Normally the ferries coming to the Isle of Man run at sensible times, but there is one particular scheduled service that leaves the port of Heysham at 02.15. In the winter, when the only other crossing is 14.15, I seem to find myself on the ‘overnight’ boat far more often than I would like. The boat doesn’t load until at least 01.30, so for a couple of hours I usually try to sleep in the carpark. Cold, rainy and situated next to the nuclear power station, it’s not exactly conducive to any restful sleep. Even if I do doze off I still have that dreadful anticipation of being woken by the port staff to drive onto the car deck.
I’ve learned now to book one of the cabins on the ferry. Head to the customer services desk, collect the key and find the cabin with the beds made up ready. If I’m quick I can kick my shoes off and be asleep before the safety announcement. The journey is just under 4 hours and the arrival in the Isle of Man is accompanied by an announcement and the lights in the cabin coming on. It doesn’t feel like I’ve actually slept at all. After a short drive home, I usually try for more sleep, but it’s not always easy during the day. I usually need a good night’s sleep to recover from my acute sleep deprivation.
As divers we often travel some distance by road, ferry or plane to get to our dive destinations. Travel arrangements can involve early check-ins and sleeping in unfamiliar places. There is considerable research into the effect of sleep deprivation and its effect on behaviour, particularly for in relation to driving. Sleep deprivation has the same hazardous effect as being drunk. Research has shown that being awake for 17-19 hours impairs performance to an extent that is comparable to having a blood alcohol level over the drink driving limit for the UK. As drink-driving has now become socially unacceptable, how many of us are aware that our driving could be as impaired by lack of sleep?
I think back to my days living in London, getting up at 4am to tow the club boat to the South coast, two waves of two dives and some food followed by the drive home. The boat would be stowed away by about 10pm, so the last few hours of towing a rib would have had me well into the fatigue zone. The evidence suggests that performance decline sets in after 16 hours awake, add this to sub-clinical decompression related post-dive tiredness and I think I was in dangerous territory.
How many times though do our trip risk assessments include fatigue? I got up at 5am this morning to collect a group coming in from the ferry. During the summer there is an 03.00 crossing from Liverpool arriving in the Isle of Man at 05.45. If I think I felt tired as I arrived at the ferry terminal – you should have seen the divers we collected! Some of them had managed a little sleep in the airline style seats, but not much. We’ve brought them back to the accommodation and sent them all to bed. We expect to be diving this afternoon, and one of the risks I’m now assessing is how much sleep they haven’t had.
I can’t find any specific research into the impact of fatigue on diving, but I am happy to accept that driving is a reasonably good surrogate activity. Drowsy drivers experience difficulty remembering the last bit of road and slower reaction times. Impaired cognitive and motor performance aren’t good for divers either. We learn about the impairment due to narcosis (with that amazing slide that has several pints of beer on!), but being awake for long periods is going to cause those effects without even stepping in the water. Maybe there are hints about this in our training, we do advise to have a good interval between flying and diving, but there’s nothing explicit regarding sleep deprivation. If you aren’t convinced that this is a problem, perhaps you should know that it’s been estimated that sleep deprivation is implicated in 1 in 5 road accidents. Sleep deprived drivers are much more likely to get angry with other road users and deal poorly with stressful situations (like navigating unfamiliar roads).
Caffeine can help, but only in the short term and not with all the aspects. It can improve alertness and reduce reaction time, but fine motor control isn’t improved even with high doses. So, I could send all the divers to the local coffee shop and insist they top up their espresso quota, but I know that won’t last. Instead, I hope they have their heads down and are napping now. Me? I’m too wide awake and writing columns instead!
Seals are collectively known as pinnipeds, which means from the Latin pinna (fin) and pes (foot). This classification includes the walruses, eared seals and true seals. The Isle of Man and the rest of the British Isles are home to resident populations of Grey seals (Halichoerus grypus) and Common seals (Phoca vitulina). Common seals (also known as Harbour Seals) are found in both the North Atlantic and North Pacific. About 35% of the European population of common seals lives in UK waters. By contrast Grey seals are only found in the North Atlantic, Baltic and Barents Sea. The entire world population of Grey seals is probably no more than 400,000 individuals, with about 40% of them living in UK waters. Although we tend to take seals for granted, we should perhaps appreciate how lucky we are to have them in the waters around us and see them so often.
There’s been a long understanding that the pinnipeds evolved from land based mammals. This concept in itself is a little strange, as the general gist of evolution is that our ancient ancestors left the watery environment for a life on land. But somewhere millions of years ago, some of the mammals returned to the sea to take advantage of the feeding opportunities that existed there. Whales and dolphins have definitely taken their return to the marine environment to the extreme and evolved to the point that they can no longer safely return to the land. When they do, the amazing guys from the British Divers Marine Life Rescue swoop in and work their hardest to throw them back into the briny again. In the pinnipeds we have a group of species who spend their time mostly in the marine environment, returning to land only when necessary. On land seals are ungainly, slow and clumsy, which made them an easy target for hunting. In the water, they are agile hunters, capable of diving to about 200 metres for up to 15 minutes.
The clues to the pinnipeds evolutionary past are clear in a number of ways. Their forelimb has five webbed fingers, with claws that are used for grooming and fighting. This five fingered (pentadactyl) limb structure is a common evolutionary feature, linking many vertebrates including reptiles, birds, mammals and amphibians. Just let that sink in for a moment. You can see the same bone structure in pretty much every group of animals with bones. The humerus at the top, an elbow where the radius and ulna join, a wrist connecting to fingers. It’s there in the bats wing (with elongated fine boned fingers and skin stretched over them), it’s there in frogs (although the ulna and radius have partly fused), and cats and dogs and tigers and crocodiles and in us..
In seals the flipper bones that would be the equivalent of your arm are shortened, so that what appears to be their armpit is in fact their elbow (front flipper) or ankle (hind flipper). Their metatarsals (fingers) are elongated compared to ours and the skin in between gives them something akin to swimming gloves. Close interaction with a seal will reveal that they can still bend their webbed fingers to grip and hold onto objects or, if you are lucky enough, onto you as you are diving. Their flippers are well adapted to propel them through the water. When swimming quickly, the hind flippers are used in a side to side motion, and the front flippers are held against the body. If you have watched seals turn under water, you’ll know that they stick out a front flipper to perform sudden changes of direction. Cruising speed for seals is about 2 to 3 knots, but when hunting seals can move at an astounding 20 knots (that’s probably faster than most club ribs!).
Seals are part of the Caniformia (dog like) sub order of the Carnivora group of Mammals. In fact, most divers that have had encounters with seals will tend to describe them as being like big puppies. Despite this, there have been many studies suggesting that seals are in fact more closely related to bears than they are to dogs. Perhaps the fact that we are more likely to have encountered and interacted with dogs rather than bears gives rise to our misconception? Remember that Grey seals are the largest living carnivore in Britain, can grow up to 2.3 metres and weigh over 300kg and treat these amazing creatures with the respect they deserve. When you get to shake hands with a seal next time, count his fingers and say hello to a very distant cousin.
They're all divers to me....
One of the best things about running a dive centre is the diversity of the clients that walk through the door. One of the worst things about running a dive centre is the diversity of the clients that walk through the door. Our centre is multi-agency which means we can honestly offer the most suitable training to each person that comes to us. We’ve become experts at chatting to prospective divers about their interests, travel plans and diving aspirations and offering them considered and justified advice about their training.
But when people walk through the door the first thing they will say is “I want to do my PADI.” The marketing spend and brand awareness for PADI is huge and there’s the common misconception that only a PADI cert will be accepted elsewhere in the world.
Like many experienced divers, I’m entitled to carry a range of cards covering a number of different aspects of diving, but I pick which ones I take on trips with me. Somewhere in one of my filing cabinets is my set of cards but rarely do they see the light of day. I once had the misfortune to be on a Red Sea liveaboard with a guy who when asked to prove his diver grade slapped a huge wallet of cards on the table with the classic line “There’s 50 years of diving experience in there. Take your pick.” It was unnecessarily aggressive and made all the sweeter when, later in the trip, this same guy was the one who surfaced from the night dive to check where the boat was before dropping back to 12m to finish his dive. Obviously the 50 years of experience didn’t include basic navigation.
In truth, BSAC qualifications generally carry a large amount of kudos. We train in some really tidal, very murky conditions and our training includes a huge amount of dive and rescue planning that stands us in good stead wherever we pitch up in the world. On a particularly difficult pick up from the Rosalie Muller in the Red Sea it was our experienced divers who took over recovering the divers from the water, threw out grab lines and carefully timed their assistance with the pitching of the boat. No shouting. No fuss. They just stepped forward and stopped a difficult situation developing into one that would have ended up in the BSAC incident report.
The Isle of Man hosts motorsport events throughout the year, the TT in June, Southern 100 in July and the Manx Grand Prix in August. These events attract large numbers of foreign visitors carrying a variety of dive qualifications, some stating CMAS equivalence and several requiring translation. We’ve met and dived with some fantastic divers from around the globe, and we’ve had some very deluded people walk through the door. My favourite has to be the bloke who walked in and announced in a very heavy Eastern European accent “I vant to dive vith the sharks!” A little gentle questioning established that he had done a try dive, in a hotel swimming pool in Turkey, about 5 years ago. We carefully explained how much legal protection covers the basking sharks that come to pup and breed in Manx waters, that they avoid divers, that he wasn’t qualified and no, we couldn’t just hire him some kit. He left muttering and we breathed a collective sigh of relief.
We run two boats from our dive centre and when necessary have the services of a third boat. The skipper’s first question when I call him to book a group is to ask “Are they BSAC? That’s OK then.” He knows he will get divers who, thanks to the strong club system, will turn up as an organised team and just get on with it. Delayed SMBs aren’t a special course, they’re mainstream. Nitrox isn’t something just for multiple dives on a liveaboard, but for safety in everyday diving. And should anyone have any difficulty there will be someone throwing out a grab line and watching the pitch of the boat as they go to assist.
But of course I’m not claiming BSAC clubs are perfect. We’ve had the divers who got confused when they ran out of dishwasher tablets and put washing up liquid in the machine instead (Don’t try this at home without a mop and bucket handy). We’ve had the clubs that plead for discounts, usually for the ‘poor students’ and their trip turns out to be comprised of university staff and post-docs on sizeable bursaries. And we all look forward to hearing about the club politics as the week goes on.
Michelle has been scuba diving for nearly 30 years. Drawing on her science background she tackles some bits of marine science. and sometimes has a sideways glance at the people and events that she encounters in the diving world.