Archive for the ‘Tech / Advanced’ Category

This time I brough the camera!

Friday, September 23rd, 2011
Nuidbanch

Nuidbanch

Too often, I’ve had some fantastic diving experiences but can only share them with words.  California is one of those experiences.  I have sworn to myself that I will never again dive without a camera.

Here on the east coast our shore is composed of white sandy beaches.  Great for sunbathers, but not much to look at for divers.  Other coasts have rocky shores.  On rocky shores, fish have places to hide, plants have places to take root.

The west coast enjoys these rocky shores.  Kelp anchors to the seabed, and a variety of sea life thrives in it’s shelter.  While east coast diving is all about shipwrecks, west coast divers can simply drop in the water and enjoy diving the kelp beds.

Last week I had another opportunity to dive California’s underwater forests.  On my first trip to CA, my 35 mm film camera failed me, and I came home with only memories.  My last trip, I was involved in  some intensive training, and did not bring the camera.  This time, I was taking pictures one way or another.

The reason for the trip revolved around training, again.   This time I was working on an instructor cert on the new KISS GEM pSCR.   After diving the unit for many weeks in our local quarry, I felt comfortable in it’s operation.  Now I had to teach others.  My IT set up the class that involved system operation, buildup, pool and open water.  The first portions went quickly, and we were soon discussing open water.

Point Lobos

In the Monterey area, there are many options for open water dives.  After a few discussions, the decision was on Point Lobos, a small peninsula south of Carmel.  The area is mostly state park with some fantastic vistas.  Shore entry is in a small lagoon with a facility for divers.  Upon arrival we were greeted by local divers, and quickly discussed conditions prior to their second dive.  Our entry was uneventful, and we were soon swimming through the kelp beds.  There is no comparable feeling in Northeast diving.

The next day Alan borrowed a friends boat, and we headed to the Monterey marina breakwater.  I’m sure there are better placed to dive, but on my last visit we saw many Rainbow Nudibranchs close to the breakwater.  We have no such creatures here in the Northeast, so I expressed my fascination, and desire for a picture.

While preparing the boat and gearing up, we observed a number of large red jellyfish floating near the surface.  I gathered as many photos as I could on the surface, and anticipated seeing them in the water.  After a quick boat trip and back roll entry, we headed down to find the anchor a few inches from a line Alan placed a few years earlier.  Over on the breakwater we heard the Sea Lions barking above us and the shrimp crackling in the rocks.  Between drills and sea lion fly byes, Alan helped me snap a few shots of the abundant flora and fauna.

After the class, I spent my preflight surface interval photographing the topside environment.  Seals, sea lions, pelicans, … all posing for the tourist.  It was a great trip with lots of things to learn.  If you ever have the opportunity to visit, I highly recommend getting wet.

Spring in the Pool

Saturday, June 25th, 2011
OW Class

OW Class

When our local shop asked if I could lend a hand with classes this spring, I had no idea what I was in for.

Lately, I’ve only been teaching technical and CCR classes.  These students usually have many dives under their belt, and are looking to take the next step beyond recreational diving by honing their skills, learning new ones and expanding their dive planning and preparation.

It was fun working with newer students that were just learning their dive skills.  Since I was assisting where needed, I had the opportunity to work with a number of classes; Open Water, Advanced, Specialties, Rescue…  Then, to top it all off, the shop had nine Diver Master Candidates this spring.

I must admit, to having a lot more fun than expected.  There are always some new students that struggle with simple skills like mask clearing and U/W gear donning.  However, they’ve never done it.  We all struggled with those skills.  Once we learned how it’s done, and had some time to practice, our fear faded.  That’s when we can relax and enjoy the adventure of diving.  This is exciting to see and be around.

Technical diving involves more complicated skills that are much more demanding.  Some of my Tech students joke that I enjoy torturing them.  Not so.  The skills are required by the standards.  Once learned and practiced they become second nature, and can get you out of a bad situation.  Again, that’s when we can really enjoy the adventure.

To all those students that kept me in the pool and up at Dutch, dive safe, practice your skills, and look me up when you need a dive buddy!  Now I’m off to go diving!

How Long can a Scuba Diver Stay Underwater?

Sunday, January 30th, 2011

I provided a simple answer to this question in a post last winter.  Over the past year, this post received a large number of hits, so it’s obviously this is a question that is often asked.   Therefore, I wanted to expound on the previous post.

There is no short answer to this question.  Ultimately, the limiting factor is either available gas, or environment.   The environmental factor here is cold.  Water transfers heat 25 times faster than air.  Even 80 degree water robs your body of heat.  This is why exposure protection is needed.  For the rest of this discussion, let’s assume there is sufficient exposure protection for the given water temperature.

Now the time limit is just a function of the available gas.  Let’s breakdown the answer based on type of diver.

Free Diving: Here the divers plunge to some amazing depths on one breath of air, and stay for several minutes before returning to the surface.  The limiting factor is the individuals tolerance for low Oxygen, and high CO2. I believe the current record is 124 M unassisted.  The maximum duration for static (resting) breath hold is 11 minutes 35 seconds.

Basic Scuba Diving: Here there are two limits:  The available gas in the diver’s tanks, and the no decompression limit for the depth.   There is a detailed explanation of the factors involved, but an average diver can stay between 60-80 ft for about an hour.

Technical Diving: Divers are limited by the number of tanks they use during the dive.  Some exceptional dives have been for over 18 hours.  Clearly a great deal of planning is required for these types of dives.  More routinely Technical Divers often go to 150-250 ft with durations around 90-120 minutes.

Rebreather Diving: A rebreather (as described here) removes the gas limitation, but imposes a limit on the duration of the scrubber material.  Based on the construction of the rebreather, this is usually between 3 and 11 hours.  The limiting factor here is the number of tanks a diver is willing to bring in case of rebreather failure.

Commercial Diving: These divers are provided gas from a surface vessel or station.  This technique also referred to as surface supplied, does not have a limit on the gas available.

Saturation Diving: In this case the divers body is completely saturated with inert gas.  In some cases the divers will utilize a habitat between dives.  This provides an area where the diver can warm up, and take food and liquids.  In essence there is no limit to the duration that a diver can live in saturation.  The down side is the extremely long time needed to decompress.

I hope this helps answer the question.   If you have any questions on this subject, send me a comment below.

Notes on Diver Etiquette

Monday, November 15th, 2010

The other day, I found myself in a discussion with a group of instructors and experienced divers over the issue of diver etiquette.  Everyone agreed that this varies wildly from diver to diver, and shop to shop.  While there is no explicit place for this discussion in the training curriculum, it is a subject that should be brought up.   We all agreed the best time to teach this is as part of the Open Water class (teach good habits before divers learn bad ones).  Many of us do include a few minutes to discuss this in class, then try to reinforce the concept during the open water dives.

Unfortunately, there are other instructors that do not understand the need, do not have the time, or just have bad etiquette themselves.

Ultimately, a diver’s etiquette will reflect their own personality.   A diver that only thinks of them self, will never follow good etiquette.   Someone that is considerate of others will try their best to be considerate while diving.  However, many of the latter do not know how to do this as new divers.  Here are some points to consider.

  1. On the surface:
    In many dive locations, gear space is limited.  This is especially true on dive boats.  Being conscience of this and trying to minimize the space we use is good etiquette.  Here are some points to consider on a dive boat.  These points also apply to other dive sites, but boats are usually the most space limited.

    • Gear boxes and bags. Try to keep gear containers no larger than necessary.   Try to bring containers that fit neatly under benches.  Divers showing up to a boat with over sized bags or too many bags are being inconsiderate of others, and will often get glares or rebuke from the crew. I recommend three containers:
      1. One for the BC and dry / wet suit
      2. A small one for dry gear.  A backpack works for me  (phone, towel, snacks, a few spare parts …),
      3. A small crate (about the size of a milk crate) for misc Scuba gear (reel, lift bags, lights… with fins on top)
    • This configuration works well in most environments of the North East.  On a boat, the crate  should fit well under the bench where you are setting up your tanks.  The drysuit goes in a dry location until needed.  The backpack is always in a dry location.
    • Put gear away promptly. Once your gear is loaded, set up your tank and stow your gear neatly out of the way.  The same is true after a dive.   As you take your gear off put it back into your crate and stow it neatly out of the way.  Not only is this good etiquette, but it can prevent gear damage or loss on a busy deck.
    • Dive Planning: Keep in mind that your not the only one on the boat. I recall several occasions where the entire boat was waiting over half and hour for one customer to finish his dive. If you plan on doing longer dives, then try to get into the water quickly.
    • Clean up after yourself: It’s amazing to see how much debris is left after the divers remove their gear from a dive boat. Half empty water bottles, cans, partially eaten bags of food … Yes, the crew will clean the boat, but all of this is in everyone’s way during the trip too.
  2. Gearing Up This is a process that takes up both space, and time. Here are some items to consider when working to don our gear in limited space.
    • Timing: If you know that you take longer than others to gear up, then either start gearing up early, or wait for others to go first.
    • Lend a hand: If you decide to wait for the diver next to you, then give them a hand.  That way they are out of your way quicker.
    • Be self sufficient:  This takes some time to learn, and practice. Most boat crews are eager to help in any way they can. However, there are often a lot of divers gearing up at once. Before strapping on tanks, prep the gear so that it is in reach as you don your kit. Watch an experienced crewmen.  Most can gear up with no assistance.   Again, it’s not that assistance is unavailable, but if you need lots of help, then you’re preventing other divers from getting any.
  3. Underwater: This can be difficult, since it’s not easy to know where other divers are in relation to yourself.  However, here are a few items to keep in mind.
    • Look around you. There may be other divers near you that you’re not expecting.   This is especially true on or near the up-line.  Be careful of your finning when you know other divers are near.  Fin slowly until you know your not going to kick a fellow divers.
    • Steer clear of classes. If you see an instructor working with a class, try to keep a reasonable distance.  Otherwise, you may confuse and distract the students from following their instruction.   Also, additional divers in close proximity makes it difficult for the instructor trying to keep watch over his students.
    • Photo ops: This is more of an issue in warm water diving, but keep in mind that other divers may want to take a picture also.  I’ve had video footage ruined by a diver sticking his fin in view while recording.  On the other hand, I try not to take too long, and let the next photographer get a chance.
    • Reels: Keep your line reel low and secure.  On several dives, the wreck looked like spider web with lines draped here and there.  Near the up-line it’s important to tie your reel low and put wraps close to the wreck.  A line 10 ft off the wreck can become an entanglement hazard as it is out of an approaching divers view.  When passing across another line, pass your line underneath.   Assuming your on your way out, the other diver should be on his way back before you, and will not be delayed by your line.

Conclusion:

Again, many of these points apply anywhere, not just to dive boats.  Any time space is limited, we need to work to make maximum use of it.

These were some of the points our group discussed.  Let me know if you have others.

Count the Counter lungs

Tuesday, October 12th, 2010

A friend just asked an interesting question:  Why have two counter lungs vs one?

I must admit, that no one ever told me an answer to this question, but here is my reasoning for 2 vs 1:
One counter lung only lets the scrubber work during half of the breathing cycle.
If the lung is on the exhale side, then it inflates on exhale, but gas only passes through the scrubber on inhale.
If it’s on the inhale side, then gas passes through the scrubber only on the exhale.

If you have two counter lungs, half the gas passes through the scrubber as you exhale, and half passes through as you inhale. This makes the gas pass through the scrubber slower, (aka dwell time)  and therefore the scrubber is more effective.  I would also assume that the slower gas movement would decrease the work of breathing of the unit.