Tanks and weighting

[W W Meixner]

How much are you wearing in the way of undergarments. I use 14 lbs total ballast weight (tank, plate, lead, etc..) when in my moderate underwear that i wear in 40’s F water. Though the OP seems overweighted with 30lbs, he did state he was wearing 3 undergarments of undisclosed thickness for undisclosed temps. So doubles may not be enough ballast in his case.

B...

I have one under-garment system...two piece/low loft T-Max Heat/+ T-Max Heat socks...if the water is in the 38/42 DF range...I have a merino wool long sleeve top that I'll wear as a booster...my suit is a DUI CF-200 Signature series/proprietary crushed neoprene...

My dives...130' +/-...cold Ontario Great Lakes water...usually in the 45 minute range...nice and warm...

I've had this discussion many times...dry-suits are not buoyant...air trapped in poorly fitting dry-suits...is the problem...some divers never correct the problem and live with the ballast...I'd rather not...I shudder when I see a diver on a charter with monster doubles...a ''far too large'' drysuit heavily wrinkled from top to bottom...looking like a Shar Pei puppy...and wearing a fully loaded weight belt..

The attached is my suit of choice...and how my suit fits me ...even with a feather-lite rebreather...I never wore more than 24 pounds of ballast...the second photo is me last year...cold Georgian Bay on the Arabia...24 pounds of ballast...cylinders are a 3AL 50/3AL 19...

I only have gas in my wing on the surface post ascent...and on the surface pre descent...during the dive my wing is always empty...I use my suit to stabilize trim and desired depth...and it doesn't take much...a couple quick shots on the chest inflator...

If I was a technical diver with a full load of travel/bottom/stage/deco cylinders...it would be a different story...one that I'll never have to concern myself with...

Best...

Warren

 

[Paul M]

I just went diving last Saturday and I had 28# of lead. I had on a fourth element j2 too and bottom, fourth element xerotherm tip and bottom and fourth element arctic top and bottom. Fourth element xerotherm socks and arctic socks and then the xerotherm glove liners. Drysuit is a 4x apeks kvr1 I’m 6’3 220lbs. And when my tank got to abut 1700 psi I could feel myself wanting to go up. My wing was empty the whole dive. The only air I added was to my drysuit. I had to keep adjusting my drysuit air the rest of the dive and near the end my drysuit was almost empty. In the beginning of the dive my tank was 2600 psi and I was perfect. Still no air in my wing just added air to my drysuit to remove the squeeze and that was enough. That was with a HP100 and steel back plate. Just for an idea.

Similar to you, I wear Fourth Element Arctics with a couple additional lighter layers underneath. I have a trilam DUI drysuit. I use a pair of Faber steel 100's.
I will basically just repeat whats been said:
The best, easiest way you're going to find out what you need is to find neutral buoyancy at ~20ft.
- tank(s) at min reserve pressure
- just enough air to take the squeeze out of your dry suit. Be sure no air is 'hiding' somewhere like your legs/feet. Go semi vertical for a couple seconds if needed then get back in horizontal trim.
- no air in your bcd

The thing about steel tanks, more so than Ali's is that we're always over-weighted at the start with full tanks. Not much we can do about it. Just don't be over-weighted at reserve.

Me personally, with a drysuit and cold, cold water undergarments:
- 2 Faber Steel HP100's, Sidemount rig, I need ~5lbs lead to be neutral at reserve.
- 1 Faber Steel HP100, Carbon fiber backplate rig, I need ~14lbs

Cheers

 

[victorzamora]

And when my tank got to abut 1700 psi I could feel myself wanting to go up.

So you're underweighted by a couple of pounds if your drysuit has just enough gas to remove the squeeze (how you should be diving it). You want to be able to still stay down while comfortable in your drysuit with 500psi or less.

In the beginning of the dive my tank was 2600 psi and I was perfect. Still no air in my wing just added air to my drysuit to remove the squeeze and that was enough.

Yeah, sounds like you're underweighted slightly. I'd bet 2-4lbs, unless you've got way too much gas in your drysuit.

That was with a HP100 and steel back plate. Just for an idea

So you're not likely going to be changing your BCD too dramatically. Knowing what you said above gives me cause to think you're underweighted already. When you move to doubles, I'd start out with the same amount of lead you've got now.

Run the tanks down to nearly-empty, empty your wing, go to 15ft with just enough gas in your suit to remove the squeeze. If you sink, take 2lbs off. If you sink FAST, take 4lbs off. If you're still struggling, consider adding some more.

 

[Bowers]

I like to weight check without scuba. Don the drysuit, hop in a pool, let out the air to the normal light squeeze, then grab weights until you bob around on a full breath but sink when you exhale (make sure you can either drop the weight or kick off the bottom since you’ll be breath holding). Once you know the perfect amount of weight you need, just start subtracting the buoyant weight of your tanks and other gear, to tell you how much of that weight needs to be lead. That way you can easily get pretty darn close to the right amount every time, even before doing a predive weight check.

 

[seeker242]

he told me if I go to two tanks I will probably not need any weigh either.

If 30lbs is not actually over weighted to begin with, I'll bet he's dead wrong. There is no way that a single hp100, band, reg and manifold can make up for dropping 30 lbs.

 

[PBcatfish]

I dive with a lot of different gear sets. I have recorded the buoyancy of each piece of major gear that I own. a 2mm vest is +2#, a 3mm full suit is +10#, an AL80 tank is +4#, most of my steel tanks are around -2#. I use these numbers in conjunction with my natural buoyancy amount sans gear, to determine how much lead to bring on each trip. I also bring an extra 2 pounds just in case I missed by a little or had a rounding error. So far, I haven't missed. The tank number are based on their empty buoyancy at a 15ft safety stop.