Any Scuba Divers?

Yeah, I know what you mean about zero to hero... some people I wouldn't want to be on the same boat with are starting their instructor course this week! I have heard that they have improved a lot but would still rather not risk it.

I'd be tempted to do the BSAC thing but would have to retrain myself to dive their way... for instance, I dive a hog looped twin set and that's a bit bsac no no but it is what I am used to, most comfortable with and will not change it as I think it works very well. I also don't have a car so would be crap at the pay it forward aspect of the club.

I dive with Scimitar out of Portland. I like their crew, conscientiousness and the fact that I can go from the Hotel Aqua, across the parking lot and I'm there LOL.

I've not done fish and chips on the harbour cos I tend to stay on the island (and am not a huge fan of fish and chips) which is lucky... I have enough bad food habits to more than make up for it! LOL

LOL Sometimes I find it fun to put on a single and remember when I thought that was heavy. I'm still doing my DM training so get to wear a single when doing that. I don't own a 12l any more but have kept my bcd and single reg set.

A friend of mine has just taken up free diving and she loves it! After years of diving and doing all up to tech instructing she is loving exploring a new way of diving - which is less expensive than the rebreather she wants.

I'm thinking of giving it a go at some point as well but have too much on my plate right now.

Are you on YD by any chance?

I am a SCUBA Diving Instructor in Egypt, and I can tell you why the energy used while scuba diving is so high. There are 2 reasons:

1.) Your body temperature is 98.6 F (37 C), so even while diving in tropical waters where the water temperature is 80 F (~27 C), even though the water is warm, it is still taking heat from your body, because the water temperature is sill much less than your body temperature. Plus being submerged for some time reduces your core body temperature, so if you are making 2 or 3 dives per day, you get cold much faster on each successive dive. And if you dive multiple days in a row, doing repetitive dives, then each successive day your body is working over time to stay warm, even for hours after diving.

2.) Your body is working much harder under increased barometric pressure than you think. Even if you were to go just sit on the sea floor in 65 feet (20 meters),and do nothing but sit there, your body is burning a lot of energy to resist the pressure. Each 10 meters is +1 atmosphere of pressure, so at 20 meters, the barometric pressure is triple what it is on the surface. At 20 meters you are in 3 atmospheres of pressure. Your body adapts to this pressure naturally and you don't feel it.

Add to these to factors, that you are swimming while carrying a lot of weight, (45 - 55 lbs between your weight belt and tank), plus on the surface before and after the dive, and also maybe walking a bit, climbing the boat ladder, and for each hour of Scuba diving you burn the same amount of energy as 1 hour of running.

I am reviving this thread rather than starting a new one. I was very surprised that MFP said 90 minutes of SCUBA diving expended 736 calories. This is about the same as an hour of vigorous lap swimming. That can't be. As another comparison, I was on a stationary bike doing an intense interval workout today for 32 minutes, my pulse was up to and over the peak range during the strenuous part, and the machine told me I expended 300 calories. There's no way 90 minutes of diving is the same energy expenditure as an hour of high intensity interval training.

In general I try to use very little effort when diving. Aside from extending dive time from being easy on the air, it's advised NOT to do strenuous activity while diving or 24 hours afterwards to reduce the chances of getting decompression sickness (DCS). In the case of my dives yesterday, I actually was working. I'm a dive volunteer at a non-profit aquarium. Some of our tasks do take effort. But nothing like swimming laps or getting to peak heart rate on a cardio machine. In fact, as breathing rate goes up, the regulator can only give so much air, and it can get kind of panicky. Been there, done that. You just have to relax and breathe a minute or two and things get better. For tech divers using rebreathers at depth, it's extremely dangerous to have increased breathing rate due to partial pressure of gasses. It can be quickly fatal. I'm not a tech diver.

I searched at Divers Alert Network (DAN) to see if they had published any data on caloric effort from diving. No luck. I wonder where the estimates on MFP came from. Anybody know?

I wear a drysuit with a warm undergarment. Even in 45 degree water, I stay fairly warm unless I'm not doing any activity. My fingers get cold sometimes. Effort or not, there's usually dampness on the exterior of my undergarment up against the inside of the drysuit. Perspiration happens. It's nothing like what I sweat out on the cardio machines. No way.

I find it interesting that there are 14 different choices for bicycling (seven each for actually riding and for stationary bikes). There's ONE entry for SCUBA, free diving, and snorkeling. I think that it would be possible to link caloric effort to air consumption. When I download data from my dive computer, the Oceanic software calculates a Surface Air Consumption (SAC) rate. It normalizes the gas you use at any depth to what you most likely would have used on the surface. All else being equal, an experienced diver with good buoyancy control will have a lower SAC rate than a new diver. That new diver will be doing more work. For a given diver, especially an experienced one, the SAC rate increases as effort increases. An example; three weeks ago I did a 54 minute dive that wasn't very energetic. I slowly moved along the bottom following another diver. My SAC rate was 0.505 cuft/min. A second 50 minute dive was more energetic; hovering around 12 feet deep near the tunnel watching for sharks while a working diver cleaned the acrylic. My SAC rate for that dive was 0.627 cuft/min. My dives yesterday were more energetic than that; I was the one cleaning the acrylic as well as the windows and lights underneath the tunnel. That job usually gets my breathing up. My SAC rates were 0.653 and 0.686 cuft/min. When I get on that stationary bike or elliptical or treadmill, I can guarantee I'm breathing more than two thirds of a cubic foot of air per minute. I'm huffing!

How can this estimate be improved?