Weighting for Salt Water Dive

Question
I am a novice diver and am taking my first dive trip to key West in a few weeks.  What is the appropriate amount of weight for salt water diving?  I am 5'10 and weigh 180 lbs.  I will be wearing a 1 mm full wet suit, and will be diving with an Oceanic Cruz BCD as well as a 80 cf aluminum air tank.

Answer
Sure thing Michael.  Key West is some great diving and a good place to enhance your new skills.  Here is a guideline and a rough estimate for your weight.  Let the dive master of the boat know you may need to be doing a weight check and he can help give you more or less weights.

You should perform a 'weight check' prior to your first dive to determine if you are properly weighted.  To do this:  on the surface, without moving your arms and feet, take a breath of air and hold it with your reg in your mouth.  Let all the air out of your BC.  You should float just at eye level.  Then blow out the air you were holding in your lungs and that should be just enough to sink.  Kick back to the surface and inflate your BC and let the DM know you need 4 more pounds (to compensate for the buoyancy of an empty aluminum 80 tank).    If you don't sink after blowing out your breath, you don't have enough weight.  Being over weighted is not a good thing and should be avoided (if you start sinking after you deflate the BC but before blowing out a breath then you are overweighted).

Over time, as you dive more and achieve better buoyancy control you should find that you need less weight.  Best of luck to you sir, dive safely.

Example:  180 lb diver in a 1mm suit, in salt water, with an aluminum 80 tank would need:  
2 lbs (for 1mm suit) + 6 lbs salt water   + 4 lbs for AL 80 tank = 12 lbs

Do a weight check on the surface at the end of your dive also!!

You should be able to use way less than 12 lbs, probably about 8 depending on how comfortable you are in the water.



     Exposure Suit Type Weight
1) Swimsuit or skin, or 1mm  1 ?4 lbs
2) 3mm one piece or shorty 5% body weight
3) 5mm one or two piece 10% body weight
4) Add hood and boots 2 lbs
5) 7 mm two piece 10% +   4 ?5 lbs
6) Dry suit with light underwear 10% +   3 -5 lbs
7) Dry Suit with heavy underwear 10% +   7 ?14 lbs

     Body Weight Add from fresh to salt
1) 100 ?125 lbs 4 lbs
2) 126 ?155 lbs 5 lbs
3) 156 ?186 lbs 6 lbs
4) 187 ?217 lbs 7 lbs

     Tank Types (plan your weight for an empty tank)
Add or subtract weight according to empty buoyancy
  Type  Full  Empty
1) AL80 -1.4 lbs  4.4
2) AL100 -4.35  3.0
3) St HP80 -8.5 -2.5
4) St HP100 -8.5 -1.0
5) St HP120 -9.5 0