weight loss and buoyancy adjustment

[mintaka]

Assuming if you dive keys you do not wear 7 mil suit and assuming regular tank was Al80 18 lb is way to much with your body composition if you ask me

I wear 5mil and 18lb with Al 80 would not allow me to submerge at the end of the dive (which was along a shallow shelf)--completely motionless--complete exhale--no air in BC. Dont know what else to say.

 

[mintaka]

Thanks for all the replies-- My original question was answered. I know that all new divers are overweighted. I didnt realize that one can determine how much weight a person needs just by knowing their height and weight ! I didnt even realize that I was overweighted with Al80 and 18lbs.

 

[mintaka]

I agree that it sounds like 18 lbs is quite a bit. It depends on the wetsuit you're wearing. Try tossing all the neoprene you're wearing and your BC in a mesh bag, in the pool or (even better) a calm spot in saltwater, and start adding lead to the bag until it sinks. If you have a 3 mil suit, which is pretty typical for the keys, it should be under 10 lbs to sink the bag. If it's more, take out the BC and try again. Some jacket BCs are surprisingly buoyant, which is yet another reason why I think they are the poster child for the dive gear industry gone wrong.

Anyhow, you can also put on a mask and snorkel, and check your own buoyancy in a bathing suit, you should be pretty close to neutral. Then add 4 lbs to sink the empty AL80, take away 2 lbs for your reg, add that to the weight to sink your wetsuit/BC, and that should be fairly close to your true weighting needs.

Then when all of this starts to get interesting and you still can't quite figure out why you're wearing so much lead to get down, try a steel backplate with a simple webbing harness (no padding!) and you can join the club of jacket BC haters.

Water temps the last two times I dove the Keys were about 70 F---My wife and I FROZE in 3mils which was the only size offered, so we bought 5mil (mine is a Henderson). Its really unfortunant that my first OW dive instructor said, "whatever you do, make sure to buy a jacket BC, not a back inflated !" I'm getting the idea that this wasn't the greatest advice. Based on his advice I did buy a jacket BC--I like you're advice about trying the steel backplate someday.

 

[elan]

Water temps the last two times I dove the Keys were about 70 F---My wife and I FROZE in 3mils which was the only size offered, so we bought 5mil (mine is a Henderson). Its really unfortunant that my first OW dive instructor said, "whatever you do, make sure to buy a jacket BC, not a back inflated !" I'm getting the idea that this wasn't the greatest advice. Based on his advice I did buy a jacket BC--I like you're advice about trying the steel backplate someday.

I think you got a good option - I was also diving keys in winter in 5 mil and it was comfortable 3 mill would probably be a bit cold for winter. I dont know if you have got the hood or not but if you have not I would recommend you one, it helps a lot

 

[halocline]

Wow 70F, that's definitely worthy of a 5 mil and a hood at lest. I didn't realize it was that cold down there.

And by the way, you can't determine how much weight someone needs by their weight/height, but you can get fairly close estimating, especially if you know their relative muscle/fat make up, and the buoyancy of the wetsuit. It's just that a male 5'9" and 155 lbs is probably pretty lean, and since I'm pretty close to that size and use 8lbs max (usually less) in a 3 mil suit, 18 lbs sounds like a lot. I also have a fairly buoyant 5 mil with hood, and with that I'm up to 10 lbs. Get the plate and see if your ever-so-helpful instructor can help you unload the jacket BC.