Sea Hunt Buoyancy Control Question

[jamiep3]

I learned to dive in the days of no BC, just a CO2 inflated vest for emergencies. I took a long break from the early 80's till 2002, when I recertified. In the new classes I took, I was loaded up with an amount of weight I couldn't believe, because I now had a BC.

What I learned is that Instuctors and Dive master now routinely overweight people on the theory that too much weight can be offset by the BC and this will help to prevent uncontrolled accents.

The bottom line is that in most cases, you lose 50% of your bouyancy at 33'. That said, with most exposure protection, if you are neutral with an AL80 on the surface, you willl still be negative at a 15' safety stop at the end of the dive.

Of course your mileage may very.

 

[Footslogger]

"Oldtimers" my butt! Weighting was more critical in those days when we either didn't have or couldn't afford BCD's. Much of buoyancy control was based on more precise weighting and use of our lungs (something a number of us still do). I don't remember it being that much of a challenge in the 60's and 70's. I didn't use my first BCD until 1989. Wouldn't dive without one now.

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Right On Dr Bill ...

I didn't own a BCD until the 80's myself. We wore simple backpacks with single/doubles and worked out our weights by trial and error ...oh yeah, and then there was breathing control. Funny how we didn't even give it all that much thought back then. Kind of a lost art in today's world of diving.

MJ

 

[Footslogger]

I've decided that I love this thread. It is SO relevant in this wild world of DIR and progress ...

MJ

 

[dumpsterDiver]

I learned to dive in 1973 and we didn't have pressure gages, or octopus on the regulators. The vests we used, had a tiny little hose to blow into while you pushed it down with your teeth. Basically snorkeling vests. Obvioulsy there was no power inflator or pull dump on the vest.

I remember that it was extremely hard to seal your lips around the hose to blow into the vest, if you had been down long in water that was below 45 degrees. My lips would be too numb to feel much and I think the muscles would be weakened by the cold.

It also was very hard to dump air from the little inflation valve when you had 7mm mittens on.
Within a year, I had purchased a pressure gage and also a next generation horsecollar BC which had an overpressure relief valve and a workable oral inflation method. I dove horse collar BC's exclusively until 1983, and still used them occasionally for a number of years.

I learned in cold water. Nobody did a feet first descent. You would actively swim down or use an anchor line to pull yourself to the wreck. We defintely adjusted our weight based on depth and you did not see people doing open water dives with way too much lead as you commonly see now.

I don't remember there being all the emphasis on neutral bouyancy. With a 1/4" or 3/8" (9mm) suit in cold water, you were pretty much going to be heavy below 60 feet. I used to pull myself along the wrecks and try not to kick up the bottom too much. We also learned to rest on silty quarry bottoms by very gently kneeling and then rising up out of it with a little hand swimming.

 

[Nemrod]

I also learned to dive before the BC was in use. It really is not diffucult but you have to make some concessions to the way things are done now. Your not going to have fun in a 7 MM farmer john, scooter or a drysuit, heavy multiple regulators and pony bottles and all of that junk---you going to have to be bare MINIMUM equipment. It just will not work with modern diver outfitted all sort of heavy gear to dump his BC but keep everything else--no way. You have to dump all the other junk to, maybe even the octapus and Spare Airs and etc. In moderate exposure suits (3/2) or a swimsuit and rashguard it is pretty simple. The lungs make a good BC. Your right, you begin the dive on the surface perhaps a little bouyant and you have to SWIM down until the suit compresses. You will then be somewhat negative but as the dive progresses and the tank is emptied you become more bouyant. By the end of the dive when we hit reserve we would be very light at depth. Remember that we did no do safety stops in this time so being bouyant allowed us to be comfortable on the surface but holding a safety stop midwater would be a challenge but as I said, we did not do that.

Even today, I try to get my weight such that I have little or no air in my wing through most of the dive, no more than a puff or two and I still use my lungs to tune my bouyancy. The best place to learn this is in a pool in a swimsuit, steel 72 tank. Oh, the aluminum 80 actually works well, not as good as the 72 but it will work. Heavy steel tanks, the kind that start out 10 or so pounds negative will not do but maybe with heavy exposure gear and then your going to have a huge swing with that heavy compressible suit. You need a tank that hangs around neutral, maybe slightly positve at the end. Even among the vintage crowd we have slightly different methods, since I am not a cold water diver I have never tried no-BC diving in anything more than a 5 MM full suit or a 7MM top (without pants) as we used to dive. I find a 3/2 pretty easy to dive, beyond that it becomes a bit more challenging, especially with some modern neoprenes. It is generally not considered terribly bad form to grab a stone to act as ballast--lol.

I realize that divers today like negative tanks because they use the BC to compensate and this allows weight to be removed from the belt, for vintage that is wrong, the wrong approach. You need a tank that stays close to neutral. The alumium 80 is about 2 pounds neg full and about 4 positive empty. At mid dive it is neutral--NEUTRAL. That means a guy in a swimsuit and rashguard or even a 3/2 will only need the weight on the belt to compensate the suit. A steel 72 will be a bit more negative an beause it is smaller in displacement a bit less swing. You must be able to ditch the weight in case you have a problem on the surface and need to be bouyant. Non ditchable negative tanks and plates will not allow you to be bouyant at the end of the dive and you will bottom bump through the whole dive. It is like being on a teeter board, you want to be neutral so any weight more than needed is bad. N

 

[Gary D.]

I started in 62 and back then there was no such thing as being gear dependant as it is today.

Double hose regs changed breathing resistance by just by how you were positioned in the water column. Weighting took more planning than the dive itself, masks looked like a Dixie Cup with a clear bottom, everything was black, fins were either floppy or like boards and suits were fairly stiff. Tanks could have been steel, aluminum designed for scuba or a fire extinguisher acquired from some commercial business. Computers were something out of a Flash Gordon science fiction movie, The BC hadn’t been invented yet and Suit zippers were salvaged from Blue Jeans. Mittens were much more comfortable and warmer than gloves, hoods were thick enough to be used as “C” Collars in an ambulance and very little was made out of plastic. A big percentage of gear like cameras, spear guns, weights, watches and other accessories were DIY.

About the only relationship between the 60’s and now is that they both are in the water. For those that complain about today’s diving need to suit up like 45 years ago. It may give you a better appreciation for what you have and how easy it is today. Today very few fail OW. Back then very few passed it.

AND, it was expensive, much more so than today. I had a Gun Metal Gold 62 Ford Crown Vic, 406 with 3 deuces, 4 speed, positraction, real Mag wheels and racing suspension. When it was empty I could fill it Ethyl for under $5.00 which was expensive back then. But it got to dive sites mighty fast. Job? I got $1.00 an hour and $.10 a mile to deliver Heavenly Fried Chicken and Ribs.

Gary D.

 

[fisheater]

I am really enjoying the lessons here. Thanks folks.

 

[miketsp]

My Spirotechnique wetsuit from 1971, which I still have although the original zipper corroded to dust about 10 years ago and had to be replaced, is made of much denser neoprene than the suits today so the buoyancy change with depth is significantly less.

 

[james croft]

And I had to walk ten miles through the snow everyday just to get to the quarry. You kids don't know how good you have it...

 

[captain]

I started in 62 and back then there was no such thing as being gear dependant as it is today.

Double hose regs changed breathing resistance by just by how you were positioned in the water column. Weighting took more planning than the dive itself, masks looked like a Dixie Cup with a clear bottom, everything was black, fins were either floppy or like boards and suits were fairly stiff. Tanks could have been steel, aluminum designed for scuba or a fire extinguisher acquired from some commercial business. Computers were something out of a Flash Gordon science fiction movie, The BC hadn’t been invented yet and Suit zippers were salvaged from Blue Jeans. Mittens were much more comfortable and warmer than gloves, hoods were thick enough to be used as “C” Collars in an ambulance and very little was made out of plastic. A big percentage of gear like cameras, spear guns, weights, watches and other accessories were DIY.

About the only relationship between the 60’s and now is that they both are in the water. For those that complain about today’s diving need to suit up like 45 years ago. It may give you a better appreciation for what you have and how easy it is today. Today very few fail OW. Back then very few passed it.

AND, it was expensive, much more so than today. I had a Gun Metal Gold 62 Ford Crown Vic, 406 with 3 deuces, 4 speed, positraction, real Mag wheels and racing suspension. When it was empty I could fill it Ethyl for under $5.00 which was expensive back then. But it got to dive sites mighty fast. Job? I got $1.00 an hour and $.10 a mile to deliver Heavenly Fried Chicken and Ribs.

Gary D.

I had a 1963-1/2 Galaxie fastback, 427, dual four barrels, four speed, I miss that car, of the many cars I have owned, it's the only one I wish I still had.