Buoyancy and Weights

[Bowcaps]

So for most of this year I’ve been diving using rental gear a Cressi start bcd and Cressi regs, often diving in just a rash vest and board shorts. The weight handed out by the dive center was 15lbs, I’m a big lad 6’4” and stocky and the weight seemed to be ok.

I’ve recently bought my own gear a hydros pro bcd and Scubapro regs (G25 + A700). I thought it best to get an idea of buoyancy and weights, so I used my local pool and added a 3mm shorty.

I started with 12lbs as this was fresh water and sank like a rock, after a period of adjusting weights and which pockets to put them in, I came up with about 3 and a half pounds.

I realise this is fresh water, but it’s almost a 12lb reduction and I’m in a shorty wetsuit.

My question : Is this normal, or could I be doing something wrong? It just seems a massive drop in necessary weights.

Also only having a few lbs of weight it was challenging to trim the bcd, I managed to get a good diced trim, but the surface trim was pushing slightly forward.

I’m going to give it another go in the pool before heading out to the coast, but using my 3-4mm full wetsuit this time. Any suggestions appreciated.

Thanks

Bowcaps

 

[lexvil]

There is a lot of float in the jacket type b/c from the padding, the Hydros is neutral in a larger size jacket this can account for 4 or more lb.

salt water will take more lead as will the full suit, a guess is you’ll need 8 to 12 lb in salt and do a proper weight check and adjust as necessary once there.

for the pushing forward try a little less air in the b/c.

 

[inquis]

You will have a 6-7 lbs difference between salt and fresh, assuming you weigh 210-250 lbs. (That's based on average salt water density.)

15 lbs sounds heavy to me in a rash guard, even allowing for a floaty cressi BCD. Had you recently done a proper weight check (tank around 500 psi, empty BC)? While that weight may have been needed when first starting, it's very common for required weight to drop as comfort increases and breathing improves.

Regardless, if you can hover in the pool now with 3.5 lb + reserve tank pressure + EMPTY BC, that is a good weight with that suit/gear. I would guess another 2-3 lb with a full suit, but checking that in the pool is good confirmation.

One trick if you find yourself neutral with empty BC but with more than reserve air, just add lead accordingly. For an AL80 tank, each 500 psi weighs 1 lb. For example, if you are neutral at 1500 psi, then you need to add 2 lb lead.

Knowing this, you can quickly dial in the total lead with a full tank (& empty BC) by holding a weight belt and adding bricks until becoming neutral (easily ascend/descend with breath alone). Proper weight is 5 lbs more (again, for an AL80 around 3000 psi). Spend the rest of the time distributing the lead for better trim. Tip: flood your wetsuit first by letting water in at the neck.

 

[Boarderguy]

Don't forget to include the weight of air in your tank. 3.5 lbs with a full tank isn't necessarily going to keep you at your stop with ~500 psi. Call it 10-12 lbs for salt water and trim down from there.