​Scallops (Pecten maximus) are a national concern on the Isle of Man. We have some of the most protected scallop populations in the British Isles. Licensed boats can only fish during daylight hours in certain areas of the sea and not during the summer months when the scallops are breeding. The catch is landed into harbours around the island; creamy, pink shells in 25kg bags loaded onto pallets for the forklift truck to move them into wagons.
If you glance down into the harbour its usually possible to spot the white inside of a few discarded shells shining on the seabed below. These shells eventually wash across the bay and onto the beaches, but they don’t always arrive in the same colour as when they were discarded. Many of the shells are stained dark brown or black, colours we never see during dive surveys of scallops.
Shells are mostly made of calcium carbonate which is white in colour, mixed in with about 2% of protein. As molluscs develop they absorb minerals from their environment and secrete calcium carbonate from their mantle to create their shell. The protein makes the shell very strong, but lightweight and resistant to dissolving in water. Shells are self-repairing, and the mollusc can secrete more shell material as needed for repair or growth. Naturally occurring colour and patterns in shells is as a result of mineral ions incorporated into the shell structure. But that doesn’t explain the post-mortem colouration of the scallop shells.
Shallow burial of shells causes iron oxides to form in the tiny pits on the surface of the shell and causes brown staining. The black colour is usually due to microscopic crystals of iron sulphide. These crystals form in the absence of free oxygen which can occur if shells become buried deeper in mud or sand.
Although my local harbour is sheltered, it doesn’t provide the deep mud conditions required to blacken shells, but there is a much more common cause. Burial under just a few centimetres of seaweed rotting on the beach will provide suitable anoxic conditions for sulphide formation. Hence blackened shells on the beach is a relatively quick process occurring under mounds of kelp and wrack.
There are some mollusc species that live well buried into deeper sediment. The Ocean Quahog (Arctica islandica) is a subtidal species of clam that is renowned for it’s longevity. Some individuals have been recorded at over 500 years old. The shells of Quahogs have dark black colouration, but they have a long time to absorb the necessary pigment. Whilst the shell is buried in the sediment, a siphon to the water provides for food and oxygen to the creature below.
Naturally acquired pigment probably strengthens the shell. Colour patterns often align with spiral or axial sculpture. Instead of producing and transporting a thicker shell, it might be more energy efficient for molluscs to make pigments. Pigments impede propagation of a crack in the shell. The structural explanation also works for colour inside of shells. A good example is Mercenaria mercenaria (the quahog or cherrystone clam). The purple inside the shell, hidden when the animal is alive, lies along the edges of the shell, just where predator whelks are likely to attack. Strangely young Merceneria don’t make the purple pigment. Their shells are too thin to resist attack anyway, so they concentrate their efforts on growing a thicker shell and surviving to when their pigment strengthened shell is going to ensure a long life.
There are lots of other reasons for shells to have different colours.  A favourite project for marine science students is to send them to look for colour variation in Flat Periwinkles (Littorina obtusata). In this case pigment is used for camouflage, allowing the winkles to hide amongst the bladder wrack on the shore. Pigments may serve as a warning to possible predators, or the pigmentation pattern may provide a template for future growth of the shell. But there doesn’t have to be a reason for pigmentation in all cases. Oxygenated mammalian blood is red, not for any evolutionary reason, but because that’s the chemistry of the situation.

​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.

​Sellafield is located across the Irish Sea on the Cumbrian coast and is approximately 32 miles from the Isle of Man, on a clear day you can just about see it. The main activities at the plant include reprocessing of spent fuel from nuclear power reactors and storage of nuclear waste. There are no longer any nuclear power plants in operation at the Sellafield site. It was built in the late 1940s to manufacture plutonium for atomic bombs and Sellafield is one of the most radioactive places on earth. In its prime the plant was releasing eight million litres of contaminated waste into the sea every day. In 1957 the plant became the site of the worst nuclear accident in Great Britain's history, The Windscale Fire. This was a blaze that raged for three days, releasing radioactive gases into the air. The discharge of low level liquid wastes from the Sellafield site in the north west of England is the most significant source of artificial radioactivity in the Irish marine environment.
Now the site is mainly used for nuclear fuel reprocessing, and this and other activities gives rise to the discharge of low level radioactive materials in the form of liquids and gases into the environment. These discharges are regulated by the UK authorities and limits for releases are set by the Environment Agency of England and Wales (EA). Liquid radioactive waste is discharged from the plant into the Irish Sea via a pipeline, about 3 km from land. Gases are released from the plant via a number of chimneys (referred to as ‘stacks’). Discharges into the Irish Sea peaked in the mid-1970s and have dropped significantly in recent years. This is as a result of improved waste treatment facilities at Sellafield, which convert much of this radioactive waste into a solid for long-term storage.
As a result of the discharges from Sellafield, low levels of artificial radioactivity can be detected in sediments, seawater, seaweeds, fish and shellfish taken from the Irish Sea. A wide range of marine samples are collected and analysed on a regular basis by both the EA and the Manx Government. This monitoring can show where the radioactive particles become concentrated.  As expected many particles end up in sea bed sediment, so there are sometimes slight increases when the winter storms have been especially ferocious and stirred up the seabed. Generally, levels are falling from their peak in 1998. 
There are several radioactive isotopes that are monitored, Technetium-99, Caesium-137 and 134 and Cobalt-60. Of these, Tc-99 is regularly tested for by catching lobsters. Tc-99 concentrations in our local lobsters have declined from a peak of around 400Bqkg-1 in February 1998 to average 10 Bqkg-1 during 2015. These Tc-99 concentrations are lower than the levels found in lobsters caught off the Cumbrian coast. The EC recommended maximum permitted level for Tc-99 in seafood which is 1250 Bqkg-1, so these lobsters are safe to eat and regularly eating seafish will only make a minor contribution to your overall radiation exposure.
Now it’s not true to say that lobsters are immortal, but once they reach adulthood they don’t have many predators except humans. Good lobster fishery management sets minimum landing sizes for lobsters, ensuring that they are at least able to breed once before being caught. Small lobsters can get out of pots through the escape hatch or they are returned to the sea anyway.
Just as lobster pots discriminate against small lobsters, they also prevent very large lobsters from getting in.  Consequently, larger lobsters do tend to live a very long time.  The lifespan of European lobsters has been estimated at between 30 and 50 years.  Large lobsters have lived through the peak discharges from Sellafield, unlike their smaller 3-4 year old counterparts who got caught in lobster pots and tested. Lobsters have a fairly high affinity for Tc99 and they accumulate the radioactive particles in their bodies. But the only real predator for the large lobsters is, you’ve guessed it, divers. 
Something to think about the next time you wrestle a monster lobbie from under a rock

​Somewhere back in your very first diving course there will have been reference to air being compressible because it’s a gas, as opposed to water being non-compressible. When we start thinking about how molecules interact, it’s helpful to go back to school science. In solids the molecules are packed tightly together, they can vibrate but they aren’t free to move around much. In liquids the molecules can move but stay interacting with each other and in gases the molecules fly around freely bouncing off the walls of whatever contains them.
Thinking about gas molecules as random whizzing around bumping into other molecules and their container, it’s easy to understand why if we push more molecules into the container the number of collisions with the container wall will increase and the pressure goes up. This kinetic model of gases assumes that the gas particles themselves are very small (they are) and there’s a lot of space between these gas particles. That leaves lots of extra space for us to jam more molecules in there and compress the gas together. Hence gases are compressible.  This nicely explains Boyle’s Law (remember that?) but makes a number of assumptions which create a concept of an ‘Ideal gas’. Sadly, Ideal gases don’t exist and we have to deal with real gases. But at low pressures Boyle’s Law is fairly useful.
Liquids don’t behave in the same way because the molecules are already close together and interacting to a limited extent. Each molecule forms temporary associations with the other liquid molecules. If you heat up a solid to melt it into a liquid, you can measure the temperature increasing. As you get to the point where the solid it melts, the temperature will stabilise (even though you are still heating it). This is the point where the molecules are absorbing heat energy to give them the kinetic (movement) energy to move around. Once all the solid molecules have absorbed enough energy to melt into liquid, then you can see the temperature start to rise again as you carry on heating it. During this phase the molecules will move faster, but they still interact with each other. Keep heating and give them enough energy and they will manage to escape the interactions and form a gas.
Water is a bit of a strange liquid, because it’s molecules interact more than other liquids, and this gives it some strange properties. Water molecules form hydrogen bonds to other water molecules, and then they break these bonds and reform them with other nearby water molecules. Although these bonds are quite weak, there are lots of them. If it weren’t for hydrogen bonds then water wouldn’t be a liquid at all. When the other elements in the same family of the periodic table, like Sulfur and Tellurium, bind to hydrogen they form gases not liquids.
Water is most dense (the molecules are packed tighter together) at 4 degrees. At this temperature the hydrogen bonds are quite structured and pull the molecules tighter. As the temperature rises the bonds start to make and break more frequently and allow the water molecules to move a little further away from each other, so water becomes less dense. At temperatures below 4 degrees, hydrogen bonds don’t form so well and so as water cools to become a solid, it also becomes less dense. This explains why ice floats on liquid water (good news if you’re a polar bear) and why cold water sinks into the ocean (that’s  thermoclines).
So, these little fairly weak hydrogen bonds have a lot of influence and it’s them we are fighting against when we try to compress water. They have already done the job of pulling the oxygen dihydride molecules far closer together than we’d expect from the other elements in their group. It’s because of them that water isn’t a gas at room temperature.  And once we’ve got as far as forming a liquid, there isn’t much compression left to achieve. At 4km down in the ocean, water has a measurable compressibility of just 1.8%. It’s not quite true to say water isn’t compressible, it’s just not very compressible and for the depths that we will visit we can probably ignore the marginally increased density.
Resistance to compression for any substance can be described by the bulk modulus value. This is a measure of how much pressure must be applied to reduce the volume by 1%. For solids, these values are predictably very high, eg diamond is 443,000,000,000 Pascals and steel is 160,000,000,000 Pa. For ice I would need 2,000,000,000 Pa to compress it by 1%.  For liquids we would expect the values are lower and generally they are. Water bucks the trend though and needs 2,200,000,000 Pa. So, I actually need more pressure to compress water than I do to compress ice. Blooming pesky things those hydrogen bonds!

​As divers we all know about the difference between diving in fresh and seawater in terms of needing an extra bit of lead because seawater is just a little bit denser than freshwater. Density is affected by 3 things, salinity, temperature and pressure. At extreme depths the density of seawater increases due to the high pressures. Given that we are recreational divers, the increase in density due to depth isn’t something we need to worry about. There are two common ways of dealing with measuring the density, we could use the density figures in grammes per cm3 or specific gravity.  Specific gravity is a comparative scale, but it’s actually fairly easy to calculate actual density using the temperature and salinity for where we are diving (and there’s some great online software that allows you to plug in the relevant figures).
Salinity (how much salt in g is dissolved in 1kg of water) varies quite a bit around the world. To understand the factors affecting salinity you would need to look at how much freshwater run off enters the area. Freshwater is less salty and will have the effect of partially diluting the salt concentration. Local climate will influence how much water evaporates from the sea; in hotter conditions the concentration of salt rises. Lastly, we need to consider how much current circulates the water. One of the most saline seas is the Red Sea, with little freshwater, high temperature and confined circulation. Salinity levels at the northern end can be as high as 4.0% (much higher than the world average of 3.5%). By contrast, in the Baltic Sea, especially around the Gulf of Finland and the Gulf of Bothnia, salinity can be as low as 0.8%. There’s lots of freshwater running in, limited circulation of saltier water through the narrow channel to the North Sea and the lower temperatures reduce evaporation.  This sea water is so not salty that it could be safely drunk in a survival situation. In the UK we actually see a little variation between the west coast (3.5%) and the east coast (3.4%). Don’t try drinking this stuff for survival!
So salt levels can vary, and as they do, so will the density of the water that you need to displace. How often have you heard someone in a dive resort tell you that you might need a bit more lead here because the seawater is a bit more salty? This got me thinking, how much more salty would it need to be for me to notice,or are there other explanations?
Let’s start with the UK. The density of seawater on the Atlantic side at average temperature (assume 12oC) is 1.0267 g cm-3 whereas on the North Sea side, the density will be 1.0258 g cm-3. I know from experience that I haven’t noticed the difference. I do know that wearing twin 7’s in fresh water (1.000 g cm-3) means I don’t need any additional lead, but exactly the same setup in Manx seawater takes 4kg of extra lead. So, for each extra 0.0067g cm-3 I need another 1kg of lead to get my head under water. Taking this logic forward means that in the salty Northern Red Sea at the coldest part of the year (24o), when the density is 1.0275 g cm-3 I’ll be needing another 1kg to sink, which seems reasonable. But, and it’s a really big but, I don’t wear the same neoprene drysuit, Fourth Element undersuit and base layers in the Red Sea as I do in the UK. If I did, I’d need the extra lead and treatment for heatstroke!
The Red Sea is a bit of a salinity extreme; for most of the world the average salinity applies, which makes it pretty much the same as the UK.  I think it is much more likely that other factors come into play when we head off to other waters. Every time I drag my 5mm wetsuit out I struggle to remember just how much weight I had last time, and of course my suit will be compressing with use and losing buoyancy from new anyway. I err on the side of caution and take an extra lump of lead for the checkout dive. Let’s face it we would all rather be under the water having to control a little extra air in our BCDs than bobbing around like a cork on the surface while the dive master forces a smile and swims over to us with another block.
Most of us will use cylinders from the dive centre and there can be a huge variation in the weight of steel cylinders. A 12l cylinder can weight between 13 and 15 kg, and a 15l can vary from 16 to 19kg. Unless your dive centre has cylinders of different weights, they may not even appreciate that they have ‘lighter’ 12s. The situation is worse still if the cylinders are aluminium and are neutral in the water…then you’re really going to need some lead round your waist! Your confusion at needing more lead is easily explained by blaming it on the ‘salty water’ but perhaps there are more factors at play?

​At the end of 2016, diver training agencies including BSAC launched Sea Survival training courses developed in conjunction with the RNLI. Despite the common view of the RNLI as being the provision of lifeboats and crew, there is much more that they are involved in from a safety at sea perspective, with particular foci on fishing industry accidents, Swim Safe training courses and safety advice for all water users. It’s astounding how many fishermen don’t wear lifejackets, especially local pot-boat skippers who often work alone.
To try to educate fishermen the RNLI brought a dozen of them from around the UK down to their training base in Poole. All the skippers had previously attended the mandatory Personal Survival Techniques course (and it’s predecessors) which are run in swimming pools around the country. The RNLI trainers asked about lifejackets and got the usual story, the fishermen had them but rarely wore them. The general feedback was that as strong swimmers they were confident that should they fall in the sea, they would be able to swim back to their boat, climb up the tyres on the side and self-rescue. Interestingly, qualified divers and anyone who swam in the sea was excluded from the test group. Repeated attendance at sea survival training had led each fisherman to conclude that their lifejackets weren’t necessary.  The RNLI sought to challenge that belief.
The night before the training course, the trainers opened the doors around the training pool to let out the heat. Overnight the water temperature dropped to 15 degrees.  If you are a diver around the British Isle I am sure there are days where you dream of 15 degree water! At the first attempt the fishermen were asked to wear their normal deck attire and jump in to deep water to simulate falling off their boat. With no life jackets on, the impact of cold water shock was immediate. None of the 12 fishermen lasted longer than 5 minutes before a rescuer intervened. Post dip interviews revealed their shock and surprise at how debilitating the cold water was, definitely nothing like their sea survival training course.
Cold water shock is an immediate short-lived response to immersion in water less than 15 degrees. Blood vessels at the skin contract rapidly, increasing blood pressure and the heart rate. An initial gasp for air can be followed by a breathing rate that is 6-10x higher than normal. It is likely that cold water shock accounts for most deaths when people have unexpectedly entered the water. If you are not wearing flotation during this phase, keeping your head above water becomes the biggest problem.  Over the next 10 minutes, cold incapacitation reduces blood supply to the muscles, making it difficult to swim or self-rescue. A crew member throwing a life ring to you during this time will be frustrated that you can’t actually hold onto it or kick towards the safety of the vessel.
The following day the exercise was repeated but this time with lifejackets being worn. The same cold water shock reaction was initiated, but the fishermen didn’t have to work so hard to keep their airway out of the water, the cold incapacitation stage took longer therefore improving their chances of getting back to the ladder on their boat. You can see the videos from this exercise on the RNLI website.
This started me thinking about why divers were excluded from the test group. I’ve realised I still brace myself for the cold water after decades of diving. OK, I’m wearing a drysuit and the cold water shock reaction is pretty much limited to my head and hands. But how many of us drop beneath the surface in anticipation of that brain freeze moment? As the blood vessels rapidly contract they stimulate the trigeminal nerve sending pain signals to your brain. It hurts for a few moments until you become acclimatised. The fishermen in the RNLI training exercise couldn’t get past that brain freeze feeling.
I think we sometimes underestimate the impact that cold water immersion has on new divers. I can recognise it enough now, but when I think back to learning in a wetsuit I can remember the feeling of panic, rising heart rate and accelerated breathing rate as I used to get into the water. Although we will all recognise increased air consumption by trainee divers, perhaps part of this is their reaction to cold water immersion? I’m sure that with experience comes the anticipation, the forced control of breathing rate for the first few seconds, but until our new divers have developed their response, maybe we should keep a close eye on them for those first couple of minutes? If your trainees are hoofing through their air and their buoyancy is being disrupted by their rapid breathing rate, maybe it’s something to consider?

​Some years ago I craved having a tropical fish tank. I’d had coldwater fish starting with the short-lived goldfish I won at the carnival hoopla stand, but tropical fish seemed like they were more interesting. The big problem is that a fish tank is a bugger of a thing to move and at that time in my life it became a chore and a burden. I relocated 6 times with the fish in bags inside a coolbox, hence it was with some relief that when the last fish died I emptied out the last of the water and put the tank away, promising that when life was a little less hectic I’d get it back out and set it up again. About 6 months later disaster struck when I cracked the glass at one end, but I didn’t get rid of the tank, just planned on repairing it. One of those tasks on my endless to-do list.
And then my goals changed. Stuff the guppies and their frilly tails, why not set up a coldwater marine tank? After all I spend a large amount of my life underwater, why not bring some of the great critters back? Several times a year I visit schools on the Isle of Man and bring a variety of sea creatures in to meet the children and explaining something about their lifecycles. I’ve developed a habit of going and collecting little stuff anyway.
A chance conversation with one of our club members who wanted to rehome one of his tanks, ended up in him loaning me a pump and a chiller unit as well as a fish tank without a crack in the end. At 10am we were having a brew in the dive centre and by 2pm I was stood ankle deep on the slipway filling a cleaned out sofnolime container with seawater. Our marine tank was installed and populated within 24 hours. And if I thought the tropical freshwater tank was hard work, I had another shock coming. Weekly 50 litre seawater changes are just hard work.
I now spend my time thinking about the ecological balance of the tank much more than I ever bothered with guppies. When you keep tropical fish there is loads of info about how many fish per litre of water etc, for British marine life tanks there isn’t the same guidance. A small edible crab was a disaster and massacred poor Kevin the Masked Crab within 24 hours. Kevin had a dodgy past himself, and was often seen amputating limbs from small brittle stars, so he was called Kevin the Killer Crab, but we had grown fond of him and it was sad to see parts of his exoskeleton scattered around the tank.
Our current population includes about 10 hermit crabs, who mainly seem to fight over shells and ignore the rest of the inhabitants. We have two small shore crabs, although one of them is getting a little larger and consequently even hungrier. I’ve a feeling he’ll be heading back to the shore next weekend. We’ve ended up with about 30 North Atlantic Prawns who pounce any food in the tank, and will come to your hand if you put it in. Small Purple Henry starfish, a juvenile scallop, a small common sea urchin, some limpets, Top Shells and Periwinkles complete the scene. We’ve had small fish (they get eaten).
The current star of the show is our Leach’s Spider Crab (Inachis phalangium). Leachy has a small triangular carapace which will reach a maximum of 3cm. I picked him as he ran across a sandy patch between rocks. I’ve seen small spider crabs before, but never really bothered too much about them.  Leachy’s small size made him a target for the tank. After a short trip in an old ice-cream container, he was released in the tank. On the same day, another diver brought in 3 small Snakelocks Anemones.
It turns out that Leach’s Crabs have a commensal relationship with Snakelocks Anemones, the crab benefits but not to the detriment of the anemone. Females stay with their anemone and males will rove around looking for a mate and then return home. They are beautifully camouflaged, with legs covered in sponges and algae. This isn’t by chance, Leach’s Spider Crab actively collects sponges and algae and attaches them to specially shaped spines on their legs and carapace. The sponges are unpalatable and stop predators from attacking the spider crab. The algae form a part of the diet, which also includes food debris from the anemone and the mucus from the tentacles. Our intrepid little Leachy has beautifully evolved to fit into his ecological niche. Admittedly, that’s not meant to be in a dive centre tank, but on the plus side, none of his natural predators are there. We’ve so far avoided large fish or octopus. Periwinkles occasionally find their way out past the pipe work so we’d have no chance of keeping a cephalopod and Leachy is safe for now and I’ve learned a lot more about him.

​Once upon a time my Editor and I went diving together.  It was a few weeks after he had penned an opinion that back entry dry suits were an integral part of the buddy relationship.  It was, he opined, important to trust your dive buddy to close the ridiculously expensive brass zip without trapping your undersuit or that annoying flappy bit of neoprene stuck in the back of several suits.  Relying on your buddy to ensure the zip was closed all the way, contributed to the mutual support aim of buddy diving.  As we stood kitting up for our dive, I happily fastened my front-entry plastic zip with the minimum of fuss and decided to tackle Simon about his ill thought-out piece. 
I have a front entry suit because I like being responsible for myself…or more precisely I don’t always trust my buddies, especially if my buddy is a trainee or new to dry suit diving.  I lack the ability to rotate my neck like a barn owl to check that everything is OK behind me.  It only takes one trainee, who earnestly assures you that the zip is closed when in fact it’s half an inch open, to make you reconsider.  When that cold rush of sea water starts running down your shoulder, you know that this is one mistake you won’t be making again! 
But how do you get the dive manager or boat crew to double check your zip without offending your buddy? Surreptitiously sidle over to the crew as you leave harbour, keep your voice low so it can barely be heard above the engines (and definitely not by your buddy) and assume some wistful position that doesn’t look like you’re hugging a large imaginary tree?  And of course all the while you must try not to offend your buddy and generate “trust issues” because at the very first time you are supposed to rely on their assistance you bailed and found another source of help.
So for me a front entry suit solves all of these problems.  If my zip isn’t closed properly, then that’s my fault and my soggy right leg. For anyone thinking of getting a suit with a plastic dry zip, they are fabulous but never ignore the need for silicon greasing the stop end, even between dives if you’ve peeled out of your suit. But it’s my responsibility and I’m good with that.
Front entry suits frequently have two zips, the dry one and a cover zip, and this can cause endless problems too.  I took my eye off the ball one day whilst doing a dry suit introduction in the pool.  I will accept some of the blame, but we had just done a session at the dive centre trying on suits, and the concept of a dry zip and a cover zip had been discussed as we established that this particular suit was a good fit.  I am to blame for thinking that our discussion would be remembered barely an hour later when we kitted up on poolside.  When I turned to look at my two eager divers, they had closed their zips and were ready for the stride entry. Yes, the cover zip was closed.  No, the dry zip wasn’t.  Yes, the suit filled with water (luckily the warm pool version). No, the diver couldn’t climb up the pool ladder unaided. The phrase “I seem to be getting a little wet” was a total understatement on her part.  Once dekitted, we laid the unfortunate lady down and rolled her around on the pool surround to empty the water.  To give her credit she laughed nearly as much as we did and gamely carried on the orientation session. Five years on she is still diving, in a front entry suit, which she knows has two zips and one of them is very important.
Sadly she’s not the only one who’s been caught out in this way.  Even some quite experienced visiting divers have missed the ‘hard to do up’ brass zip and relied on the ‘easy to do up’ cover zip in one of our rental suits.  A cold shot of Irish Sea water down the leg is a salutary lesson in the need to familiarise yourself with hired equipment.  So for anyone who read, noticed and remembered Simon’s treatise on the importance of back zipped suits for buddy trust and diving, maybe I was wrong to criticise him and perhaps divers with front entry zips could do with their buddy’s assistance, just sometimes. 

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.
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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.