Sunday, November 24, 2013

A Decent Descent

I spend a lot of time talking to divers about neutral buoyancy, but what about negative and positive buoyancy?  These two states are equally important to the diver yet I feel that their value is often underestimated, so allow me to post a two part blog.  This week let’s dissect a descent.

Obviously, at the start of a dive, a diver wants to be negatively buoyant.  That means a diver must change his volume by deflating his buoyancy compensator.   Before he does anything, though, if you are in a wetsuit, you want to let water into your suit.  You have to warm up that layer of water anyway and doing this at the beginning of your dive will force out any air trapped in the suit.  Next, vent air from our BC’s and exhale. It is important to know where the BC dump valves are.  If they are at the shoulder, the diver should start upright in the water, thereby forcing all the air to the shoulders of the BC, near the dump valves.  He pulls his dump cords, holding them open long enough to vent all the air, and then as he starts to go underwater, he hugs himself to make a streamlined silhouette.  Some BC’s are made with the dumps farther down the back of the vest so the diver can dump in a more horizontal position, but air can be dispelled from these BC’s even if the diver is upright, by holding the inflator hose above the head and depressing the vent at the end.  As with all equipment, it is the diver’s responsibility to figure out how everything works.   

After venting air from the BC and exhaling and assuming the diver’s weights are correct, he should float slowly beneath the water’s surface like a leaf, not a cannonball.  At this point, only a foot or so underwater, if the diver takes in a big breath of air, he will pop right to the surface.  This is where many divers start demanding added weight, which is only a mask covering poor technique.    As we learned in our open water course while trying to perfect our fin pivot, good buoyancy can only be achieved with patience, so the key here is to slow down.   Once a foot underwater, with his entire breath expelled, the diver should take a small breath in and then expel it as though blowing out birthday candles. To facilitate the descent, the diver should also keep his fins still.  Remember that fins are powerful and if they are beneath you and in motion, they will work against the descent.   I like to start with my fins pointing straight down (toes pointed), so I am like a pencil pointing to the bottom.  The diver should also keep his arms at his side, or crossed in front of him, to stream line his profile and reduce drag.

As the weight of the water crushes the exposure suit and any air remaining in the BC, the rate of descent increases.    This is the point where some divers are rolled onto their backs by the weight of their tanks.  They start finning and flailing until they either work themselves to the surface or crash to the bottom, destroying the visibility.  If the diver finds himself falling to his back, one solution is what Mike calls “Stop, drop and roll” (though  the steps are not really in that order).  Stretch out your legs and stop moving.  Do a “log roll” so your tank is on top of you again and you are in a more horizontal position.  The horizontal position will produce drag and therefore slow your descent.  Then continue your “drop,” finning to the planned depth. 

Another way to manage the this phase of the descent, is to start from the “pencil” orientation, then once the descent is underway, slowly bend your knees while leaning slightly forward and flair your fins wide and to the side.  This creates some drag to slow the descent and gives me more stability.  If you sense continued increase in descent speed, add a quick blast of air to the BC.  Wait a beat or two, and if the descent is still too rapid, add another blast, and so on until you are descending at the rate you desire.  The goal is to arrive at the planned depth neutrally buoyant.

The descent seems like it should be the easiest skill to master in the open water course, but to do it correctly, a diver must put some effort into perfecting it. It is really worth the effort to make your diving as enjoyable as possible.  It will also go a long way to help a diver to conserve his air.  As with all sports, however, the key is practice, practice, practice!

Tune in next week when I will be dissecting the ascent!

Sunday, November 17, 2013

What is stopping you?

Since I have my winter and spring trips just about finalized, I am diligently researching where I want to be diving in summer 2014 and winter and spring 2015.  I feel like I live from dive to dive sometimes!   Of course my family, job and other land activities do keep me busy, but I don’t let my busyness get in the way of my favorite leisure activity/stress reliever. While I recognize that not everyone will be as passionate about the sport as I am, I still wonder how it is that other divers aren’t making more of an effort to dive at least often enough to their skills sharp?

Is it lack of gear?  Minimally, every student diver should invest scuba quality mask, fins and snorkel.  When I have a student who does not purchase these basic pieces of gear, or buys a cut rate set, I know that that person will not dive after the course is finished.  I wonder then why they invested the money and time in the course in the first place.  Beyond those items, scuba gear can be rented.  In fact, renting gear can give a diver a good idea of the style gear they prefer, and what feels the best while diving.  If they really like something they’ve rented several times, they can usually purchase the item at a substantial discount compared to new.  In addition, if they buy from a reputable dive shop, they will know what the maintenance record of the item and whether parts are still available for future repairs and maintenance, thus avoiding the hidden pitfalls of eBay or other online “bargains”.

Is it cost of gear?  I know that when people stop in the shop to inquire about diving, they often are shocked at the cost of a full set-up, BC, Reg, wetsuit, etc., but why?  If a person was to get into hunting, for example, they would most likely buy a rifle with a scope for $400-$1000, and at least one box of ammo, $40(or two if they would like to practice before actually going out into the wild).  A blaze orange coat and bibs would go for about $250, not to mention boots, gear for gutting the deer and many other items: all that for a once-a-year activity.  Learning to play a musical instrument is another example.  Instruments can be rented for $35 per month and a student usually pays $45 for a 30 minute lesson weekly, not to mention, music.  The true cost of that pursuit adds quickly!  Don’t even get me started on the cost of golf!   Many worthwhile hobbies require an upfront investment in gear, but scuba is certainly not the most cost intensive.

Is it the cost of outings?  Can’t be!  For a little gas money and $20 a person can have a fun filled day exploring any number of inland quarries in the area.  Lake Michigan is home to a number of famous wrecks that can be explored by even relatively new divers.  If you are used to diving in the ocean, freshwater diving may not seem as exciting, but with a little research on local destinations, a diver can find plenty to keep his interest.  The fun in activities can also come from the people you are with.  Outings with Team Manta are about having laughs, helping one another, sharing ideas and experiences and learning new things.  After the dives, it is about ice cream or a dinner with friends.  Group travel to tropical destinations can be fun, too, without the stress of having to investigate and coordinate the details of getting there, where to stay and who to dive with.

Is it the lack of a dive buddy?  That is another good reason to go with a dive group.  We usually think of a buddy team as being two divers, but it can just as easily be a trio.  In a group, you are very likely to find someone who matches your level of expertise or shares your interests and who knows?  You may find a regular dive buddy. 

Is it lack of time? That is a frequently used excuse, but in reality it does not hold water!  The tropical trips are planned and advertised nearly a year in advance, giving plenty of time to plan vacation and save up money.  Summer outings are published on the Manta Divers web calendar at least in March, of not earlier.  What it takes is for the diver to make a commitment.  Take out a pen and write it down: “I am diving this weekend.” (And this one and this one…) 

When Mike and I were first certified, we invested in gear to give us the freedom to dive when we wanted.  We made a commitment to do at least a full week of diving every year and have been rewarded with some wonderful experiences, and a vastly varied group of friends.  At the time, we were in the dark about all the wonderful diving opportunities right here in our back yard, so I made it my mission as a dive instructor and shop owner to promote both distant and local dive spot.  I do whatever I can to get my divers out there using their skills.  I doubt I will ever be setting around at the home wishing that I had spent less time diving.  Rather, I believe that I will always bemoan the fact that I started diving too late and never got enough dives in!  How about you?

Sunday, November 10, 2013

Math: The Diving Edition

Everyone enjoys playing volleyball with bowling balls at Haigh, so I thought it would be fun to find something like that but soft to play with in the pool.  The trouble is, finding something that will be negatively buoyant, but not too negative, so when I came across a small 10lb. medicine ball on clearance at Dick’s, I wondered if it would fit the bill.
Lift Bag by Sheryl

In chapter one of the open water manual, we all learned that things are neutrally buoyant if they displace an amount of water that equals the weight of the object.  So if I figure out the volume of the ball, I would be able to find out if it will sink and the degree of negativity.

I measured the circumference: 23in. 
Volume Sphere =  π *diameter3 ÷ 6    
Diameter = circumference ÷ π, so 23in. ÷ 3.14= 7.32 in. diameter.  
THEN,   π*7.323/6=205.6 in3 is the volume of my medicine ball. 
Converting to ft3=205.6/1728= 0.12ft3
A cubic ft. of freshwater weighs 62.4lbs. 

So: 62.4lbs./1ft3 =  X/0.12ft3 = 7.49lbs. displaced. 

Then, 10lbs.(weight of ball)-7.49lbs.(weight of water it displaces) = 2.51lb negative buoyancy for my ball.

Now, I know that I could have just put it in the water to see if it floated, but this was a good exercise.  When doing underwater recovery, or just a job in which we need to move a heavy object underwater, knowing how to calculate displacement saves a bunch of trial and error.  It also helps when you want to sink something.  You need to figure out how much positive buoyancy the object has in order to know how much weight to add.  It is kind of like what I go through with new divers to estimate the amount of lead they will need to sink.

So now you have an idea what I am doing in the off season!

Sunday, November 3, 2013

Six Things: Six Scuba Movies (Say that five times fast!)

Wisconsinites know that winter can be an awfully cruel season, but divers, unless they are into ice diving, or have unlimited funds for dive travel, take the long cold stretch of the season harder than most. One thing that helps me get through the cold nights is curling up with a good (or campy or bad) scuba movie.  So, here are six selections I like(in no particular order):

Sanctum: Scary in its realism.
For me, this one fits in nicely with other horror films, in addition to being one of the few diving movies that does not use sharks as their instrument of fear.  It taps into the fear of extreme overhead environments and exploring them.  Cave diving is a highly specialized skill and when in an unexplored cave, let alone underwater in an unexplored cave, there are many ways to die, and Sanctum touches several of them.   In this film, which was inspired by actual events, a world renowned cave explorer is looking for the way to get from the opening of Esa’ala cave in New Guinea, to its exit into the sea.  It teaches lessons such as, “It is not good to take short cuts,( like neglecting to bring bail out bottles)”, and “Don’t dive if you are not fully up to the task,” and remember all your training, even stuff like “free flow regulator breathing.”  I think this one is technically pretty authentic. 

Thunderball: James Bond thriller
Seeing the remnant of the sunken plane used in this film is what inspired Mike and me to learn to dive.  In addition, if you were wondering where they came up with all the crazy characters in the first Austin Powers movie, viewing Thunderball will make it all clear.  In this classic James Bond film starring Sean Connery, the dashing Bond must outwit  Spectre’s Number 1 in a race to retrieve two atomic bombs somewhere under the Bahamian waters.  Among the cool Bond gadgets is a tiny mouth held scuba tank, and a jetpack.  Again, plenty of bikini clad women and brushes with sharks keep the plot moving.

The Abyss: Science fiction with aliens.
During the cold war, an American nuclear sub mysteriously goes on the fritz and sinks several hundred feet into the ocean and on the edge of the abyss.  Believing that the Reds must be involved in this mishap, a Navy SEALS team is deployed to salvage the sub’s missiles, but that they must get help from the diving crew on a deep water oil drilling rig nearby.  The intrepid crew soon realizes that the Reds are the least of their worries as they find themselves in a fight to stop WWIII.  At one point though, Ed Harris and the crew are trying to revive a drowned Mary Elizabeth Mastrantonio using breaths and defibrillation only techniques.  So no one on this mission has proper first aid training? Lots of scary special effects in this Sci-Fi thriller.

The Life Aquatic with Steve Zissou : Comedy
Steve Zissou (Bill Murray) is sort of a Jacque Cousteau character, but grief stricken and on a quest to avenge his best friend’s death by killing a fluorescent shark.  It has its funny moments.  Also starring in this film are Angelica Houston, Owen Wilson, Jeff Goldblum and Willem Dafoe.  This movie inspired the Team Manta tuque.  I am still looking for the right speedo, though!  

The Deep Blue Sea  : Science fiction without aliens.
  (clip about the making of this film)

This movie can’t miss with the like of Samuel L. Jackson, LLCool J, Saffron Burrows and Michael Rappaport.  In this film, a group of scientists are working on a cure for Alzheimer’s disease, using shark brains.  The bad thing is that in the process, they made the sharks smarter, and are they teed off that someone’s been fooling with their brains!  Lots of great special effects, but it is fun to look for mistakes.

See if you can spot these!

Lady in Cement: Campy detective movie
This is a great one with Frank Sinatra, Rachel Welch and DAN BLOCKER (Jeeze, he looks huge next to Sinatra!).  I love these movies from the day when scuba was new and the sea so dangerous and full of mystery.  Back then, scuba was for only those interested in an early death. Everyone wore shiny black neoprene and giant coffee can size masks.  Sharks were everywhere: impossible to avoid, but no worries.  The diver need only stab him with his knife and that shark is history!  This is a fun one for it’s classic detective vibe. 

What are your favorite scuba movies?  20,000 Leagues Under the Sea? Into the Blue with Jessica Alba? The deep with Nick Nolte?  Finding Nemo?