Figuring for weighting changes with different gear

[tealdive]

All -

Was wondering if there's a basic rule of thumb on changing from a jacket style BCD to BP/W and how it affects your weighting? Specifically amount.

Properly weighted in my rental BCD I carry 30lbs. 7mm wet suit. As I am purchasing my own gear and knowing I will go BP/W - I was wondering if there's an easy conversion to at the least, get me in the ball park?

BP/W should displace a lot less water than a honkin jacket BCD so I should need less weight to be properly weighted. (unless I am dorked up in my thinking on that)

I'm thinking of a SS plate for the 6lbs there with a regulation Hog harness. Again 7mm wetsuit in fresh water. Al 80 for a dive cylinder.

Thanks for the help

 

[Rascally Rabbit]

Nope, no rule of thumb. Each wetsuit is slightly different in the cut and quality of the neoprene and each persons body is different. Get in the water do your weight checks and see what you actually need to perform a safety stop at 10 feet with 500 PSI as these are bare minimums. Don't do this after a dive. Empty a tank down to this and swim it down or use extra weight and hand it to a buddy. This way you aren't testing with excess nitrogen in your system and can safely surface immediately if you can't maintain depth.

 

[TSandM]

If all you are changing is from a jacket BC to a backplate, you can certainly take off the weight of the backplate (5 or 6 lbs) and probably an additional 2 to 3 lbs, depending on which BC you were previously using. Most BCs are a little positive, ranging from 1 to 3 lbs.

 

[Bubbletrubble]

If all you are changing is from a jacket BC to a backplate, you can certainly take off the weight of the backplate (5 or 6 lbs) and probably an additional 2 to 3 lbs, depending on which BC you were previously using. Most BCs are a little positive, ranging from 1 to 3 lbs.

+1. So you should be able to take off 7-9 lbs. of lead (new total of 21-23 lbs. of lead).

This assumes that the only thing you are changing is your BC. If you change your wetsuit, tank, or move from fresh to salt water (or vice versa), then you really shouldn't expect the above estimate to be accurate.

There is no substitute for an in-water weight check once you get all of your new gear.

 

[vladimir]

I just did this exercise in reverse, when I left my backplate home and rented a fairly sleek Scubapro vest. I had to add 6 pounds to my weightbelt--and I had to wear it, which I don't normally do.

 

[Eric Sedletzky]

It's amazing how much weight you can shed by going BP/W.
Take off 6 Lbs. to allow for the plate (s/s)
Take off 2 to 5 lbs. depending on what jacket you had. Jackets have a lot of padding that requires a disgusting amount of weight to offset.
If you are going to a steel tank from AL you can drop another 3 to 5 lbs.
If you were overweighted in any way shape or form in your old configuration then you will just be carrying over the same problem.
You should be able to hold a stop at 15 feet at the end of a full length dive with no air in your BC and control your stop with your breathing alone. If you can do this then your weighting is right on. If you need to put a bunch of air in your bc to be able to hold a 15 foot stop with a near empty tank then you need to re-evaluate your weighting.
Once you get all this figured out it is pure effortless heaven.

 

[vinegarbiscuit]

I trimmed off over a pound. In a 3mm wetsuit with an Al80 tank (no hood or anything like that), I used about 8 lb in a jacket BC. I dropped to under 7 lb when I switched to a 4.7 lb stainless steel plate and STAs (about 1 lb each). It sure is nice not to have to wear any weight in a belt or a harness (it's a balanced rig, so no worries swimming it up to the surface in case of BC failure).

 

[spectrum]

If all you are changing is from a jacket BC to a backplate, you can certainly take off the weight of the backplate (5 or 6 lbs) and probably an additional 2 to 3 lbs, depending on which BC you were previously using. Most BCs are a little positive, ranging from 1 to 3 lbs.

That was pretty much my experience. As BCs go I never considered my Sherwood Avid to be especially buoyant. The extra 2-3 pounds I was able to drop in addition to the late weight was icing on the cake. The weight of the plate is really just weight being moved but that buoyancy offset is pure delight.

Pete

 

[tealdive]

Thanks for the insight. I appreciate it. Just needed a zip code to nail down the address later so to speak. I find myself aligning more and more with a DIR way of diving so I am really looking forward to a BP/W and seeing the changes. Still haven't figured why "they" don't recommend an steel cylinder with a wetsuit (just haven't seen it explained really) but that's small potatoes for now...

 

[Bubbletrubble]

Still haven't figured why "they" don't recommend an steel cylinder with a wetsuit (just haven't seen it explained really) but that's small potatoes for now...

@tealdive: Here's the link to an article entitled "Weighting: In Search of a Balanced Rig" on the DIR Explorers website.