compartments. Meaning that they could ascend to the surface directly from 30 metres without a stop. In 1958 the ascent rates for US Navy divers came under review. Cdr Fane of the West Coast Underwater Demolition Team wanted ascent rates of 30 metres/minute for his men but this was thought to be too fast for hard hat divers used to a 9 metres/minute ascent rate, so a compromise of 18 metres/minute (60 foot/minute) was made, this also equated to a convenient 1 foot a second. The Navy used this rate as did many tables and dive computers up until 1993 but more recently dive computers now use a slower 9 metres/minute. With the highly selected Navy divers these faster ascents and no stops did not pose many problems. However now that recreational divers are pushing these limits it appears that although they have not exceeded the limits of their computers some are still showing signs of DCS. These profiles cause the supersaturation of the faster tissue compartments like the blood, and more importantly the spinal cord and brain and with faster ascents there isn’t enough time to allow these compartments to off gas sufficiently without generating bubbles. Recreational diving which includes more repetitive diving than the Navy does, challenges the faster compartments and the types of injuries divers sustain gives this support. Technical divers are now using decompression models such as the Wienke Reduced Gradient Bubble Model (RGBM) and the Yount Variable Permiability Model (VPM) which both attempt to predict when bubbles form and calculate stops to prevent bubble formation before surfacing. These profiles tend to add deep stops to the dive profiles used by technical divers and have proved very effective in reducing DCS injuries in deeper technical dives. The secret of deep stops rests in the paradigm of 'Beating the Bubble' rather than 'Treating the Bubble' . The former uses the deep stop to ensure that fast tissue supersaturation is not exceeded and stops bubble formation. The long ascent to the 5 metre stop, as is currently done, involves 'Treating the Bubble'; scientists know that this can produce 'silent bubbles' on the surface - bubbles that are so small they do not produce signs of DCS - but they are indicators of potential DCS. Most of us now dive with computers and follow them during a dive, during our ascent we rely on them to give us a safe ascent speed, but next time you are coming up from the hydro box at Stoney think about a short swim along the cliff face for 5 minutes rather than going straight up the line. A hundred years ago one man said this is the best way to do it - modern diving science is now proving he was right. Paul Hart Extracts from DAN Europe News on DCS prevention |
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As you all know the newsletter is not as frequent as it used to be. We would love to produce something on a more regular basis but for that to happen we need something to write about. So if you have a diving story about a recent trip or just want to ramble on about some diving related subject (Fireman Sam gets away with it) let us hear about it and we'll try and get it into a newsletter. Just email it to me at this address support@cambridgediveandwatersports.com.
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