Body weight to weight ratio?

[D Powell]

Is there a rough guide ie 147lbs = x amount on weight belt.

If so is there a formula for fresh compared to salt water?

 

[Walter]

Nothing that works.

For fresh to salt, multiply the dry weight of yourself and all your gear (including lead) by .024. Add that amount of lead.

 

[JacobK]

There are a lot of factors involved in determining how much weight you need on a weight belt. I do have a web page print out that can help you to get a rough guess on how much weight you will need, but it is in my dive book. I have to look it up and post it here. (I think I may have found it on this board to begin with.)

For the formula... it is 40 lbs of total weight to 1 lb of weight on the belt. So, if in fresh water you are neturally buoyant and your total weight is 160 lbs (total weight being you and all of your gear on), you will need to add 4 lbs onto the weight belt when you go into salt water. This will get you close.

Do the reserve (remove weight) if you move from salt to fresh.

 

[Calinectes]

There's no real formula for figuring out weights. It has more to do with body composition than anything else. Fat floats, muscle which is 3X denser sinks. Always do a buoyancy check in the pool with all the gear you will use on your dive. You can add aproximately 6 lbs. (~3 Kilos?) for salt water given everything else is equal.

An aside: beginning divers tend to need a little more weight at first to compensate for inexperience (I'm not kidding). As you become more comfortable with everything miraculously weight will come off the belt.

 

[JacobK]

An aside: beginning divers tend to need a little more weight at first to compensate for inexperience (I'm not kidding). As you become more comfortable with everything miraculously weight will come off the belt.

Agree.. on my first OW dive, with a 7 mil wetsuit and a steel 72, I had 28 lbs of lead. Even with 28 lbs, it was struggle to get down.

On my last dive (career dive number 13), with the same setup, I was at 26 lbs. At 26 lbs, I did not have any problems descending and was able to maintain netural buoyancy at the safety stop.

Next dive.. I will try 24 lbs.

The key is to just relax and breathe shallow when descending.

 

[terrasmak]

Tank, wetsuit , body fat, BC or back plate , way to many factors . Best bet is your instructor or LDS should be able to help you out with that part of your set up then you have to fine tune it yourself.

 

[pasley]

Factors to consiter and variables.
1. Fat to muscle ratio as has been said, fat float, muscle sinks
2. Wetsuit density and coverage. A 145 pound 6ft. tall diver in Hawaii may wear only a swimsuit, while the same diver in Los Angeles, CA is sporting a 7mm full wetsuit, hood and vest or a dry suit. Each will have their own weighting requirements.
3. Type of tank, AL or steel small or large
4. Jacket BC, Back inflate BC or backplate?

This chart should get you in the right ball park, but is not perfect:
http://dive.scubadiving.com/html/200105buoyancycalc_chart.html

 

[DandyDon]

There are formulas, but none work. :11:

 

[MSilvia]

Is there a rough guide ie 147lbs = x amount on weight belt?

No. As others have said, there are other variables that need to be considered. For instance, a 147lb person in a 3mm shorty with a steel tank will need to carry much less weight than a person in a 7mm 2-piece full body wetsuit with an aluminium tank.

Your best bet is to make a guess, and then adjust until you get it right. Spending a dive getting your weight "dialed in" is well worth it.

If so is there a formula for fresh compared to salt water?

Yes, but it's usually easier to guess, as in most cases it's a matter of a few pounds. If you usually dive in salt, try taking a 5lb weight off in fresh water and you'll probably be close.

 

[JacobK]

This chart should get you in the right ball park, but is not perfect:
http://dive.scubadiving.com/html/200105buoyancycalc_chart.html

That is the chart I mentioned in my earlier post. I have never used it since all my diving has been with the same equipment since dive number 1.

Thanks Melvin... Saved me a trip to my "dusty" dive log.