Yet Another Proper Weighting Question

[Straegen]

Take a SS back plate, add reg, all the hardware, and you already have 8 or 9 lbs...if one happens to be diving a steel tank, you now could be another 8 negative at the start...we are now up to 17 lbs... with only 13 left for lift...and nothing is ditchable. The wing would have to be pretty full, just to prevent it from sinking by itself.

This number assumes you are neutral with no additional weight. Most people in salt take a few pounds to sink naturally which is why these people should use a SS backplate. If you are neutral when you enter the water with nothing on, a very light backplate is probably the best solution. My understanding is, the backplate should offset as best it can your own personal buoyancy which doesn't change during a dive.

I think you will find just about every major mfg of wings makes their normal one around 40 (plus or minus a few pounds), and the light weight ones for tropical, light weight systems.

I think if you ask Tobin what he sells for singles, you will find not a lot of 40s go out the door. Most rec divers don't wear exposure suits nearing 30lbs of buoyancy.

Wet suit material vary in how heavy and how much it looses lift... I have 11 suits, made by 6 different mfg... the heaviest weighs in at over 20 lbs.. Many of the newer high stretch ones can go neutral to negative on a dive.

I think you plan for 0 buoyancy out of your wetsuit, but I would be impressed if a rec diver got a neoprene wetsuit negative.

It also means one is the most negative at the start.

I don't think this is always true. I know your tank weighs more in the beginning but in many cases diving in a wetsuit more than compensates for this at the surface. I think for wetsuit divers they are probably most negative at the first part of the dive at their deepest depth and most buoyant at the end of a dive.

Your comment about offsetting personal buoyancy would seem to have merit, but there a shops in the keys that rent LP steel tanks....and others that rent al 80's...as an example... weighted out for a AL 80 then, kind of sucks.

I would think a person would plan for steel tanks if they don't know. You can always add weight to a BPW to compensate for a lighter AL80. If your BPW with steel BP and tank far outweigh a divers natural buoyancy, that I would consider a bad idea. I would keep in mind that too much ditchable weight allows for the possibility of an uncontrolled ascent which can be bad as well.

 

[dpaustex]

I have to agree with the folks that say get in the water. You can calcualte all you want, but the in-water test is the BEST way.

Do the eye-ball level test (you should float at eyeball level with ALL of your gear on, and a full tank), with a lung full of air.

If you set your weights for that buoyance on the surface (empty BC of course), then you'll be pretty near perfect.

Remember, if you're overweighted, you're having to push that extra weigth through the water. The faster you burn calories, the quicker you draw down your tank.