No news on the diving front.
I've been in Sacramento for a week an a half. I considered diving while I was out here, but I decided to hang out with friends over the weekend.
Here are my last log entries, which brings the blog up to date.
DIVE 1 (North End of Delray Reef):
Water Temp: 86 Max Depth: 64 FSW Average Depth: 54 FSW Current: Mild Southward. We dropped right between the Delray and Boynton Reef system. Vis was top to bottom. Thin layer of cooler water flowing over the reef. Buoyancy was good. Not great. Only used my hands (for swimming) twice. Saw two large barracuda. One large lionfish (why oh why don’t we have a spear...) Tons of tropicals of course, including a huge midnight blue parrotfish.
Dive # 25
PSI start: 3400
PSI end: 800
Bottom Time: 49 minutes
Bottom Time to Date: 15:18
Buddy: Krista Camp
DIVE 2 (Boynton Ledges):
Water Temp: 86 Max Depth: 68 FSW Average Depth: 54 FSW Current: Mild-Moderate Southward. Current got stronger through out the dive. Vis was still great, probably around 100’. We worked north along the ledge, against the flow. Great dive for my buoyancy. I felt completely in control at all times. Trim was good. No sculling. Yay. Saw a tiny moray eel in a hole (around three inches long), found a huge lobster, who was not to shy. If I had a fishing license, he/she would have been dinner. Highlight was a large school of 3’ish barracuda Cutting across the reef from west to east about 10’ in front of me. Great dive.
Dive # 26
PSI start: 3400
PSI end: 800
Bottom Time: 42 minutes
Bottom Time to Date: 16:00
Buddy: Krista Camp
Wednesday, August 25, 2010
Sunday, August 15, 2010
I love SAC...
So, I was sitting around the other day doing big important things. Okay, fine, I was really browsing the internet looking at diving things. I ran across a great blog post on gas planning. And no, not the kind of gas planning where you give your partner a surprise by ripping one under the covers.
The blog is written by Doppler @ The Decostop you can find it here: Gas Planning Part 1
Even though his blog is written about topics mostly for wicked awesome tech divers, gas planning can benefit everyone, and it gets more important the deeper you get, i.e. do I really have enough gas to get my buddy and I back to the surface after 30 minutes at 90 feet on an AL80?
There are a few ways to plan for gas consumption. I am a big fan of Doppler's method, which involves finding out your resting surface air consumption, then modifying for depth, and work rate (which you guesstimate initially, and fine tune with experience). The other method I know of involves tracking your gas consumption over a series of dives, and calculating off this. You can find an excellent write up of that method here: NWGratefuldiver's Gas Management
I like the "Doppler" method better, but both are good, and are orders of magnitude above nothing at all. The reasons I prefer Doppler's way is that it gives you a true resting SAC. I, for instance, was sitting on the couch watching soccer while I breathed of my reg for thirty minutes. If you do this...get a towel. You just don't notice the drool under water! The other method only gives you a working SAC which is going to be an amalgamation of the conditions in which you dove. I suppose you could come up with different working SAC rates for different conditions, but this seems less elegant.
Here is a quick overview of the formulas (don't get scared math haters, if I can do it you can do it):
Cylinder Baseline (this allows you to convert from PSI to cubic feet, and back): Volume of Tank (cf)/ Working pressure. So, an HP 100 would be 100/3442, which gives you 0.029. This means that there is .029 CF in every PSI of the tank. So, to convert PSI into CF, you multiply by the baseline. To convert CF into PSI you divide by the baseline. Easy.
Volume Used: PSI/ Baseline. Shows how many CF used for the PSI consumed.
Consumption per minute: Volume Consumed (PSI)/ Time. For instance, in my test below, I consumed 7.08CF over thirty minutes sitting on the couch. Or, .24 cubic feet per minute.
Consumption Estimate adjusted for time, depth, and work: SAC in minutes * (depth in feet / 33 + 1)* Time in minutes * Work rate) So, for instance, using my SAC at 54 feet deep planning for 50 minutes at a work rate of two gives me .24(54/33+1)*50*2=63.273, but in the interests of being conservative with the stuff that keeps me alive, we'll call it 64CF. If you got a different answer, you should google "order of operations".
So, there you go, my explanation of gas management. Now, here is my log entry for my SAC test:
8/10/10 - SAC Test
Did resting SAC test. 30 minutes on an LP 85, consumed 200 PSI. Service
pressure: 2400 PSI. Baseline: .0354 CF/ PSI. 30 minutes at surface=
7.08 CF. CF/Min. = .24 CF/min.
Plan for Captain Tony. Max Depth 87 FSW. Breathing EANx 32
Bottom Time: 32 Minutes. Work factor 2.0 .24*(87/33+1)= .87 CF/ Min at depth * 32 = 27.93 CF. Work Factor of 2 = 55.86 CF Bottom. Ascent from 87 FSW to 15 FSW @ 30 FPM = 2.4 minutes, average depth of 51 FSW. 2.93 CF. Safety stop @ 15 FSW = 2.1 CF. Ascend to Surface @ 30 FPM, average depth 8 FSW = .30 CF
Bottom: 56 CF. Ascent: 3 CF. Stop: 2 CF. Ascent 2: 1 CF. Total
gas needed= 62 CF.
Gas Recap for HP100 (baseline .029): 62CF with 38 CF in reserve. Turn Pressure: 2476 Ascent Pressure : 1510. Pressure at stop: 1499. Pressure after stop: 1491 Pressure on surface: 1487.
Note that in the interests of greater reserves, I rounded up (generally). I also planned the dive for consumption at the Max depth of 87 feet, although, that is right on the sand at this site, so I probably would be 5-6 feet shallower, but planning for max depth, again, gives me extra reserves.
In the interest of getting a more accurate work factor, I would have noted my pressure after 16 minutes. If it was less than 2476, obviously I would have underestimated, and would need to shorten my dives to keep adequate reserve gas. I could then modify my work factor appropriately for future dives in similar conditions.
The blog is written by Doppler @ The Decostop you can find it here: Gas Planning Part 1
Even though his blog is written about topics mostly for wicked awesome tech divers, gas planning can benefit everyone, and it gets more important the deeper you get, i.e. do I really have enough gas to get my buddy and I back to the surface after 30 minutes at 90 feet on an AL80?
There are a few ways to plan for gas consumption. I am a big fan of Doppler's method, which involves finding out your resting surface air consumption, then modifying for depth, and work rate (which you guesstimate initially, and fine tune with experience). The other method I know of involves tracking your gas consumption over a series of dives, and calculating off this. You can find an excellent write up of that method here: NWGratefuldiver's Gas Management
I like the "Doppler" method better, but both are good, and are orders of magnitude above nothing at all. The reasons I prefer Doppler's way is that it gives you a true resting SAC. I, for instance, was sitting on the couch watching soccer while I breathed of my reg for thirty minutes. If you do this...get a towel. You just don't notice the drool under water! The other method only gives you a working SAC which is going to be an amalgamation of the conditions in which you dove. I suppose you could come up with different working SAC rates for different conditions, but this seems less elegant.
Here is a quick overview of the formulas (don't get scared math haters, if I can do it you can do it):
Cylinder Baseline (this allows you to convert from PSI to cubic feet, and back): Volume of Tank (cf)/ Working pressure. So, an HP 100 would be 100/3442, which gives you 0.029. This means that there is .029 CF in every PSI of the tank. So, to convert PSI into CF, you multiply by the baseline. To convert CF into PSI you divide by the baseline. Easy.
Volume Used: PSI/ Baseline. Shows how many CF used for the PSI consumed.
Consumption per minute: Volume Consumed (PSI)/ Time. For instance, in my test below, I consumed 7.08CF over thirty minutes sitting on the couch. Or, .24 cubic feet per minute.
Consumption Estimate adjusted for time, depth, and work: SAC in minutes * (depth in feet / 33 + 1)* Time in minutes * Work rate) So, for instance, using my SAC at 54 feet deep planning for 50 minutes at a work rate of two gives me .24(54/33+1)*50*2=63.273, but in the interests of being conservative with the stuff that keeps me alive, we'll call it 64CF. If you got a different answer, you should google "order of operations".
So, there you go, my explanation of gas management. Now, here is my log entry for my SAC test:
8/10/10 - SAC Test
Did resting SAC test. 30 minutes on an LP 85, consumed 200 PSI. Service
pressure: 2400 PSI. Baseline: .0354 CF/ PSI. 30 minutes at surface=
7.08 CF. CF/Min. = .24 CF/min.
Plan for Captain Tony. Max Depth 87 FSW. Breathing EANx 32
Bottom Time: 32 Minutes. Work factor 2.0 .24*(87/33+1)= .87 CF/ Min at depth * 32 = 27.93 CF. Work Factor of 2 = 55.86 CF Bottom. Ascent from 87 FSW to 15 FSW @ 30 FPM = 2.4 minutes, average depth of 51 FSW. 2.93 CF. Safety stop @ 15 FSW = 2.1 CF. Ascend to Surface @ 30 FPM, average depth 8 FSW = .30 CF
Bottom: 56 CF. Ascent: 3 CF. Stop: 2 CF. Ascent 2: 1 CF. Total
gas needed= 62 CF.
Gas Recap for HP100 (baseline .029): 62CF with 38 CF in reserve. Turn Pressure: 2476 Ascent Pressure : 1510. Pressure at stop: 1499. Pressure after stop: 1491 Pressure on surface: 1487.
Note that in the interests of greater reserves, I rounded up (generally). I also planned the dive for consumption at the Max depth of 87 feet, although, that is right on the sand at this site, so I probably would be 5-6 feet shallower, but planning for max depth, again, gives me extra reserves.
In the interest of getting a more accurate work factor, I would have noted my pressure after 16 minutes. If it was less than 2476, obviously I would have underestimated, and would need to shorten my dives to keep adequate reserve gas. I could then modify my work factor appropriately for future dives in similar conditions.
Saturday, August 14, 2010
Hurray for advanced open water!
Well, hurray for doing it anyway.
I'm going to be honest, I don't much see the point in AOW. I'm not saying you don't learn things in it. I try to learn and practice a bit on every dive. That said, I know (for the most part) where I am as a diver and what I need to work on. My training plan is Cavern > Intro to Cave, then after a bit at this level, Advanced Nitrox & Decompression Procedures, leading to Apprentice> Full Cave.
AOW doesn't really do anything for me there. But, hey, now I can dive the Vandenburg without a divemaster...
I took AOW with Dayo Scuba in Winter Park, FL. My girlfriend, Krista ( a two legged diver), and I were the only ones in the class, so that was cool.
Here are my logs from the second day:
8/6/10- AOW, DeLeon Springs, FL
Navigation Dive. Need more practice navigating, maintaining depth, and counting kick cycles. Maximum Depth 20’. Vis around 40 feet. Water 73f
Dive # 22
Bottom Time :30
Bottom Time to date: 13:29
Buddy: Krista Camp
Instructor: TJ, Dayo Scuba
8/6/10- AOW, DeLeon Springs, FL
Peak Performance Buoyancy dive. Good buoyancy. Need to be mindful to not scull. I know I don’t need to do it, but when my hands have nothing else going on, I do it subconsciously. Maximum Depth 25’. Vis around 40’. Water 73f.
Dive # 23
Bottom Time: 30
Bottom Time to date: 13:59
Buddy: Krista Camp
Instructor: TJ, Dayo Scuba
8/6/10- AOW, DeLeon Springs, FL
Search and Recovery Dive. Fun. Moved block with a lift bag. Then poked my head in the cavern entrance. Very strong flow. It keeps hundreds of empty snail shells ‘floating’ in the current in a small cut of rock. I poked my head in and saw the stop sign. No grim reaper. Disappointing. Maximum Depth: 28’ Vis around 40’. Water: 73f.
Dive # 24
Bottom Time: 30
Bottom Time to date: 14:29
Buddy: Krista Camp
Instructor: TJ, Dayo Scuba
I'm going to be honest, I don't much see the point in AOW. I'm not saying you don't learn things in it. I try to learn and practice a bit on every dive. That said, I know (for the most part) where I am as a diver and what I need to work on. My training plan is Cavern > Intro to Cave, then after a bit at this level, Advanced Nitrox & Decompression Procedures, leading to Apprentice> Full Cave.
AOW doesn't really do anything for me there. But, hey, now I can dive the Vandenburg without a divemaster...
I took AOW with Dayo Scuba in Winter Park, FL. My girlfriend, Krista ( a two legged diver), and I were the only ones in the class, so that was cool.
Here are my logs from the second day:
8/6/10- AOW, DeLeon Springs, FL
Navigation Dive. Need more practice navigating, maintaining depth, and counting kick cycles. Maximum Depth 20’. Vis around 40 feet. Water 73f
Dive # 22
Bottom Time :30
Bottom Time to date: 13:29
Buddy: Krista Camp
Instructor: TJ, Dayo Scuba
8/6/10- AOW, DeLeon Springs, FL
Peak Performance Buoyancy dive. Good buoyancy. Need to be mindful to not scull. I know I don’t need to do it, but when my hands have nothing else going on, I do it subconsciously. Maximum Depth 25’. Vis around 40’. Water 73f.
Dive # 23
Bottom Time: 30
Bottom Time to date: 13:59
Buddy: Krista Camp
Instructor: TJ, Dayo Scuba
8/6/10- AOW, DeLeon Springs, FL
Search and Recovery Dive. Fun. Moved block with a lift bag. Then poked my head in the cavern entrance. Very strong flow. It keeps hundreds of empty snail shells ‘floating’ in the current in a small cut of rock. I poked my head in and saw the stop sign. No grim reaper. Disappointing. Maximum Depth: 28’ Vis around 40’. Water: 73f.
Dive # 24
Bottom Time: 30
Bottom Time to date: 14:29
Buddy: Krista Camp
Instructor: TJ, Dayo Scuba
Off with a whimper...
So, I'm not well known for keeping up with things. But I figured, hey, I already keep a log of my dives in a little blue (severely water damaged) book, why not share it with the world? I'm important.
For a little bit about me, I started diving in 1994, although I spent almost all of my summers skin diving before then. After a break during which I lost a leg below the knee (I hate you cancer...) I took a refresher course and started diving again this year.
Living in Central Florida, I have access to a ton of different dive types. Right now I am focused on increasing my skills, and starting down the cave diver certification path.
For a little bit about me, I started diving in 1994, although I spent almost all of my summers skin diving before then. After a break during which I lost a leg below the knee (I hate you cancer...) I took a refresher course and started diving again this year.
Living in Central Florida, I have access to a ton of different dive types. Right now I am focused on increasing my skills, and starting down the cave diver certification path.
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