Basic weight question

[PaulVS]

I'm sure this has been discussed previously - but searching through dozens of posts about weights is a little too much.

Basically, I need to know how much weight my wife and I should put in our new weight-integrated BCD's. I'd like to buy the weights now so we are ready to go when we dive in Cancun & Cozumel this coming June since that is the first time we'll have an opportunity to do a salt-water dive with our own equipment. (I just bought us all of our scuba gear from ScubaToys.) Previously in our ocean dives we've rented equipment and just relied on the DM to assign us weights.

I would think a little too much weight is better than not enough weight in salt water since you can always compensate with BCD inflation... which is better than trying to 'force' yourself underwater. Correct me if I'm wrong on that one.

I'm 6'2", 235lbs and she is 5'8" 133lbs.

Any advice on the amount of weights we should start with as well as the type of weights for a weight-integrated BCD is appreciated. (I know a lot of it depends on body fat % etc.)

 

[H2Andy]

paul, for a new diver, it is "easier" to be over-weighted, but not necessarily "better."

it's a very good idea to shoot to be neutral or 1 or 2 lbs over, at the most.

there is no substitute for actually trying out how much weight you actually need.

you will need to try this:

-- get a tank with 500 psi or so in it

-- get down to about 15 feet

-- see how much weight you need to stay in control (i.e. not "pop up" out of control)

-- make sure your BC is empty and you are breathing normally (don't hold your
breath or empty your lungs)

you can take weights down with you and put them on the bottom, then
hold them and/or drop them as needed.


you want to be able to control your bouyancy with an almost empty tank
during the last 15 feet of ascent. you don't want to lose control of your bouyancy
at this point and pop to the surface. you want to be able to ascend and
descend at will.

now, if you can descend here, with an almost-empty tank, you will certianly
be able to descend at the beginning of a dive with a full tank.

things to do to make sure you can descend with the correct weight:

-- empty your bc all the way

-- stop kicking

-- try not to fill your lungs with air. breathe shallow.

-- wait

-- wait

you will start to sink =)

 

[PaulVS]

-- get a tank with 500 psi or so in it

-- get down to about 15 feet

-- see how much weight you need to stay in control (i.e. not "pop up" out of control)

-- make sure your BC is empty and you are breathing normally (don't hold your
breath or empty your lungs)

you can take weights down with you and put them on the bottom, then
hold them and/or drop them as needed.

I can do that... but only in a freshwater pool until we are actually in Mexico. The problem is that my bouyancy in fresh water is quite low, but while snorkeling in seawater I can't get much more than 5' deep without a lot of effort.

I think we need a liberal ballpark saltwater weight recommendation - we can always off-load weights based on our first dive in saltwater - and I'm sure you would agree that even if we were both as much as 10lbs overweighted we could either:

1) Compensate with BC inflation.
or
2) Dump the weights.

 

[hdtran]

I'm sure this has been discussed previously - but searching through dozens of posts about weights is a little too much.

Basically, I need to know how much weight my wife and I should put in our new weight-integrated BCD's. I'd like to buy the weights now so we are ready to go when we dive in Cancun & Cozumel this coming June since that is the first time we'll have an opportunity to do a salt-water dive with our own equipment. (I just bought us all of our scuba gear from ScubaToys.) Previously in our ocean dives we've rented equipment and just relied on the DM to assign us weights.

I would think a little too much weight is better than not enough weight in salt water since you can always compensate with BCD inflation... which is better than trying to 'force' yourself underwater. Correct me if I'm wrong on that one.

I'm 6'2", 235lbs and she is 5'8" 133lbs.

Any advice on the amount of weights we should start with as well as the type of weights for a weight-integrated BCD is appreciated. (I know a lot of it depends on body fat % etc.)

In addition to the body fat (actually, that's not a huge component), there's the exposure suit (or lack thereof), the air volume trapped in the mask, and, as Andy said, being relaxed, having the inside of your wetsuit filled with water, etc.

Did you happen to log how much weight your DM's assigned you in the past?

Also, how easy is it to load hard weights into your weight-integrated BCD's? You might just rent the weights (usually included with the tanks), and avoid packing lead

p.s. edit-added: Just saw your response to Andy. If you know your needed freshwater weighting, your total buoyancy is approximately 3% greater in saltwater. So, if you weigh 80 lb & need 20 lb of weights to be neutral in freshwater, you'll need approx 23 lb of weights for saltwater. The math works out like this: Total volume displaced for neutral is 100 lb freshwater. Therefore, for saltwater, need to displace 103 lb (I think the actual specific gravity is 1.025, rather than 1.03, so if you want to quibble a decimal point, 102.5 lb). Since your weight remains the same (80 lb), you need to wear 23 lb to get a total weight of 103 lb. There's a minor correction needed for the volume of water displaced by lead weights, but that's really minor...

 

[H2Andy]

I can do that... but only in a freshwater pool

no problem!

if you know the amount of weight you need in fresh water, you multiply the weight of the diver (together with gear) by .025 and that gives you the additional weight that will be necessary in salt water.

so, say you need 10 lbs in fresh water to stay neutral/slightly negative at
15 feet... ok...

now, kit up, and weigh youself. say, you weight 200 lbs...
well... .025 x 200 = 5lbs, so you will need 15lbs in salt water.

one thing i can't remember now (since i've never done this) is whether you wear
your weights when you weight yourself

i dont' think so... but... anyone remember?

 

[hdtran]

no problem!

if you know the amount of weight you need in fresh water, you multiply the weight of the diver (together with gear) by .025 and that gives you the additional weight that will be necessary in salt water.

so, say you need 10 lbs in fresh water to stay neutral/slightly negative at
15 feet... ok...

now, kit up, and weigh youself. say, you weight 200 lbs...
well... .025 x 200 = 5lbs, so you will need 15lbs in salt water.

one thing i can't remember now (since i've never done this) is whether you wear
your weights when you weight yourself

i dont' think so... but... anyone remember?

Andy, yes, you need to weigh yourself + all equipment. This is the total weight you have that leaves you neutral in freshwater (e.g. all the volume you displace). You then multiply by 1.025 (more like 1.027 or 1.028 in the Red Sea, if I recall correctly ), and that's your total saltwater neutral weight. We assume lead is incompressible, etc.

Hy

 

[carldarl]

H2Andy has given good advice. Here is a little information that may help ballpark it.

I am 6'3" and weigh 265 pounds. With a 3/2mm full wetsuit and booties I use 24 pounds of weight. I am "slightly" heavey with that but my camera housing is slightly positive so it works. I originally had 32 pounds on my first sw dive. "I've lost weight" )

My wife is 5'6" and weighs about 145???. I have no idea what she uses as she says that is one more thing you never ask a lady!

There is no need to buy, pack and carry your own weights if you are diving with a commercial operation. They will supply you with tank and weights. The only thing you may want to do is pack a couple 2 pound soft weights each to fine tune. The operators usually only seem to have 4 or 5 pound solid weights.

Also, on day one or the first dive tell the DM you get that you have never dived sea water before and can you take time to do a weight check to get it right? They will usually say absolutely.

Relax and enjoy a whole new experience. If like us it will have you looking for vacation/retirement property in Belize.

 

[PaulVS]

Thanks for all the info!

Based on everything - I'm going to try it out at the pool, although it is only 9' deep.

Sounds like if I start with 20lbs I should be okay - but I'll try to fine-tune it more in the pool with my waterproof calculator. ;-)

 

[DiveMaven]

I have to agree with Carldarl, you don't need to buy and take weights to Mexico. On boat dives, they will be included with the charter price, and if you're going to shore dive, it's easy to rent weights for a few bucks when you get your tanks.

 

[DanBMW]

You really don't need to take any lead with you on a trip to Cozumel. Most commercial boats will have all the lead you can use. Definitely work on your buoyancy and follow the above posters advise. If there is a class you can take on buoyancy, it will be worth it. You will notice as you get more comfortable, you will shed lead. This is normal and by the end of your trip you might be able to be diving with 2/3's of what you started. Have fun, the visibility in Cozumel is excellent.