Weighting advice Needed!

[DiveRef]

Needing some advice, I am 6'5" 315Lbs. I dive a Faber Hp133 Tank and its characteristics are WEIGHT EMPTY: 42.7 lbs. BUOYANCY FULL: - 9.08 lbs. BUOYANCY EMPTY: 1.45 lbs. I did some weight checks today in my pool (saltwater) Using just the Tank and my BC (jacket style) I need no weight and at 500 PSI I float just below eye level with a normal held breath. Now WITHOUT BC or Tank, Using a Farmer john I need 12 lbs to float eye level, and using a long sleeve Shorty it takes 16 lbs to float Eye level, and using the whole suit it took 31 lbs to get to eye level. With the numbers from the tank I could theoretically cut 8 lbs off of all of those numbers when I put my full rig on? For instance if I were to dive the Long sleeve shorty I would be able to dive 7 lbs total?

Thank you for the insight and help!

 

[tbone1004]

no, you have to use buoyancy empty figures. If you're neutral at 500psi with just the tank and bc, then you need every bit of that 31lbs. Where did you get 8lbs from? The tank contains 10.5lbs of air....

At your height, I'd seriously consider moving to a bpw though. The long pattern DSS rig in SS with the optional weight plates would give you about 18lbs of ballast just on the backplate and might actually get a bit more since most jacket bc's float.

 

[Kharon]

Guessing will usually only get you close and sometimes not even close. The only way to know is to do a weight check with the entire kit you will be diving.

I layer - I have 2 polyolefin full suits, a 3mm vest, a 3 mm fullsuit, 2 different pairs of boots, 2 different hoods, 2 different gloves. I took a tank that had 500psi and did weight checks with every combination that I would use. It too an hour or two but I now have actual weight data for whatever kit I would wear.

Each spring I only have to verify the weight of one kit to make sure my body's buoyancy hasen't changed. If it did, that one weight check gives me an offset for every kit.

 

[DiveRef]

I thought the Tanks Full buoyancy -9.08 lbs minus the empty 1.45 was weight you could potentially take off your belt? Guess I am getting wet again this weekend....

 

[tbone1004]

Kharon, you took the hard route on that one mate.... Need a weight belt, mesh bag, and a luggage scale, scuba kit with any tank at any pressure

Weigh yourself, easiest if you have a long hose because you don't want anything strapped to you. Figure out your the buoyancy of your body.

Weigh your kit, again, doesn't matter how much air is in the rig you can calculate that out, this is where the luggage scale comes in. Doesn't matter if it's an empty AL30 or a full HP133, you weigh the rig, and subtract the weight of the gas. Al80 at 3000psi means you subtract 6.2lbs

Weigh your exposure protection in whatever combo you wear it. Put it in the mesh bag and add weight until it just starts to sink, make sure you get all of the air out of any nooks and crannies in the kit. Now you know how positive each exposure combo is, you know your ballast, and your rigs ballast. You+rig+exposure combo=total weight required. Little more difficult in a drysuit, but not all that bad. Doing full weight checks in your rig at 500psi is just too much effort.

Full buoyancy specs don't matter in anything except wing lift calculations. Dry weight doesn't matter at all, buoyancy empty is the only spec that matters, but that number is without a valve, so you have to know how much your valve weighs. Why it is best to get your "rig" weight, and then subtract the weight of the gas in the tank. .08lbs/cf