Wednesday, May 28, 2014

Descent Checks - Vital on Every Dive

Periodic checks with your dive buddies while diving is always a good thing. Things can start to develop in a negative way, and fast. Just because you met your dive buddies on the hang line from the boat, or the edge of the cliff before descending into the abyss, does not mean something did not change. Things can happen at a moments notice. Descent checks are vital to the success and enjoyment of every dive.

Every now and then I'm on a road trip with my family where we are caravanning with other people. Prior to departure for the trip, we will plan out our schedule and where we are stopping, especially if we are separated. Fortunately, today's technology allows us to get up-to-date information with our phones by calls, text messages, or someone posting a status update on social media.

Scuba diving, on the other hand, does not have the luxury of technology while diving. Although some manufactures have created underwater housings for smartphones, most tech divers will not be bringing this along for a few obvious reasons. We do not have the luxury of saying "hey buddy, I need a little help" before you reach your final destination, such as a shipwreck at 150 feet. In a perfect world, maybe things will go just fine. The slightest problems can still happen between the surface and 100 feet while descending. I can list at least a dozen issues that have actually occurred on tech dives.

This is why descent checks are so important. To complete a descent check, you would perform the following tasks.

Check dive buddy for any bubbles from leaks in:

hoses and
tank valve or manifold (double tanks).
Make sure the hoses are properly routed, especially on a tech diving set up

Perform a simulated out of air and donate your long hose to make sure it is free from deco tanks and other hoses.
Ensure the canister light wire is free and clear for easy use when needed.
Ensure the deco tanks are in the right spot:
stacked in right order, or
tanks are on the correct side to prevent switching to wrong gas.
Check to make sure everyone is OK for the dive:

Someone may need to catch their breath from currents/task loading
A diver may be disorientated for a moment and need a few seconds to regain the missions focus.
There could be a chance a diver is having a bad day.
Aborting a dive at shallower depths increases the safety of the entire dive team.
Going deeper with this 'bad day' on your back will only accelerate problems when it is more difficult at depth to handle (cold, dark, enclosures, narcosis, etc).
The general rule I have used is to have at least two check points of any dive, regardless of depth. Typically, the first stop is done around 20 feet. The second spot will be a midpoint of the dive. For example, if you were going to 100 feet, you would stop at 20 feet and then 50 feet and then a final check once we reach 100 feet. You can modify this based on landmarks or turn points in the dive, such as a cliff or an actual turn. A check once you reach the bottom or destination adds a safety buffer. Especially when you are diving in cold, dark and arduous environments.

In a perfect world, these things should not happen to experienced tech divers, but they do. Why?

Murphy's Law

We are human

The descent check should also be done on recreational dives. If you are planning a 40 foot dive, you can do a check just below the surface around 10 feet and a check at the 40 foot mark. You may not do all the things a tech diver would do, such as a simulated out of air with a long hose. However, the principles are still the same by adding a safety margin to the dive.

The purpose of a descent check is to increase the safety of each dive, recreational or technical. By adding this safety margin to the dive, it brings more confidence in scuba divers and the dive team. Everyone knows if you increase your confidence the enjoyment of the dive goes way up. This is the reason we dive. Go enjoy the underwater world.

Article Source:

Kathy Dowsett

Wednesday, May 21, 2014

How to Do SCUBA Dive Calculations

By Edwin Thomas, eHow Contributor

One of the dangers of scuba diving is the absorption of nitrogen into the bloodstream, as too much nitrogen causes decompression sickness. For this reason, dive table calculations are taught in any basic scuba diving course. Through these calculations, a diver can track how much nitrogen her/his body has absorbed on a given dive, and therefore plan her/his time on the surface and her next dive within the bounds of safety.


Monitor your bottom time on your first dive, taking note of both the deepest depth and the time spent there. Either you or your dive buddy needs a dive watch to do this.

Round up the depth and time figures to the nearest 5 for safety and utilize these numbers to determine your nitrogen class on the dive table. A dive with 18 minutes of bottom time at 95 feet should be rounded up to 20 minutes and 100 feet, yielding a class of "F."

Monitor your surface interval, or the time spent between the first dive and the second dive of the day. Utilize this number to determine your new, reduced class. After two hours on the surface, you should have dropped to class "D."

Inquire about the maximum depth of the day's second dive and utilize this figure (rounded up for safety) to determine how much bottom time is safe for the second dive. If you spent two hours on the surface and the next dive bottoms at 65 feet, round up to 70 feet. In this example, the table indicates a maximum safe bottom time is 25 minutes and a residual nitrogen time of 20 minutes.

Add your residual nitrogen time to your actual bottom time to determine your new nitrogen class. With 20 minutes of residual nitrogen time and all 25 minutes spent on the bottom, your total nitrogen time is 45 minutes. Fed back into the table, this indicates a new nitrogen class of "I."

Repeat the procedure in Steps 3 and 4 to determine the safe diving parameters for a third dive.

Tips & Warnings

This guide is tailored to match the tables used by the National Association of Underwater Instructors (NAUI). Other organizations, such as the Professional Association of Dive Instructors (PADI) or Scuba Schools International (SSI) have their own tables, but all are based on almost identical principles. Adaptation to another organization's dive table should only require studying how the table is organized and not changing the calculation method.

Dive computers perform the same calculations and with greater accuracy. However, a given dive computer might use a more liberal margin of safety than others. Check a new dive computer's algorithm by comparing its results against those of your dive table calculations for the first few dives, just to see where the dive computer stands.

Thanks to Edwin Thomas, eHow Contributor

Kathy Dowsett

Monday, May 19, 2014

Hydration and Dive Safety

While you were taking your open water or other course(s), I'm sure the importance of hydration while diving was mentioned. But how much was it stressed? Everyone knows that being dehydrated is bad in general, but was the significance of hydration during scuba diving explained to you? Do you know why it's important to scuba diving specifically? Do you know how scuba diving itself dehydrates you faster than many other activities? Do you know the symptoms and what to do about it? If you do, great! If you're still unsure, then this article is for you.

How Does Dehydration Affect Scuba Diving?

To put it simply, dehydration predisposes divers to decompression sickness. (DCS) When the body is dehydrated, the blood thickens. The slower, thicker fluid makes it hard to transport necessary nutrients and exchange gasses. This diminished capacity for gas exchange is what directly affects scuba divers and increases risks for DCS. If the thickened blood can't adequately exchange gasses, then it can't adequately off-gas nitrogen. So even when diving within the limits of the tables or a computer, the dehydrated diver is at a greater risk. This isn't the only issue for scuba divers, though. Dehydration causes other physical side effects that can directly contribute to diver safety: muscle cramping and fatigue, increased heart rate and blood pressure, and confusion. None of those things are helpful to divers and all of them can lead to exhaustion, reduced air consumption, and poor decision making.

How Does Dehydration Happen?

Most of us know how dehydration happens at a basic level: You lose more water than you put in and you end up dehydrated. Simple, right? People think about hydration when they're heavily exerting themselves and sweating profusely. But those things don't happen all that often while scuba diving, so what makes divers dehydrate quicker than normal? How does it sneak up on you? Let's understand that hydration doesn't have to do with just water. Hydration involves a balance of water and electrolytes and it's surprisingly easy to throw off that balance. Let's look at some of the ways that are specific to scuba diving.


That sweating contributes to dehydration is no surprise. But people don't often realize how much they're actually sweating inside their wetsuits. Even if you're not roasting, if you're sweating at all outside the suit, you're sweating all over underneath it. Why? Because the suit doesn't allow for the body to cool by air evaporation, so it just keeps trying and trying. The longer you have that suit on out of the water, the more water and electrolytes you're losing due to sweat and you may not even realize it. Try to keep the suit off until right before you're getting ready to dive.


Yes, breathing dehydrates you. It especially dehydrates us as scuba divers. On land, we naturally lose some water during exhalation. Go breathe on a piece of glass if you're not sure what I mean. That condensation you see is water coming from your body. So if that happens to everyone, why is scuba diving special? Many people don't realize it, but one of the big jobs the lungs have is to humidify and warm up the air we breathe. The drier that air is, the more our lungs have to work to humidify it and as we all know, compressed air is extremely dry. On top of that, the colder the diving conditions are the more the lungs have to work to warm that same dry air, nearly doubling the effort and moisture loss. So every single breath we take from a compressed air tank, we lose water from our bodies, so much so that nearly a cup can be lost on a 30 minute dive just by the absolutely necessary task of breathing. Score one for the rebreathers on this issue because their air is warmer and more moist.


If you're like most people, you're diving somewhere warm and sunny. And if you're like most people, you don't get enough sun normally so you're probably getting sunburned on your dive vacation. Fluid loss occurs when the skin is burned and the body immediately sends fluid to the skin. The warm sun then evaporates that moisture and fluid is completely lost. Wear sunscreen and keep covered!


Another issue with scuba diving out on a boat in the middle of the ocean is wind. Generally riding in a boat involves wind of some sort, as does the ocean in general. Sweat and other moisture is evaporated by this wind and increases dehydration Salt Chances are the diving you're doing is in saltwater. The boat ride out to the dive site mists salt onto your skin, then you jump into the salty water, and afterwards you sit around with the dried saltwater on your skin. This water evaporates (thanks to the sun and wind) leaving behind salt crystals that leech the moisture directly out of our skin. Try to rinse off if fresh water is available.

Immersion Diuresis, aka Peeing in Your Wetsuit

Have you noticed that when you're diving you tend to pee a lot? This may erroneously lead you to believe that you're well hydrated when that may not actually be the case. When we jump into cooler water, blood is shunted from our limbs to our core in an effort to keep warm. In response to the inevitable increase in blood pressure, the body then starts flushing fluids. In addition to the cold, the water pressure also increases blood pressure, doubling the effect of the cold water. Both of these things directly affect scuba divers and result in divers urinating much more often than they should and losing fluids and salt. Obviously, this is a contributor to dehydration.


Whether it's from sea-sickness or partying, vomiting will severely dehydrate you from direct fluid and electrolyte loss. Try to manage sea-sickness if you can, and continue to try and drink water or sports drinks in between bouts. And even though you may be on vacation, if you're scuba diving try to minimize your drinking at the very least enough to keep yourself from praying to the porcelain god nightly.


Yes, you're on vacation. But if it's a dive vacation, drinking should be minimized. I'm not saying you can't have a couple cocktails once you're done diving for day, but too much alcohol is a very bad thing when diving. For one thing, alcohol is a diuretic which means it's going to make you pee more and we've already established that can be a bad thing. It also has a lot of sugar in it and when you drink things high in sugar, the body has to dilute them with water.

A good rule is for every drink you have, drink a glass of water. What I generally do is have an alcoholic drink, then a glass of water, then alcohol, so on and so forth. What this means is I don't get hungover and I don't get dehydrated because of the alcohol. Just an idea!

Symptoms of Dehydration

Now we've gone over the various ways divers get dehydrated, so how do you know if you are dehydrated? Some symptoms are very obvious, others maybe not so much.

Thirst (this is generally the first symptom)
Dark urine (ideally urine should be nearly clear - unless you're on certain medication, have specific medical conditions, or have eaten beets)
What Do You Do?

Well first off, what you do NOT do is drink gallons of water before or during your dive vacation. Too much water can have just as many hazards as too little. The key is just to remain habitually hydrated by drinking normal amounts of water at regular intervals prior to and during your vacation. And yes, water is your best choice.

Some sports drinks are good too, but remember they do have high sugar content which can counter some of the hydration you get. The bonus with sports drinks is that they help with replenishing electrolytes. But don't drink them in place of water, drink them in addition to water. Energy drinks contain a lot of sugar and caffeine, both of which are going to act against your hydration efforts, so best to stay away from them. Water, water, water.

Eating helps with hydration too. If the boat you're on offers you fruit wedges during the day, eat them because they contain water, vitamins and fructose. Some salty snacks will replenish electrolytes too.

Basically, if you do anything that causes fluid loss then you need to replace those fluids. If you get sunburned, you need to drink more water. If you're drinking a lot of alcohol, you need to drink more water. If you're vomiting, you need to drink more water. Get the idea?

Hopefully now you understand the reason that divers need to stay hydrated, how fluid loss occurs for divers, and how to fix it. We all want to have safe and healthy dive trips and vacations and proper hydration is part of that. Incorporate it into your next dive plan!

Shelley Collett ~ Freelance Writer ~ PADI Scuba Instructor

Kathy Dowsett

Tuesday, May 13, 2014

Canadian Shipwrecks

Sunken Ships/Shipwrecks

As long as man has gone to sea, there have been shipwrecks. A frequent cause in earlier times was simply losing one's way and running aground; but the failure of man's technology when pitted against the unforgiving sea also accounts for some of history's most infamous shipwrecks. The best-known example of this was the sinking on its maiden voyage of the SS TITANIC, the greatest technological achievement of its day. It went to the bottom after a brief encounter with an iceberg on a foggy April night in 1912, 320 nautical miles (600 km) off Newfoundland, with a loss of over 1500 lives.

Spectacular Wrecks

Canada has also had its share of spectacular shipwrecks including, most notably, the Canadian Pacific passenger liner SS EMPRESS OF IRELAND, which sank in 14 minutes in the GULF OF ST LAWRENCE after a collision off Rimouski on 29 May 1914. Of the 1477 passengers and crew, 1014 perished, a death toll exceeded to that point only by the Titanic incident. However, both the passenger list and the ship itself lacked the glamour of the SS Titanic, and the incident was soon forgotten in a world about to be engulfed in war.

SABLE ISLAND, a crescent-shaped sandbar 300 km east-southeast (160 nautical miles) of Halifax, is also infamous for its shipwrecks, and is known as "the Graveyard of the Atlantic," as its shifting sands have been the site of over 350 such incidents.

The sudden loss in 1975 of the modern US bulk carrier Edmund Fitzgerald, which went down in LAKE SUPERIOR with all 29 crew members during a November storm, was a more recent Canadian tragedy, again reminding us that modern ships are not unsinkable. Fortunately, shipwrecks are now infrequent, though, as the size and complexity of ships increase, a single wreck (and the resulting pollution clean-up in the case of tankers or chemical carriers) can be very costly. Just over 250 ships were reported lost from all causes in 1992, but this was out of a world fleet of over 80 000 merchant ships over 100 t.

Marine Archaeologists

Shipwrecks have long held a special fascination for many, including a new breed of MARINE ARCHAEOLOGISTS. The easy availability of scuba-DIVING apparatus has caused an enormous resurgence of interest in shipwrecks over the past 2 decades but serious archaeologists worry about the damage that amateur explorers and treasure hunters can cause to older fragile wrecks. Nonetheless, archaeologists and hobby divers are now finding many wrecks of historic interest in Canadian waters.

The remains of the vessels of Admiral Walker's British fleet, which was sunk in 1711, have been found off of Scatari Island, NS, and near English Point in the ST LAWRENCE RIVER. In LAKE ONTARIO, the British warships Hamilton and Scourge, which sank in a fierce storm during the War of 1812, have been found in 1973 and are now being protected. And in arctic waters are the remains of the BREADALBANE, which sank while involved in the FRANKLIN SEARCH.

Flotsam and Derelicts

In addition to a complete vessel which has sunk, run aground or burned usually being referred to as a "shipwreck," the terms "flotsam,""jetsam" and "derelict" are still used on occasion. "Flotsam" refers to the material or goods left floating on the sea as a result of a wreck, while "jetsam" is material intentionally jettisoned in an attempt to lighten the load of a sinking vessel. "Derelict" refers to any property, whether vessel or cargo, abandoned at sea without hope or intention of recovery. The term "wreck" also includes any part of a ship or boat, its equipment or cargo. In Canada, the laws governing the treatment of shipwrecks and marine salvage are embodied in the Canada Shipping Act, administered by the CANADIAN COAST GUARD.

Courtesy Historica Canada

Kathy Dowsett

Saturday, May 3, 2014

Diving in Rough Seas – When and how to dive in bad weather


First, just to make sure there are no misunderstandings: diving should be both fun and safe. If you’re ever in doubt as to whether a dive will be either, due to rough conditions, always err on the side of conservatism and cancel the dive. Never dive in a situation where you feel you’re outside of your dive skill range.

That being said, as you increase dive experience, the definition on non-divable conditions will change, as your increased skill and experience will make it possible for you to dive in conditions a newbie would not. To make diving safe in situations where the conditions are less than optimal, there are a few precautions you can take.


If the conditions are rough, the first thing you should do, unless you know your dive very, very well. Is to check with local divers and dive shops to get an idea of what conditions you can expect.

One thing is what the conditions are above the surface, but what you need to find out is what to expect below. Some places are less susceptible to rough conditions, and while the surface may see waves and strong wind, the dive site can be perfectly tranquil at only a few feet of water.

So find out by consulting the locals. What will it likely be like out there? Currents? Swells? When is the area non-diveable? What are you backup and exit options? If in doubt, ask a local divemaster to join you as a precaution.


Kathy Dowsett

Diving in rough seas, Great Inagua Island, Bahamas from YouTube