Question regarding BP/W weighting "issue"

[Steve02]

Tonight was a pretry exciting night - I took my new BP/W into the water (pool) for the first time.

To keep the buoyancy similiar to what I normally dive, I wore my 3mm full suit. When I was renting jackets and back inflates I would need to wear 12 pounds. Tonight in the pool I sank to bottom with no weight and a fully deflated wing. All dives have been done with an AL80, including tonights.

Is this dramatic of a change in weight normal?

I was thinking about eventually getting a HP120, but until I figure something out about the weighting issue, I may just sit tight.

Thanks,
Steve

BTW - I love how the BP/W feels compared to traditional BC's.

 

[dumpsterDiver]

yes it is normal

 

[spectrum]

Well tonight you had a full cylinder I assume so that accounts for a good 5 pounds. Then the plate goes for 4-5 on it's own. More with a full STA. Finally you probably had 2-3 pounds of buoyancy in the form of padding in the old jacket. So yea that sounds about right except 5 probably needs to go back on so you aren't too light at the end of a real dive.

Being in OH I'll assume this an all fresh water discussion.

Pete

 

[TEArrington]

If your backplate is stainless steel, I think that's about 6 lbs. If you have a weighted single tank adapter, that's several more lbs. So, it's not all weight drop, so much as weight shift to a location closer to your tank. Pretty cool, huh? I am just now switching too, even though my friends have been suggesting it for a year. It is pretty nice.

You might want to try it out in open water a couple of times before you decide on more equipment. That way you can really see if you have to make any adjustments to keep proper trim and buoyancy control, since the type of water you dive in also makes a difference.

 

[Gombessa]

That sounds pretty close. if your BP is steel, then your BP/W rig is probably about 6-7lb negative. A full AL80 is about 2lb negative. That 8-9lb is more than enough to sink a typical 3mm wetsuit without additional lead, especially in freshwater.

On the other hand, a typical jacket BC is anywhere from 2-3lb positive (due to all the padding), which leaves your entire 3mm suit unaccounted for, which is why you can float all day in it if you don't add any extra weight.

 

[gcbryan]

I would assume that he always has a full tank so that's not at issue. It's a matter of the SS BP, no padding and STA (if any).

To the OP do you have a STA?

 

[Steve02]

Cool!! Thank you all for the quick and thoughtful responses. It was really neat to be able to dive without any added weight.

Yes, the BP is stainless steel, no STA. I ended up getting a large from DSS.

All of my local diving will be fresh water, salt water only on vacations.

 

[Gombessa]

I would assume that he always has a full tank so that's not at issue.

I was thinking more in terms of absolute buoyancy. The OP was able to sink with a BP/W and full tank but that doesn't necessarily mean he has enough weight for the dive (depending on the rest of his configuration, that could be where the "extra" 3-4lb of lead comes in while using his BC). Of course, as a new diver he could easily have been overweighted with the BC.

 

[spectrum]

I would assume that he always has a full tank so that's not at issue. It's a matter of the SS BP, no padding and STA (if any).

To the OP do you have a STA?

I should hope that his optimal weight is based on a near empty cylinder. Since he's trying to understand why he is now so far from neutral I'm not going to make that assumption.

 

[sk001]

People usually switching find they use less or no weights. For a 3mill wetsuit I usually use no weights if I carry a can light or two pounds without. I can get by on no weigys bit the extra two Pounds makes the 1m stops a little easier. However that's with a alu Bp. Not surprised you dropped like a brick with the steel bp.