Quickie Weight Check for an upcoming trip

[bkotheimer]

Tobin:

I don't know if you really like doing these, but it's great when you do! Just trying to see if you agree with this....

Bahamas (not that location matters)
79 degree F salt water (not that the temp matters either)

Diver: 140', 5'9" (sinker)

Stainless steel DSS backplate w/Torus26
No pony, no can light, no stages, no scooter, neutral video rig
AL80@3000psi

4/3mm wetsuit (surf suit with about 20 dives on it)
1 mil beanie
3 mil booties
no gloves or 2mil gloves
Fins- APS Mantarays (positively buoyant)

Additional weight: 6 lbs ALL ON CAM BANDS (no belt)
Total with BP+reg = approx. 12 lbs., all non-ditchable

This is the ballpark figure, and I will of course do a surface check with 3000psi in my AL80 to make sure I float at eye level with an empty wing.....

HOWEVER, my plan is to NOT add additional weight for the AL80 based on the assumption that the compression of the 4/3 at safety stop depth will more-or-less offset the change in buoyancy when the AL80 gets to 500psi.

Does this look about right?

Thanks!

 

[cool_hardware52]

Tobin:

I don't know if you really like doing these, but it's great when you do! Just trying to see if you agree with this....

Bahamas (not that location matters)
79 degree F salt water (not that the temp matters either)

Diver: 140', 5'9" (sinker)

Stainless steel DSS backplate w/Torus26
No pony, no can light, no stages, no scooter, neutral video rig
AL80@3000psi

4/3mm wetsuit (surf suit with about 20 dives on it)
1 mil beanie
3 mil booties
no gloves or 2mil gloves
Fins- APS Mantarays (positively buoyant)

Additional weight: 6 lbs ALL ON CAM BANDS (no belt)
Total with BP+reg = approx. 12 lbs., all non-ditchable

This is the ballpark figure, and I will of course do a surface check with 3000psi in my AL80 to make sure I float at eye level with an empty wing.....

HOWEVER, my plan is to NOT add additional weight for the AL80 based on the assumption that the compression of the 4/3 at safety stop depth will more-or-less offset the change in buoyancy when the AL80 gets to 500psi.

Does this look about right?

Thanks!

Sounds over weighted to me.

Your suit is likely 4-5 lbs positive, and an empty al 80 is +4. That means you need about 8~9 lbs of total ballast.

Your plate and harness provides about 6 lbs and your reg provides about 2 lbs.

We have many customers who use only their SS plate, harness and reg for ballast when diving in thin suits and al 80's.

Tobin

 

[bkotheimer]

Even better. I'll use little - if any - additional lead for the initial weight check. Then I'll add a couple lbs only if needed.

I was basing this on using 4 lbs of lead for my 3/2 last time I used it (interpolated to 6 for the 4/3), but - who knows? - maybe I was overweighted then. I'm learning to use less ballast all the time, and I've yet to blow a safety stop due to being underweighted (!)

Thanks!

 

[bkotheimer]

Well, as a followup...

My 4/3 must be "floatier" than expected, because 5# of additional lead ended up being the magic number for some reason (odd 1# on my waist belt, dead center). Granted, my camera rig was maybe half a lb positive the way I had it set up, but the rest of the buoyancy was just this medium-weight surf suit. I'm puzzled, too -- I'm a really skinny guy, and I simply could NOT stay down with less than 5 once I hit <1000 psi.

I am sure all the air was out of my Torus. You make these SO easy to dump air from.

Anyway, it was pleasant diving... great time in the Bahamas. Saw you at the Scuba Show yesterday - good booth location.