Weighting for tropical diving with SS BP/W

[Green Frog]

I just discovered this thread and am reading it with great interest. I am 5’10” and am now hovering right around 190# (down from 235!) Since I “shrank” so much, my old X Lg vest type BCD is way too big, so I bought an aluminum Dive Rite Back Plate with Oxy Cheq wing. On my June trip to Nassau, I dove my old BCD with 10# of hard weights, but since the BP/W is heavier than the BCD, I’m figuring I’ll be able to get in a pool session to get close. Long and short of it, you guys are giving me ideas I need to get started. Thanks!

 

[wetb4igetinthewater]

I'm around 200, 5'10", could afford to lose a few pounds (180 would be about right).

With an AL80, a 5 mil, SS BP/STA, neutral fins, I don't need any additional weight and I trim out nicely.

 

[NorCalDM]

I'm 6' 190# and with my aluminum plate and 5mil wetsuit I add 8# of lead for salt water. Aluminum plate and 3mil wetsuit I add 4# of lead for salt water, anything less than a 3mil 0# of added lead.

 

[lowwall]

Just a note. A person's overall weight has only a limited correlation with lead requirements. At least unless you know the body fat percentage as well. Body fat has a density of around .9 (g/cc), while everything else averages out to about 1.06.

So if we take a 100kg (220lb) person with 25% body fat, we get 75x.06=4.5kg negative and 25x.1=2.5kg positive. For a net of 1kg positive. But then we have to add in 2kg positive for the typical amount of air that is left in the lungs after a normal exhale, so 3kg (6.6 pounds) positive before taking into account your gear.

Edit: This is for fresh water. Seawater has a density of around 1.027 g/cc, so every pound/kilo of lean mass contributes .033 pounds/kilos of negative bouyancy and every pound/kilo of fat contributes .127 positive.

For @Green Frog . If all of the 45 pounds you lost was fat (congrats!), you should be able to remove 5.5 pounds of lead (in the ocean). Your aluminum plate will add just over 1 pound negative, so that's 6.5 you can take off. The unknown is how positively buoyant your old BCD was. You might not need any lead in the pool and I suspect you'll only need 2-4 pounds in the ocean, but I'd start with 6 pounds and do a weight check at your safety stop.

 

[Green Frog]

To low wall and others contributing so much to the conversation, thanks! As near as I can determine, the Al BP/W is about 1.5# heavier than my old vest-type BCD. I had already lost the weight before I went to Nassau, but I’m afraid I lost a fair amount of muscle mass along with the “stored energy” (to avoid using the “F word”!) so I think I should be able to look at about 4-6# and be in the ball park.

I’m hoping to take an early Spring dive trip to the Keys so I can drive and take a big load of gear then hope to do a dock dive to tune up my weight and trim. The 2 XS Scuba trim pockets on the waist band and the 2 on my cam band on my tank will each hold a 5# hard weight (or smaller) so I could go with no weight up to 20#. I’m diving an old tri-lam skin that contributes minimal buoyancy, but if I add a shorty or a full 3mm suit, I’ll deal with that when it occurs. Basically I don’t like to dive in cold water though!

As a backup plan, I’ve rehabbed an old ScubaPro Accent to use if I have to abandon the BP/W for whatever reason. I do have plenty of hard weights for the trusty old weight belt. Luckily my SUV has room to haul all of it.

Thanks again everybody!
Froggie

 

[FreqFlier]

Hawaii is warmish water not warm water and I now use a 5mm full suit year around there and you will see guides there in 7/8mm in the winter. Current water temperature is 80F.

+1

I've been in Oahu/Maui 3 times around mid October, 3mm barely cut it. Water temps 74-79F. I don't have 5mm and felt like taking 7mm to Hawaii was a bit too much.

6'2", 225, 3mm, ALU Xdeep plate, neutral fins I needed about 6lbs in Hawaii

On a boat - especially when your weight attachment is somewhat tricky - put 2# extra just in case so you don't waste anybody's time on your first dive. It'll help you a lot (assuming Cathedrals is your first? )

 

[Rox1731]

I use Quick weights and attach them to my shoulder straps. Trimmable and dumpable.

View attachment 801334

Did not know about these, thanks!

 

[wetb4igetinthewater]

I use Quick weights and attach them to my shoulder straps. Trimmable and dumpable.

View attachment 801334

I didn't notice this before, but this is pretty slick! I take it this is for 2" webbing? @MAKO Spearguns , is that correct?

EDIT: Nevermind. Found my answer here: Quick Weights. Clever design!

 

[gordonscuba]

I would rather have a long, narrow weight in my STA than normal lead weights zip-tied onto holes in my backplate:

Halcyon Dive Systems

Halcyon began as a group of divers who knew exactly what they wanted, but could not find it in any dive store. Our passion for diving led us to designing wings and lights to satisfy ourselves.

halcyon.net

 

[happy-diver]

Lead flashing is my preferred weighting system