How much weight?

[oldenred]

I am 6' 275lbs, chunky but carry my weight well , lol. I will be diving with a steel 120 weighs 39lbs. I will also have a alum 30 for emergency air. Wetsuit will either be a 3 mm or a 6mm and it will be in saltwater in 60-120'. Where should I start around. I was thinking about 16lbs. Correct me if i'm wrong. Thanks

 

[mk706]

Tobin and Andy have addressed this very topic in numerous posts, here is one: http://www.scubaboard.com/forums/ad...weight-lift-capacity-gear-buoyancy-tobin.html


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[tbone1004]

oh that is all but impossible to determine based on the information you gave. You 100% have to hop in the pool and figure it out. That is, exhale completely and you sink, but on a normal breath of air you barely float at the surface. You have to do this with each wetsuit because not all 3mm's and not all 6mm's *which I don't know exist.... I think they're usually 6.5mm farmer johns* are created equal, so not possible to determine that. The aluminum 30 should not be factored into weight discussions, but empty they are +1.2lbs without a valve, so with valve and regulator they will still sink, even when empty.

You didn't say what type of 120 you actually have but based off of weight, it is likely a PST HP120, which is -1.3lbs when empty without a valve, so that comes in around 3lbs negative with a few CF of air left, the valve, and regulator.

You didn't mention what type of BC you're using. If you're using a SS backplate, with a SS STA, and SS cambands, that is 10lbs negative right there, if you're using a stab jacket, some of those are a couple pounds positive because of the padding. You need to figure out what that is. The only way to properly do weight checks is in the pool with equipment on. You will likely also breath too heavy and like 99% of the divers out there require at minimum 2lbs more lead than you need to actually be neutral.

Doesn't matter how well you "carry" your weight, fat is fat, and muscle is muscle, doesn't matter how it is dispersed. I'm 6'4" 280, but I still sink like a brick because it is almost all muscle, you likely will not sink, very few people naturally sink. That's ok, but that's why you need to figure that out in a pool. Have a 2x1lb weights, 2x2lb weights and 2x5lb weights at bare minimum, an empty weight belt, and a buddy. You get in the deep section of a pool *has to be over your head, so 8' deep minimum* and hold onto the buckle end of the weight belt. Your buddy holds the other end. With just you, no exposure suit, exhale all the way and see if you sink. If you do, great, don't be surprised if you don't. If you don't, put a 2lb weight on, and repeat. Go up in 1lb increments until when you exhale all the way, your head goes under water and stays there for a couple of seconds. When that happens, your buddy should pull you back up. Write down that number, that is how much ballast you need individually to sink.

Repeat this exercise with each of your exposure suits, including gloves, boots, hood. This will take at least 1 hour and since you'll be wet, you need to get the wetsuit wet to put it on. The other way to do this is to put the wetsuit into a mesh bag with handles, and put lead on top of the suit until it starts to sink. Probably faster and fairly accurate, but you still have to do what's mentioned below with just you and make sure that hoods, gloves, boots are in the bag with it.

These are very very important numbers to know that the vast majority of divers *including dive professionals* have no idea about. This allows you to dive with any gear and know exactly how much weight you need for that exposure protection level and dive gear. Say it takes you 16lbs to get neutral with just that wetsuit, you then buy a SS bp/w setup, you know that automatically that now drops to 6lbs, you're diving an AL80 because you had to rent a tank, have to add 4lbs to that to counter the tanks buoyancy. Diving that steel 120, you can take 2 or 3 lbs off of that because of the tank. Much better situation to be in.

good luck

 

[flots am]

I am 6' 275lbs, chunky but carry my weight well , lol. I will be diving with a steel 120 weighs 39lbs. I will also have a alum 30 for emergency air. Wetsuit will either be a 3 mm or a 6mm and it will be in saltwater in 60-120'. Where should I start around. I was thinking about 16lbs. Correct me if i'm wrong. Thanks

Get in the water with your desired equipment, no weight, an empty BC, a mostly empty tank, a buddy and a bunch of small/medium weights.

Have your buddy hand you weights until you're at about eye-level with mostly exhaled lungs. This should be very close to what you need, although you might need to add a couple of pounds depending on how anxious you are underwater and how your trim is.

Anything else is just a guess.

flots.

 

[DivemasterDennis]

Weight check, weight check, weight check. The two different possibilities for exposure suits will impact proper weighting, as will equipment type and materials, as stated above. Fresh vs salt water will also have an impact of a few pounds. So will your body mass and type of mass (lean muscle vs. alternative weight. Do not short cut this process. Overweighting will negatively affect your buoyancy control, increase air consumption, and otherwise be a bad thing. Underweighting can be hazardous in not permitting proper safety stops and buoyancy control. There is no substitute for a proper weight check. There is no calculus for weight without a weight check.
DivemasterDennis

 

[kensuf]

Trying to "guesstimate" based on rough numbers can be wildly off due to body composition, and other factors. Simply said, a 250# body builder that has 6% body fat is going to be a lot more negatively buoyant than someone that is, uhh trying to be PC and sensitive here, a little fluffy.

When determining your buoyancy you should strive for being able to be neutral with almost no air in your BC, 500 psi in your tanks, and in 10'-15' of water. The best way to figure the exact weighting out is as others have said, weight check and adjust as necessary.

Adjustment to/from salt water involves adding/subtracting weight. 2.5% per 100lbs is a pretty good guesstimate, at least good enough for government work. So if you did your weight check in fresh water, and you're diving off a boat, and your total body and gear weighs around 200#, add about 5 pounds to your setup.

If you change things like wetsuits / drysuits, you'll need to re-adjust as well.

Best of luck,

Ken

 

[drbill]

As has been pointed out, a weight check is the best way to determine what YOU need. Out here in Socal our basic rule-of-thumb for a diver in a 7mm wetsuit with a single tank is 10% of body weight plus 5-7 lbs. I dive with a massive 38# of weight (as a videographer I do overweight myself to remain stable) using a neutral buoyancy Al80 and a 30 cu ft pony. I weigh about 250 (and carry it... "well").

 

[tbone1004]

Bill, you know as well as anyone that those numbers are dangerous to follow and . For my that would be 35lbs of ballast. In a 5mm with a single 72 I'm sinking in a transpac. That is the way most agencies teach and unfortunately that exacerbates the problem of being overweight in the industry and then people assume that follows the whole way thru and it never gets fixed

 

[Roman_66]

Fresh vs salt water will also have an impact of a few pounds.

I 5'11 / 260 (too much fat, I know...). In fresh water 1 mm long suite + Halcyon back plate (6lb) + adapter (1lb) with regular LAL80 I don't need any more weights.
The same configuration in salt water I need to add 8 lb.
Did weight check again in fresh water with dry suite with DryBase and Xerotherm underwear (instead of 1mm long suite ). Need 12 and 16 lb accordingly. All other equipment the same.
Now I booked Flower Garden Labor day 3 days trip, I don't have option to check weight in salt water before trip (more than 5 hours driving from Dallas) with my new configuration.
Need to guess : or just add 8 lb or calculate proportionally:
Configuration 1 : Fresh water 7 lb :-: Salt water 7 + 8 = 15 lb
Configuration 2 : Fresh water 7+12 = 19 lb :-: Salt water 7 + X lb
Configuration 3 : Fresh water 7+16 = 23 lb :-: Salt water 7 + Y lb
7 + X = (19 x 15 / 7) = 41
X = 41 - 7 = 34 lb
7 + Y = (23 x 15 / 7) = 49
Y = 49 - 7 = 42 lb
Once I did check weights in salt water in dry suite (Base underwear), it was Red see, but with AL80 doubles. I was need 30 lb. Also Red see much more salt than Caribbean.
Second AL80 gives about +3.4 lb positive buoyancy then empty, but second valve, manifold and bands I think about 2-3 lb negative. I also don't have adapter 1lb than dive doubles.
So looks 30 - 2 (transfer from double to single) - 2 (more salt Red see) = 26 lb will be needed in Flower Garden trip.
It bring me to third number
1. 12 plus just 8 = 20 lb 2. proportional calculation =34 lb 3. Red see double based calculation = 26 lb
Not sure that after first dive in Flower Garden I will have option to check my weights as I heard all activities happened very fast.
I also bought Sherwood HP120, which is -4.6 negative when empty, but here calculation should be simple. LAL80 +3.4 , so I will reduce about 8 lb from all calculation above.
Suggestions? Corrections ? Comments ?

 

[lemke]

I'm 6-2/220... with a 3mm full suit, SS bp/wing, and a hp119 or lp108, I need ZERO weight.