Yesterday, I had one of those deep and soul searching conversations with a very good friend. We were talking about work, the meaning of life and so on. In the course of the conversation we spoke about what brought us to diving.
In my case, I happened to get into diving by a series of unplanned but fortunate events. I signed up to do the open water class with a number of colleagues at work and just kept on doing classes. For one thing, I really enjoyed being in the water. I feel very comfortable and at home in the water. I think that the reason is that when I was a kid I spent many summer days at the local community pool trying to see how far I could swim underwater. I don't know why I had this desire to swim underwater, but I got fairly good at swimming underwater. However, the idea of SCUBA didn't cross my mind in the least. The closest I got to SCUBA was the fact that there was a small room in the pool complex with the sign "SUB AQUA CLUB" on the door. SCUBA just seemed so far out of reach.
The other factor that caused me to continue the classes was that I found the learning aspect challenging and opened up a whole new world to me. I have always enjoyed science and technology, so when I had to start learning about physiology and physics for diving, I was hooked.
In trying to explain what exactly it was that made me enjoy diving as much as I do, caused me to think about the my motivation and reasons for liking diving. The way I tried to explain it to my friend was to describe a man who walks down the street and unexpectedly finds very valuable article that changes his life. He didn't know the valuable article was there and was not looking for it, but having found it, caused him to experience many new things. I know it is an awkward word picture, but there are elements that are true for me.
My friend's experience was a little different to mine in that she got into diving in a more planned and organized way. She felt that she was not spontaneous enough in her approach to diving. Personally, I don't see her as being all that concrete and structured, but I guess she knows herself best. Everyone is different of course, so I am sure every diver has his or her own story about why they love diving.
The point of this post is that for the first time, I really sat down to think about why I am so passionate about diving and what keeps me so interested in the field.
Saturday, October 28, 2006
Friday, October 27, 2006
Squeeze the gas
Disclaimer: more dive master physics to follow. May not be suitable for the easily bored ;)
Today, we are going to take a brief look at what happens to a gas when you apply pressure to it.
The first thing to remember is that as the pressure on the gas increases, the volume of the gas will decrease in relation. In SCUBA diving we are very familiar with this from our very first open water classes. Most classes start off by talking about what happens when you take a flexible container of air down to 100 feet or so. Of course as every one probably knows, the air in the container will compress and the container will look like most of the air has been sucked out of it. Of course the air is still there, it is just that is has been compressed (squeezed by the pressure of the water).
Remember that the pressure multiplied by the volume is the same for a given container at any depth.
P1 x V1 = P2 x V2
The pressure multiplied by the volume at the surface will be the same answer as the pressure times volume at depth (for the obvious reason that as the pressure increases, the volume decreases).
Lets do a simple example to demonstrate the relationship and how it is used in dive master physics.
You take a container with the volume of 2 cubic feet (at the surface) to a depth of 66 feet. What will the new volume be.
Remember that 66 feet is equal to 3 atmospheres. So the 2 cubic feet at 66 feet will be compressed by the water pressure so that the gas inside the container will one third of that at the surface - 2 cubic feet divided by 3 (0.67 cu ft)
However, for the dive master exams the examiners try to be a little tricky so you have to read the questions very carefully. For example they might throw in the words "fresh water" into the question, which means you need to use 34 feet instead of 33 feet per atmosphere etc. Be sure to read the questions very carefully.
To make these pressure calculations more challenging, the examiners will ask you to determine what happens to a given volume of gas when you take it from one depth to another. It is not that the work is much harder, it is just that they seem to try to see if you are paying attention.
Lets do an example of a potentially trickier question. Note that we are now starting at depth and not the surface.
You need to take a volume of 20 cu ft from 99 feet to 66 feet in sea water.
First we need to calculate the original pressure at 99 feet - which calculate as 4 ata (p1).
Next we need to calculate the pressure at 66 feet - which is 3 ata (p2).
Remember the formula: p1 x v1 = p2 x v2
We have p1, v1, p2 but not v2. What we need to do is find out what v2 is. So to calculate the new pressure we use a ratio calculation
v2 = p1 / p2 x v1 (the slash is shorthand for divided by)
4 ata / 3 ata x 20 cu ft = 26.67 cu feet.
Of course in the dive master exams they will not give you easy numbers like these, but the principle is the same. Lets do a more realistic example.
15 cubic feet at 105 feet to 41 feet in fresh water.
v1= 15 cu ft
p1 = 105 ft / 34 (3.09 + 1 ata = 4.09 ata)
p2 = 41 ft / 34 (1.2 + 1 ata = 2.2 ata)
So lets plug the numbers into the ratio we used above
v2 = p1 / p2 x v1
v2 = 4.09 ata / 2.2 ata x 15 cu ft = 27.88 cu ft
The calculations are not difficult, but do remember the following key things
Make sure you know whether you are working with fresh water or salt water.
Make sure that you add in the surface atmosphere to get the ata pressure at depth.
Today, we are going to take a brief look at what happens to a gas when you apply pressure to it.
The first thing to remember is that as the pressure on the gas increases, the volume of the gas will decrease in relation. In SCUBA diving we are very familiar with this from our very first open water classes. Most classes start off by talking about what happens when you take a flexible container of air down to 100 feet or so. Of course as every one probably knows, the air in the container will compress and the container will look like most of the air has been sucked out of it. Of course the air is still there, it is just that is has been compressed (squeezed by the pressure of the water).
Remember that the pressure multiplied by the volume is the same for a given container at any depth.
P1 x V1 = P2 x V2
The pressure multiplied by the volume at the surface will be the same answer as the pressure times volume at depth (for the obvious reason that as the pressure increases, the volume decreases).
Lets do a simple example to demonstrate the relationship and how it is used in dive master physics.
You take a container with the volume of 2 cubic feet (at the surface) to a depth of 66 feet. What will the new volume be.
Remember that 66 feet is equal to 3 atmospheres. So the 2 cubic feet at 66 feet will be compressed by the water pressure so that the gas inside the container will one third of that at the surface - 2 cubic feet divided by 3 (0.67 cu ft)
However, for the dive master exams the examiners try to be a little tricky so you have to read the questions very carefully. For example they might throw in the words "fresh water" into the question, which means you need to use 34 feet instead of 33 feet per atmosphere etc. Be sure to read the questions very carefully.
To make these pressure calculations more challenging, the examiners will ask you to determine what happens to a given volume of gas when you take it from one depth to another. It is not that the work is much harder, it is just that they seem to try to see if you are paying attention.
Lets do an example of a potentially trickier question. Note that we are now starting at depth and not the surface.
You need to take a volume of 20 cu ft from 99 feet to 66 feet in sea water.
First we need to calculate the original pressure at 99 feet - which calculate as 4 ata (p1).
Next we need to calculate the pressure at 66 feet - which is 3 ata (p2).
Remember the formula: p1 x v1 = p2 x v2
We have p1, v1, p2 but not v2. What we need to do is find out what v2 is. So to calculate the new pressure we use a ratio calculation
v2 = p1 / p2 x v1 (the slash is shorthand for divided by)
4 ata / 3 ata x 20 cu ft = 26.67 cu feet.
Of course in the dive master exams they will not give you easy numbers like these, but the principle is the same. Lets do a more realistic example.
15 cubic feet at 105 feet to 41 feet in fresh water.
v1= 15 cu ft
p1 = 105 ft / 34 (3.09 + 1 ata = 4.09 ata)
p2 = 41 ft / 34 (1.2 + 1 ata = 2.2 ata)
So lets plug the numbers into the ratio we used above
v2 = p1 / p2 x v1
v2 = 4.09 ata / 2.2 ata x 15 cu ft = 27.88 cu ft
The calculations are not difficult, but do remember the following key things
Make sure you know whether you are working with fresh water or salt water.
Make sure that you add in the surface atmosphere to get the ata pressure at depth.
Tuesday, October 24, 2006
A little off topic
Earlier this week I listened to an interesting podcast on grammar (that statement sounds like a contradiction). What makes the podcast interesting is the way that it is presented. The podcast is called "Grammar Girl's Quick and Dirty Tips for Better Writing". For transcripts and more information take a look at her website. Grammar Girl has a fun and upbeat way of presenting her podcast. She has the wonderful ability to take what could be a dry and boring subject and actually make it interesting and memorable.
I have been listening to the grammar pod casts for a while and have picked up some good ways for remembering some grammar rules. For example, grammar girl gave a very memorable way of how to remember when to use whom (as opposed to who).
I am not sure how other blog writers go about writing their blogs, but as for me I try to make my blog entries interesting and informative, without being too dry. When I started writing this blog, I had a number of funny anecdotes that I wanted share. At first, I thought that the blog would be a good vehicle to sharpen my writing skills and be a place where I could write some of the interesting, and perhaps off-beat things that I notice in my little part of the world.
However, what I found was that I ran out of funny anecdotes and sometimes found it hard to come up with fresh and interesting topics. Last winter I went through a dry patch and had no desire to write blog entries. For one thing, I did not do any open water diving, and for another, just had no inspiration.
One lesson that I learned was that I need to pace myself. Too many blog entries in a short period of time has the effect of causing me to get burned out from writing. Although I really enjoy writing the blog, I find that if this becomes like a job or obligation, then it takes the fun and enjoyment out of it. I want to keep my entries fresh and interesting (at least to me).
So all this rambling brings me back to grammar girl. She mentioned something on her last pod cast about proofreading that actually gave me a fair amount of comfort and relief. Grammar girl wrote "So, given my long history with typos, it has become my belief that it's nearly impossible for someone to accurately proofread their own writing and be consistently successful." I have spent hours reading and re-reading my blog entries to try to catch the dumb typos that I know I make. I often forget to write your and write you etc. What grammar girl wrote helped me understand that I am not alone in the proofreading battle.
The thing is that I don't want to produce a perfect blog entry. That is not my intent at all. My intent is to make sure that I communicate clearly and don't have typos in my post that confuse the meaning of what I am trying to convey. My intention is to have fun with the blog and try to help other divers wherever I can. Hopefully the information I convey from time to time is useful and helpful. I try to walk a fine line between being informative, without giving so much information that it becomes boring.
I have been listening to the grammar pod casts for a while and have picked up some good ways for remembering some grammar rules. For example, grammar girl gave a very memorable way of how to remember when to use whom (as opposed to who).
I am not sure how other blog writers go about writing their blogs, but as for me I try to make my blog entries interesting and informative, without being too dry. When I started writing this blog, I had a number of funny anecdotes that I wanted share. At first, I thought that the blog would be a good vehicle to sharpen my writing skills and be a place where I could write some of the interesting, and perhaps off-beat things that I notice in my little part of the world.
However, what I found was that I ran out of funny anecdotes and sometimes found it hard to come up with fresh and interesting topics. Last winter I went through a dry patch and had no desire to write blog entries. For one thing, I did not do any open water diving, and for another, just had no inspiration.
One lesson that I learned was that I need to pace myself. Too many blog entries in a short period of time has the effect of causing me to get burned out from writing. Although I really enjoy writing the blog, I find that if this becomes like a job or obligation, then it takes the fun and enjoyment out of it. I want to keep my entries fresh and interesting (at least to me).
So all this rambling brings me back to grammar girl. She mentioned something on her last pod cast about proofreading that actually gave me a fair amount of comfort and relief. Grammar girl wrote "So, given my long history with typos, it has become my belief that it's nearly impossible for someone to accurately proofread their own writing and be consistently successful." I have spent hours reading and re-reading my blog entries to try to catch the dumb typos that I know I make. I often forget to write your and write you etc. What grammar girl wrote helped me understand that I am not alone in the proofreading battle.
The thing is that I don't want to produce a perfect blog entry. That is not my intent at all. My intent is to make sure that I communicate clearly and don't have typos in my post that confuse the meaning of what I am trying to convey. My intention is to have fun with the blog and try to help other divers wherever I can. Hopefully the information I convey from time to time is useful and helpful. I try to walk a fine line between being informative, without giving so much information that it becomes boring.
Monday, October 23, 2006
can you handle the pressure?
Disclaimer: these posts might not be suitable for people who have physica-o-phobia ;)
This is the next installment in the series on dive master physics. Today, I am going to write about how calculate pressure per at specific depths. There are some important things to remember when working with pressure. There are two types of pressure that is referred. There is absolute (ATA) and gauge pressure. The two very similar and it is very easy to confuse. Be very careful when reading the question to ensure that you know whether you are working with ATA or gauge.
The easiest way to remember the difference between the two is to think about what a gauge is. The gauge pressure is what you see on the pressure gauge. The other takes ambient (surrounding pressure) into account. So when the question asks you to determine ATA remember to always add in the ambient air pressure at sea level. Lets do a simple example to demonstrate the difference.
How much ata pressure is at 90 feet/30 meters?
90 feet divided by 33 = 2.73 atm + 1 atm = 3.73 ata
30 meters divided by 10 = 3 atm + 1 atm = 4 ata
Note that you always add the ambient pressure of 1 atm to the answer to calculate the ata pressure. So when you see "ata" think "add 1 atmosphere".
Gauge pressure is the same except that you don't add the 1 atm. The answer is what you see on the gauge. So when you see gauge - think what I see on the gauge.
Some other things to remember:
33 feet / 10 meters of sea water = 1 atm
34 feet / 10.3 meters of fresh water = 1 atm
Lets do another example.
What are the gauge and absolute pressures 67 feet / 22 meters in fresh water?
First calculate the atmospheres at depth
67 feet / 34 = 1.97 ata
22 meters / 10.3 = 2.14 ata
Remember that gauge pressure is what you see on the gauge so therefore the gauge pressures those we have just calculated.
To calculate the absolute pressure (ata) remember to add 1 atmosphere (the effect of the air column on the water). There the absolute pressures are
1.97 + 1 atm = 2.97 ata
2.14 + 1 atm = 3.14 ata
To add a little complication to the matter, the questions sometimes ask you to determine the psi or kg/cm2.
To do that you need to remember that 1 atm is equal to 14.7 psi (pounds per square inch) and 1.03 kg/cm2.
Imperial: 2.97 ata x 14.7 psi = 43.66 psia (pounds per square inch atmosphere)
Metric: 3.14 ata x 1.03 kg/cm2 = 3.23 kg/cm2
This is the next installment in the series on dive master physics. Today, I am going to write about how calculate pressure per at specific depths. There are some important things to remember when working with pressure. There are two types of pressure that is referred. There is absolute (ATA) and gauge pressure. The two very similar and it is very easy to confuse. Be very careful when reading the question to ensure that you know whether you are working with ATA or gauge.
The easiest way to remember the difference between the two is to think about what a gauge is. The gauge pressure is what you see on the pressure gauge. The other takes ambient (surrounding pressure) into account. So when the question asks you to determine ATA remember to always add in the ambient air pressure at sea level. Lets do a simple example to demonstrate the difference.
How much ata pressure is at 90 feet/30 meters?
90 feet divided by 33 = 2.73 atm + 1 atm = 3.73 ata
30 meters divided by 10 = 3 atm + 1 atm = 4 ata
Note that you always add the ambient pressure of 1 atm to the answer to calculate the ata pressure. So when you see "ata" think "add 1 atmosphere".
Gauge pressure is the same except that you don't add the 1 atm. The answer is what you see on the gauge. So when you see gauge - think what I see on the gauge.
Some other things to remember:
33 feet / 10 meters of sea water = 1 atm
34 feet / 10.3 meters of fresh water = 1 atm
Lets do another example.
What are the gauge and absolute pressures 67 feet / 22 meters in fresh water?
First calculate the atmospheres at depth
67 feet / 34 = 1.97 ata
22 meters / 10.3 = 2.14 ata
Remember that gauge pressure is what you see on the gauge so therefore the gauge pressures those we have just calculated.
To calculate the absolute pressure (ata) remember to add 1 atmosphere (the effect of the air column on the water). There the absolute pressures are
1.97 + 1 atm = 2.97 ata
2.14 + 1 atm = 3.14 ata
To add a little complication to the matter, the questions sometimes ask you to determine the psi or kg/cm2.
To do that you need to remember that 1 atm is equal to 14.7 psi (pounds per square inch) and 1.03 kg/cm2.
Imperial: 2.97 ata x 14.7 psi = 43.66 psia (pounds per square inch atmosphere)
Metric: 3.14 ata x 1.03 kg/cm2 = 3.23 kg/cm2
Saturday, October 21, 2006
Water weighs how much?
Yesterday, I bumped into one of the dive master candidates who recently completed his dive master classes. He was having all kinds of problems with the physics portion of the course and was lamenting his travails in trying to pass the exams. We will be getting together next week sometime to work on his physics and try to get him over the hurdle.
In the interim, I am going to review some of the most salient points in the physics for dive masters. What I would like to do is boil the issues down to the most critical ones. My intention is not to cover the entire physics portion, but to go over the parts that most students seem to have problems with. If anyone is interested in learning more about dive physics, physiology, equipment, I would highly recommend the PADI encyclopedia of recreational diving. There is a printed version and a version that you can install on your computer that includes videos etc. Again, the ERD is highly recommended.
So, why do we need to know how much water weighs? After all we are not going to haul water around.
Just about everyone knows that things seem to weigh less when submerged in water. So what is the reason and why is this important.
Water has the odd effect that it "pushes things up" to the extent that you are "pushing" water away for an object. For example if you put a SCUBA tank weighing approximately 40 pounds in the water it may feel like it only weighs a fraction of the actual weight. The reason is that the SCUBA tank displaces (pushes water away) to make place for the object.
So to determine how much the SCUBA tank weighs (or seems to weigh) in water, you have to know how much water has been displaced (pushed away). The amount is called the displacement volume. For example if the object we are putting in the water is one foot by one foot by one foot (a cube) then we know that the displacement volume is 1 cubic foot.
Next we need to know how much a cubic foot of water weighs. For example one cubic foot of sea water weighs 64 lbs and one cubic foot of fresh water weighs 62.4 lbs.
Now that we know how much the water "pushes back" we can determine what the effect of the push back is on the object we are putting in the water. Lets say the 1 cubic foot object weighs 100 lbs on the surface, we can find out how much the object will appear to weigh in the water. So the apparent weight is 100 lbs - 64 lbs = 36lbs.
This means that the effect of the sea water "pushing back" on the object will make it seem to only weigh 36 lbs.
Does this make sense?
Say for example you were asked by a friend to recover this 1 cubic foot object from the local quarry that you dive in. To do this, you will need to know how much lift you need to use to lift the object (how large a lift bag to use).
Right now the object is negatively buoyant by 36 lbs. Therefore we need to add extra lift to the object of at least 36 lbs to make it neutrally buoyant. To lift the object we will have to use a little more lift to make it positively buoyant to make it rise to the surface.
So we must again ask ourselves how much does water weigh to find out how much water we must displace (push away) to cause lift of 36 lbs. We know that 1 cubic foot of sea water weighs 64 lbs, so to displace 36 lbs we have to displace 36 divided by 64 which is approximately 0.56 cubic feet. So to make the object neutrally buoyant, we need a lift bag that can be inflated with at least 0.56 cubic feet of air. In other words we need to displace at least 0.56 cubic feet of sea water to provide enough lift to make the object neutrally buoyant.
I hope that this is fairly straight forward. I tried to boil the issues down to the most essential in calculating displacement and how much lift is needed.
Lets do another example for practice.
Lets say you need to recover a motorboat engine that weighs 400 lbs. The engine displaces 3 cubic foot of water.
So lets see what we know. The engine displaces 3 cubic feet of water and the weight of the displaced water is: 3 cubic feet x 64 lbs = 192 lbs. To find out what the apparent weight is we subtract the weight of the displaced water from the weight of the engine: 400 lbs - 192 lbs = 208 lbs. In other words the object appears to only weigh 208 in the water (or: it is negatively buoyant by 208 lbs).
Next we need to determine what size lift bag we need to lift the engine. Since we need to provide at least 208 lbs lift we need to displace 208 lbs of sea water: 208 lbs divided by 64 lbs = 3.25 cubic feet.
In the interim, I am going to review some of the most salient points in the physics for dive masters. What I would like to do is boil the issues down to the most critical ones. My intention is not to cover the entire physics portion, but to go over the parts that most students seem to have problems with. If anyone is interested in learning more about dive physics, physiology, equipment, I would highly recommend the PADI encyclopedia of recreational diving. There is a printed version and a version that you can install on your computer that includes videos etc. Again, the ERD is highly recommended.
So, why do we need to know how much water weighs? After all we are not going to haul water around.
Just about everyone knows that things seem to weigh less when submerged in water. So what is the reason and why is this important.
Water has the odd effect that it "pushes things up" to the extent that you are "pushing" water away for an object. For example if you put a SCUBA tank weighing approximately 40 pounds in the water it may feel like it only weighs a fraction of the actual weight. The reason is that the SCUBA tank displaces (pushes water away) to make place for the object.
So to determine how much the SCUBA tank weighs (or seems to weigh) in water, you have to know how much water has been displaced (pushed away). The amount is called the displacement volume. For example if the object we are putting in the water is one foot by one foot by one foot (a cube) then we know that the displacement volume is 1 cubic foot.
Next we need to know how much a cubic foot of water weighs. For example one cubic foot of sea water weighs 64 lbs and one cubic foot of fresh water weighs 62.4 lbs.
Now that we know how much the water "pushes back" we can determine what the effect of the push back is on the object we are putting in the water. Lets say the 1 cubic foot object weighs 100 lbs on the surface, we can find out how much the object will appear to weigh in the water. So the apparent weight is 100 lbs - 64 lbs = 36lbs.
This means that the effect of the sea water "pushing back" on the object will make it seem to only weigh 36 lbs.
Does this make sense?
Say for example you were asked by a friend to recover this 1 cubic foot object from the local quarry that you dive in. To do this, you will need to know how much lift you need to use to lift the object (how large a lift bag to use).
Right now the object is negatively buoyant by 36 lbs. Therefore we need to add extra lift to the object of at least 36 lbs to make it neutrally buoyant. To lift the object we will have to use a little more lift to make it positively buoyant to make it rise to the surface.
So we must again ask ourselves how much does water weigh to find out how much water we must displace (push away) to cause lift of 36 lbs. We know that 1 cubic foot of sea water weighs 64 lbs, so to displace 36 lbs we have to displace 36 divided by 64 which is approximately 0.56 cubic feet. So to make the object neutrally buoyant, we need a lift bag that can be inflated with at least 0.56 cubic feet of air. In other words we need to displace at least 0.56 cubic feet of sea water to provide enough lift to make the object neutrally buoyant.
I hope that this is fairly straight forward. I tried to boil the issues down to the most essential in calculating displacement and how much lift is needed.
Lets do another example for practice.
Lets say you need to recover a motorboat engine that weighs 400 lbs. The engine displaces 3 cubic foot of water.
So lets see what we know. The engine displaces 3 cubic feet of water and the weight of the displaced water is: 3 cubic feet x 64 lbs = 192 lbs. To find out what the apparent weight is we subtract the weight of the displaced water from the weight of the engine: 400 lbs - 192 lbs = 208 lbs. In other words the object appears to only weigh 208 in the water (or: it is negatively buoyant by 208 lbs).
Next we need to determine what size lift bag we need to lift the engine. Since we need to provide at least 208 lbs lift we need to displace 208 lbs of sea water: 208 lbs divided by 64 lbs = 3.25 cubic feet.
Sunday, October 15, 2006
Contemplation
As I write this post, I am sitting at the local lake that we do all our dive training in. A kind soul as left a wireless port open for us to use and fortunately I able to get Internet access here.The weather turned out to be fairly nice for this time of the year and right now it is sunny with a light cool breeze. The air temp is probably around 50f or so, and that is the best it has been all week. I didnt plan on coming out to the lake today, but was talked into it by a dive buddy who has an out of town friend visiting.
The out-of-towner have never used a drysuit and and has also not experienced our bracing temperatures at this time of the year. So I duly brought out my drysuit, thermal underwear etc. and help my dive buddy and her friend get set up etc. I think the out-of-towner will either love the cold water or hate it. I guess there is no real way to prepare someone for the cold bracing water. So far they seem be having a good time. They came back for extra weight, since the out-of-towner could not descend. I think it might be a case of the breathing too hard, but, but I got him squared away with an additional 6lb.
It is so serene out here. I lit a large fire and we are going to grill some meat when they come out of the lake. Even though the conditions are not ideal by a long shot, it is still good for the soul be out here, enjoying a late fall day.
The lake is placid surrounded by trees on all sides. The leaves have started to change color and there is an explosion of color all around us. In the lake there are three dive flags reflecting the warm afternoon glow and a few pontoons around with some fisherman trying to coax a few fish to take their bait.
What an excellent day this has turned out to be.
The out-of-towner have never used a drysuit and and has also not experienced our bracing temperatures at this time of the year. So I duly brought out my drysuit, thermal underwear etc. and help my dive buddy and her friend get set up etc. I think the out-of-towner will either love the cold water or hate it. I guess there is no real way to prepare someone for the cold bracing water. So far they seem be having a good time. They came back for extra weight, since the out-of-towner could not descend. I think it might be a case of the breathing too hard, but, but I got him squared away with an additional 6lb.
It is so serene out here. I lit a large fire and we are going to grill some meat when they come out of the lake. Even though the conditions are not ideal by a long shot, it is still good for the soul be out here, enjoying a late fall day.
The lake is placid surrounded by trees on all sides. The leaves have started to change color and there is an explosion of color all around us. In the lake there are three dive flags reflecting the warm afternoon glow and a few pontoons around with some fisherman trying to coax a few fish to take their bait.
What an excellent day this has turned out to be.
Tuesday, October 10, 2006
Stingray City
The Sydney Morning Herald reports that tourism to the world famous Stingray City has dropped by at least 40%.
"Watersport operators on the Grand Cayman Island in the Caribbean, are
reporting a drop in tourist numbers of up to 40 per cent with many locals
attributing the decline to the death of Steve Irwin (Sydney
Morning Herald)"
In August of this year (2006), I was fortunate enough to visit Stingray City. I was able to be the first one off the boat and got to spend at least 10 minutes with the Stingrays on my own while waiting for the rest of the divers. It was one of the most memorable experiences of all my dives. The Stingrays were so graceful and gentle and the visibility was excellent since no-one had kicked up any sand as yet.
As the dive progressed, the dive master started to hand feed the Stingrays and the other divers started to touch and pet the Stingrays. Personally, I do not like to touch the marine life so I just observed spellbound.
Like all things in this world, perception is almost as important as fact. The fact is that one is more likely to be injured by all kinds of things than being injured by a Stingray. What happened to Steve Irwin was a complete freak accident. However, I do understand the apprehension of casual divers and snorkelers toward Stingrays.
On the one hand, I am opposed to hand feeding the Stingrays, but on the other hand, Stingray City was one of my most memorable dives. I am a little conflicted about the interaction with the Stingrays in Grand Cayman, but since they have been doing Stingray City dives, there has been an excellent safety record.
The bottom line: lets continue to dive safely and responsibly, taking all reasonable precautions, but let us not stop enjoying the wonders of the sea because of one isolated incident.
Sunday, October 08, 2006
Last open water class for the season
This past weekend, I conducted two open water classes at the local spring-fed lake. The visibility was the best that I have seen all year and the water temp was on the cool side, but not too bad. I actually managed to enjoy the dives. Once you get used to the cooler water (let's say south of 60f) its not all that bad. I know that folks who are used to the 80f plus temps of the warmer climates will probably think that I have lost my mind, but I find the colder water oddly comforting. I cannot explain it, but I actually enjoy the sensation of the cold water against my skin. I suppose it is a matter of mind over matter.
The students did exceptionally well. I was one happy instructor. Even though the water was cold for the students, and the weather not too great, they did not complain and completed the certification dives and I believe had some fun along the way.
Today, as we came out of the water after the fourth certification dive, I noticed that the wind had picked up significantly and it looked like it might rain. So I asked the students if they would be willing to go over to a local Perkins restaurant to have some hot chocolate and complete the paper work. Everyone thought that it would be a good idea to go, so after packing up all the gear we headed over to the Perkins in a long convoy of vehicles.
What I did not consider was that the after-church lunch-time crowd would be there too. The manager was quite grumpy and was rather unfriendly and brisk. I did not really care for his attitude. No matter what I asked him, he would shake his head and come up with with a reason why what I was asking for would be a major inconvenience for him. Too bad, since I have taken a number of groups there before.
However, for the future, I have found a much better option. One of the students suggested that we go down to the local Target store and sit in the cafeteria to do the paper work. I was disappointed since I wanted to drink something hot (like hot chocolate) and wanted to buy everyone a round of hot drinks. In any event, we convoyed to the local Target and I was very happy and surprised to see a Starbucks inside the store, co-located with the cafeteria. I could not have been happier. We got to have a round of lovely hot drinks while I signed logbooks etc. We had a great time chatting, drinking our hot drinks and getting to know each other a little better.
What a wonderful way to end the open water diving season!
The students did exceptionally well. I was one happy instructor. Even though the water was cold for the students, and the weather not too great, they did not complain and completed the certification dives and I believe had some fun along the way.
Today, as we came out of the water after the fourth certification dive, I noticed that the wind had picked up significantly and it looked like it might rain. So I asked the students if they would be willing to go over to a local Perkins restaurant to have some hot chocolate and complete the paper work. Everyone thought that it would be a good idea to go, so after packing up all the gear we headed over to the Perkins in a long convoy of vehicles.
What I did not consider was that the after-church lunch-time crowd would be there too. The manager was quite grumpy and was rather unfriendly and brisk. I did not really care for his attitude. No matter what I asked him, he would shake his head and come up with with a reason why what I was asking for would be a major inconvenience for him. Too bad, since I have taken a number of groups there before.
However, for the future, I have found a much better option. One of the students suggested that we go down to the local Target store and sit in the cafeteria to do the paper work. I was disappointed since I wanted to drink something hot (like hot chocolate) and wanted to buy everyone a round of hot drinks. In any event, we convoyed to the local Target and I was very happy and surprised to see a Starbucks inside the store, co-located with the cafeteria. I could not have been happier. We got to have a round of lovely hot drinks while I signed logbooks etc. We had a great time chatting, drinking our hot drinks and getting to know each other a little better.
What a wonderful way to end the open water diving season!
Tuesday, October 03, 2006
Divemaster fun
There are two students in my current divemaster class. They are naturals in the pools and it has been a lot of fun working with them on the various skills that we have cover. Last night, I sprang a surprise on them. I have a non-diving friend who was visiting me and I suggested to him that he accompanies me to class and be a discover scuba student for the evening.
The two candidate divemasters had to walk my friend though all the steps of setting up the gear. He didn't have to set up any of the gear himself, but just had to watch and learn. The candidates did a fantastic job. One of the candidates has a great way of explaining concepts in every day terms and makes even seemingly complex things seem easy and understandable. They seemed to really enjoy the unexpected challenge.
The advantage that I could see was that they had an actual person to demonstrate the skill to which probably made it more realistic for them. In any event, they will make excellent instructors one day.
The two candidate divemasters had to walk my friend though all the steps of setting up the gear. He didn't have to set up any of the gear himself, but just had to watch and learn. The candidates did a fantastic job. One of the candidates has a great way of explaining concepts in every day terms and makes even seemingly complex things seem easy and understandable. They seemed to really enjoy the unexpected challenge.
The advantage that I could see was that they had an actual person to demonstrate the skill to which probably made it more realistic for them. In any event, they will make excellent instructors one day.
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