Today, David Snyder talks about his goal of losing weight for diving.
Is this some “Biggest Losers” program? Ah, no. Lose weight when you go diving refers to you kit (equipment). As we continue to dive, over time we acquire more and more things. Very important things when we acquired them but are they still important?
The second path of my weight loss quest is to change heavier for lighter. Ounces add up to pounds. Do you really need a 12″ knife when a 6″ knife will do just fine. Lights, if your light is more than three years old you should be able to double the capacity or half the weight with a new one. I look at each piece of equipment to see if there is a lighter or more capable substitute.
My goal for this process, is one bag 40 pounds, two weeks of diving, nothing rented (except bottles) or borrowed. I am getting there.
How much do you weigh?
Blog
Underwater Camera Maintenance
You may have heard the saying that underwater photographers like to tell new photographers, it is not if your housing will leak, it is when. And while there may be some truth in that phrase, there are ways to reduce your risk.
Here are some things you can do to keep your camera in working order:
- Before you leave town, assemble your camera so you make sure you have all of the parts. It is a lot easier to locate missing items while you are at home rather than on your trip.
- Check your spare parts kit. You should have a spare set of o-rings for your camera housing, ports, cables and strobes. It should also include the appropriate lubricants for the o-rings, an eraser to clean contacts and some contact cleaner. Don’t forget spare batteries, cables, cards and Moisture Muncher® packets.
- One of David Snyder’s suggestions is to store a set all of the tools you need to assemble your housing and strobes in your camera bag or box. This allows you to assemble everything without having to find your diving tool kit.
- Develop a packing check list so you make sure you have everything. I developed one for our group traveling to Antarctica and you are welcome to use it too.
- When you arrive at your destination, take time to carefully assemble your camera. Remember, be methodical when you are working with your camera. Clean all the o-ring seating surfaces (requires you remove the o-ring from the groove. Grease your o-ring according to the housing manufacturer’s guidelines and before you close-up the housing, check the o-ring and the seating surfaces one more time. I had a client who flooded a camera because of a beard hare that broke the seal on his o-ring.
- After your dive, it is important to rinse and dry the camera. It is better to leave it in a water bath until you are ready to deal with it. However, one word of caution, leaving it in the boats rinse tank may result in a leak because the motion of the boat may break a seal especially on cameras with ports or waterproof lenses (Nikonos Camera).
- I recommend creating a work surface using a Microfiber Towel. These handy towels keep parts from bouncing away and absorb any moisture that may be on the camera. Use a separate towel to dry the camera and clean the sealing surfaces. You want to keep all saltwater away from the seals and sealing surfaces. The salt crystals that remain after the water evaporates may cause a leak.
- Again, whenever you open the housing, be methodical about cleaning and checking the o-rings. You may not have to open all of the o-ring protected areas between dives but, if you break the seal, you need to re-prepare the o-rings, sealing surfaces and grooves.
- As a note, before you seal the camera in the housing, add a Moisture Muncher® to absorb the condensation typically caused by the heat generated by the camera and battery.
- As you start your descent, check your housing for bubbles and for any signs of leakage.
If you are careful, your inevitable flood may be minor or even delayed for years and years.
Dave Talks About Rebreathers – The Basics, Part 1
Todays’s post comes from David Snyder, Technical Rebreather Instructor. David answers some questions about rebreather diving which show the basics of rebreather diving.
Q: Do you need a specific class for a specific type of rebreather?
A: Yes, the physics and physiology is the same for all units but each rebreather is different, hence specific classes.
Q: How do you know when it is time to change your scrubber material? Is this a problem with divers trying to get more out of the material then they are suppose to?
A: You track the dive time on the scrubber media and change it per the manufacturer’s recommendation.
Q: What I am now curious about is, you said on a CCR, at 60ft your PO2 is 1.3. Wouldn’t that figure limit your depth, or do you have the ability through out the dive to adjust that percentage? And if that is the case, is it that ability that gets divers into trouble?
A: You dial the set point in and that is then constant, independent of depth. You asked, if you descend won’t the PO2 spike? It would except that because of Boyle’s Law the volume in the loop will decrease as the pressure increases and you will need to add diluent to the loop. This has the effect of negating the spike. As you ascend you vent gas from the loop and O2 is added to maintain the set point.
Q: Is it better (more flexible) and safer to be able to manually inject O2 right into the breathing loop, or is it better to have it done automatically?
A: Since you retain the ability to manually add gas in all units, some divers will adjust the set point lower than their target and then “fly the unit manually” and use the eCCR controller as a backup. With some units this is easier than others. All eCCR training covers this procedure.
Q: Okay, how the heck did you come up with .59 PO2 at 60 feet? If pressure at sea level is 14.7, and the air we breath is roughly 80% nitrogen, and 20% O2, if I then multiply 14.7 x .2= 2.94, would that be the PPO2 at the surface,
A: Now let us remember back to our Nitrox class. Dalton’s Law, the sum of the partial pressures equals the total pressure. At the surface PO2 = .21 and PN2 = .79 for a total of 1.0. This is then 1 ATA. Therefor at 33fsw ATA would be 2. Because of Dalton’s Law, PO2 would be .42 and PN2 would be 1.58. At 66fsw the ATA would be 3, there for PO2 would be .63 and PN2 would be 2.37. The formula to convert depth to ATA is (Depth / 33) + 1.
Now for 60ft the ATA would be (60/33)+1 or 2.8. Since the ratio of O2 to N2 is the same no matter the depth PO2 would be (2.8 * .21) or .59. It is easiest to convert depth to ATA then calculate the PO2 and PN2 as needed.
Scuba Diver's Social and Birthday Party!
Oceanic Ventures is having a party! If you did not know it, Oceanic Ventures turned 20 in December and we wanted to have a party to celebrate! Join us on 19 January 2011 at 6:30pm for a very fun party and pig roast. Tickets are required and must be purchased in advance. We would love to see all of our old friends and our new friends as well. Bring your favorite diving photographs from your Oceanic Ventures trip. Details are on the party page or contact Ashton for more details.
Bring a non-diving friend and show them how much fun we can be out of the water.
I hope you will join the Oceanic Ventures Staff at the party!
Eric's Cozumel Winter Get Away January 13-17 2011 Announced
Yeah!!! Eric’s January trip details are completed!!!
We are holding air, boats and space; so, join us for an escape from the cold to Cozumel. We will be staying again at Casa Mexicana, located in town, close to shopping, dining, and activities. We have a full diving schedule starting with a boat dive the day we arrive, then one day of three dives, two days of two tank diving with lunch on the boat each day. Opportunities to add additional afternoon or night dives as desired. Recreational equipment can be rinsed and stored at the dive shop. Breakfast buffet is included each morning.
This trip is open to recreational, technical and rebreather divers. For rebreather and technical divers, the run times for each dive will be two hours.
This trip promises to be a fun trip and a great time to escape the cold in Houston or wherever you live. Dive Mom is holding space so you need book onto the trip in a hurry becasue we have to release the air seats we are holding. You can find out more details about this fun trip to Cozumel by calling Ann or reviewing the detail trip sheet.
