Originally posted by ms tomato
My husband quite smoking 3 months before our trip to Cayman (good for him) but he had so much trouble with his buoyancy that we were only able to do 2 dives on different days and they were very short. I have a feeling his is breathing so heavily from the exertion that he just can't stay down. He just floats to the top. He had probably 30 lbs on his weight belt and that didn't help. Will this problem go away when his lungs begin to heal? I was disappointed for him and for myself also. We did A LOT of snorkeling and it was all beautiful. Other than that we had a great trip and Cayman was wonderful. Ms Tomato
You don't mention how much exposure protection your husband had on but in the tropics it was probably light. Given this, 30 lbs on the belt is
way, way too much weight unless he is very fat. If 30 lbs is correct I suspect that your problem may have been this weight belt as I describe below.
If you put far too much weight on the belt you become significantly negatively buoyant. You therefore must add a lot of air to your BC to compensate. But, that amount of air will be correct for only one depth. Remember that as you go up or down the air in the BC will expand or compress and your buoyancy will change.
With too much weight on the belt you also have to have way too much air in the BC (or more accurately far more air than you would need if you were properly weighted). This large air volume makes for larger buoyancy swings as you go up and down in the water column during your dive and requires you to add or remove larger amounts of air to adjust buoyancy. (If you dive from surface down to 60 ft. the volume of air in your BC will reduce by 66%. If you need to have a lot of air in your BC at surface then at 60 ft the amount of water displaced by you and your gear will be significantly less. If you have little or no air in your BC at surface then 66% of nothing is nothing and your displaced volume changes little at 60 ft, mostly just whatever compression of your wetsuit occurs. Therefore your buoyancy changes little.) The addition and removal of large amounts of air to adjust buoyancy takes time and is difficult to get right. You can get into an adjustment feed back loop where you are constantly adding and taking out air, over and under correcting, never getting it right and never having the right buoyancy. If you come up from any significant depth you can also get into a runaway ascent if you aren't dumping enough air.
Over weighting instead of correct or under weighting can sometimes feel like a comfort to new divers but significant overweighting can be dangerous. If you have a BC bladder failure and are diving wet you will have to swim that weight up from depth.
Next time I think that you should get some advice about proper weighting and dive with much less lead. Keep a written record of how much weight you need with different gear setups (I assume you are renting on these travel dives?). I keep this record in my dive log. You can try practice in a pool but diving in salt water will require a bit more weight.
All of this assumes you were correct on your guess of how much weight he had on. Oddly enough being overweighted or underweighted can both cause positive buoyancy problems. A Luxfer Al 80 tank weighs 5.8 lbs more full than empty. During the course of your dive you can easily loose up to 5 lbs of weight. This can cause you to become buoyant late in the dive if you don't have enough weight. Either way you probably need to practice your skills and pay attention to weighting.
