Proper Weighting

[H2Andy]

me:

5'10
175 lbs

fresh water:
3mm farmer john; 3 mil vest with hood (i.e. 9 mil on chest)
BP/Wings
5-lb light canister
95 Steel tank
No weight needed

salt water:
3mm farmer john (i.e. 6 mil on chest)
BP/Wings
80 Aluminum tank
10 lbs needed

 

[ShakaZulu]

Me

5,11 ft
185 lbs

salt water:
7mm full suit (new)
Back Inflate BC (Seaquest Black Diamond M)
80 Aluminum tank
24 lbs needed (thus 10% would be 18.5 + 5.5 = 24)

And I still have problems staying at 10ft with tank at 500psi (too positive).

 

[Willar]

I was thinking the 10% + 5-7 sounded crazy, but I understand the wetsuit makes a difference. I only dive warm water in a 3mil or 1.5mil and require 12lbs in saltwater. I am 6'0" and 210lbs so the rule of thumb would have me wearing 26 lbs. The most I've ever worn is 15 and I felt like a big ole' rock.

Be sure to check bouyancy with an EMPTY tank, especially when using an aluminum tank. AL tanks will be positively bouyant when empty and can make that 15' stop very tough if underweighted.

 

[headhunter]

I had a related question a couple of days ago about why some people recommend the eye level at surface method and others recommend the neutral at 10' safety stop with empty BC and 500 psi method. I posted it in the DIR forum because I wanted to know what the official DIR answer would be. MHK was kind enough to answer the question and then clear up some of my confusion. The discussion may prove helpful you, so here is the link:

http://www.scubaboard.com/t61480.html

Christian

 

[TCDiver1]

Well, a "rule of thumb" is meant to be just that, it isn't intended to be exact. Its a place to start if your not sure or until you can calculate a better answer. What we use for weighting rule of thumb in these cases, based on Alum. 80's & fresh water:

- Shell Dry suit & cold water underwear
(Neo. suits can require more)
10% + 8lbs

-Full 7-8mm wetsuit
10% + 6lbs

-Full 3mm wetsuit
5% + 3lbs

We have found these to be good starting points for divers who don't already know about how much they need. Some need more, some need less.

Almost every diver drops weight as they become more experienced and comfortable in the water.

 

[aviddiver(him)]

FULL vs empty tank when determining weithing?

Seen this discussion before.

Perhaps it's time to revisit?

Best advise for new vs seasoned diver; alum vs steel; neutral at SS vs surface; warm water vs cold water; wet/dry suit vs skin; what's going to get you to surface in OOA situation, etc. etc. etc.

IMHO - testing weighting with FULL tank is best.

Lively debate anyone?

 

[donacheson]

FULL vs empty tank when determining weithing?

Seen this discussion before.

Perhaps it's time to revisit?

Best advise for new vs seasoned diver; alum vs steel; neutral at SS vs surface; warm water vs cold water; wet/dry suit vs skin; what's going to get you to surface in OOA situation, etc. etc. etc.

IMHO - testing weighting with FULL tank is best.

Lively debate anyone?

It's OK to weight yourself by getting neutral with all your gear and breathing normally just below the surface with an empty BC and full tank IF you add 5 or 6 pounds of lead for each tank on your back before you dive.

 

[String]

So many factors such as suit type, (wet, dry, neo, membrane, undergarments), tank type (steel, aluminium), tank size and max pressure rating, water salinity, body fat/muscle/bone density, lung capacity and so on no formula is accurate at all.

The way we're taught is to be able to hold a 6m stop (slightly negative there) with a near empty BC with a near empty tank.

Me personally.

5ft 9"
170lbs

Membrane drysuit + weezle + steel tanks (12l and 15l 300 bar) i need 11kg (24lbs)

Abroad in 28c water, 5mm full suit, steel 12l tanks i need just under 3kg (6lb).

Both those salt water as ive never dived fresh.

FWIW to be able to stay on the bottom in the pool with no suit but same tank i need about 1.5kg.

A persons weighting will depend even on what they ate recently and physical condition, most people have to do a weight check at the start of a new season here and find its changed.

---

Full/empty tank debate - empty tank every time for me. You need to be able to stay down assuming a worst case scenario - OOA or very near. Although you can calculate the "weight" of air in a full tank and calculate backwards to work it out its more accurate measuring on empty.

Every diver will start every dive 3-4kg overweighted purely due to the air in their tank (more if on twinset etc).

One fairly useful url for working out the weighting changers of different cylinders is here:

http://www.subaqua.co.uk/cgi-bin/cylinder-buoyancy.cgi

 

[O2BBubbleFree]

I typed up some guidelines that I was given by my LDS and posted them on the above-mentioned thread.

http://www.scubaboard.com/t61010.html

These are fine for a starting point. Work for me as well as others that have used 'em. Of course, this just gives a rough starting point and must be fine tuned for different dive conditions (salinity, altitude, etc..)

 

[aviddiver(him)]

I'm overweight and negative, but maybe I'm just too dense to understand Archimedes law

"... too dense to understand ... [negatively buoyant, overweight, Archimedes 'weight of H2O displaced = neutrality']

REALLY like your signature, 3dent !