Figuring weights for freshwater?

[slackercruster]

My wife is about 245 pounds and is using a 3 mm full wetsuit without hood. She is using a regular BC and 80 CF alum tank. For diving in freshwater how much weight should she try on for the first dive?

Thanks

 

[diver 85]

Very vague question but here goes---I use 12# in freshwater in a 3mm & 80 Al tank---I'm of the other sex and about 205#.....start with ?20 lbs??...BUT, there are alot of variables out there to change this a few pounds(higher I would guess)...

 

[redacted]

I'd allow 8 lb for her wet suit and no more than 8 lb for her and the rest of her gear. I would also expect that 16 lb total will drop another 2, 4, or even 6 lb as she gains experience. If you will be with her, I'd suggest 12 lb on her belt and 2 lb in each of her pockets. Just to be absolutely safe, you might want to throw a couple 2 pounders in your pockets as many new divers are hesitant to exhale enough to initially submerge.

 

[The_DivePirate]

Standard guidlines would be, 5% of her body weight in saltwater - 7-8 lbs. for the freshwater + 5lbs. for the al 80. for a total of 10.25 lbs. But, my guess would be somewhere around 15-20 lbs. depending on her comfort in the water. But in the end she should be somewher around 10-12 lbs.

Goodluck,
Joe

 

[cudachaser]

Here's the way I look at the problem:

Fresh water weighs 62.4 #/ft
Sea Water weighs 64.0 #/ft

That's a 1.6 # difference for 1ft3

An average person say 5'6" and 160lbs displaces about 2 cubic ft of water...that equates to 3.2 lbs extra going from fresh to salt--for the sake of simplicity, call it 4 additional pounds since weights generally don't come in decimal increments

From your wife's apparent size I would go with 3 cubic ft X 1.6lbs or 5.2lbs rounded up to 6 #

 

[calvin007]

Another easy way is to do a buoyancy check, either with a full tank or empty tank (preferable). With a full tank, once you figure out how much is necessary to hold you at eye level with half to full breath in your lungs and no air in your BC, add another 5 lbs for an Al-80. With an empty tank (nearing 500 psi), just add enough weight for her to be able to submerge below the water line with the BC fully deflated. I always do this when I have a different gear configuration or am traveling to make sure I am not carrying more weight than what I require, which can be a real 'drag' underwater. It's a quick and easy test.

 

[The_DivePirate]

Here's the way I look at the problem:

Fresh water weighs 62.4 #/ft
Sea Water weighs 64.0 #/ft

That's a 1.6 # difference for 1ft3

An average person say 5'6" and 160lbs displaces about 2 cubic ft of water...that equates to 3.2 lbs extra going from fresh to salt--for the sake of simplicity, call it 4 additional pounds since weights generally don't come in decimal increments

From your wife's apparent size I would go with 3 cubic ft X 1.6lbs or 5.2lbs rounded up to 6 #

This would probably work, that is if she can hold her breath for an hour.
With an al80 the buoyancy characteristic's would create an issue at her safety stop. In a perfect world, 9.25 lbs should do the trick. So again, IMO 15lbs. would be a good starting point.
Joe

 

[dumpsterDiver]

Here's the way I look at the problem:

Fresh water weighs 62.4 #/ft
Sea Water weighs 64.0 #/ft

That's a 1.6 # difference for 1ft3

An average person say 5'6" and 160lbs displaces about 2 cubic ft of water...that equates to 3.2 lbs extra going from fresh to salt--for the sake of simplicity, call it 4 additional pounds since weights generally don't come in decimal increments

From your wife's apparent size I would go with 3 cubic ft X 1.6lbs or 5.2lbs rounded up to 6 #

You also have to consider the wight of the divers gear, including the tank, weight belt etc, when calculating the difference. Another maybe simpler way is to multiply the total diver's weight and gear by 2.5% to get the extra weight needed. So the diver and gear weigh around 300 plus, the extra weight is closer to 8 lbs.

 

[String]

Dont really see the point of these questions - a proper weight check takes 2 minutes and is guaranteed to get it done correctly.

 

[Walter]

Dont really see the point of these questions - a proper weight check takes 2 minutes and is guaranteed to get it done correctly.

Exactly, but IF the diver has already done a proper weight check in salt water and IF the diver will be wearing EXACTLY the same gear in fresh water, multiplying the total dry weight of diver and gear by .024 will also be guaranteed to give the correct result.