Weighting relative to backplate material

[tbone1004]

even if he only has 3lbs, you're not going to kill yourself being 2lbs over weight, it's not the end of the world, it really is splitting hairs at that point, you just have to get close enough

 

[geoff w]

I really hate reading threads on SB and elsewhere without a final resolution, so here goes. The stainless steel DiveRite XT Lite backplate is brilliant for tropical recreational diving! It's noticeably thinner than the regular DiveRite stainless backplate, which is very obvious when using the same carriage bolts for attaching the single tank adapter and wing, and feels noticeably lighter. The bolts stick a lot further out so if anyone else goes for one, test the bolt length before diving or you might have 2 holes in your back!

I only dove a 1 mm suit, with hood, gloves and booties, in Palau, so couldn't make a one for one comparison to start with. The first dive with 4 lbs lead was fine, but I felt a touch light at the end of the dive doing a safety stop, so I grabbed 1 lb off my wife's weights and sank a lot faster on the next several dives. A few dives later, my wife wanted the 1 lb back, and 1 had no trouble descending from the surface at the end of the dive with a much emptier tank, so 4 lbs was a good weight. I chalk the difference up to even a 1 mm suit loses a little buoyancy after a few dives, and all our gear was saturated with water, so probably no air trapped in fabric or webbing.

After Palau, we spent a few days on Oahu and did a quick shore dive there. I wore a 3mm suit, hood, etc, which essentially put me in the same gear configuration as the last time in tropical water referenced in my original post. I threw on 5 lbs which worked out fine, which is where I was expecting to end up based on everything posted in this thread

The funny thing is I did a night dive at home yesterday. 7mm full suit and hooded vest since the water here is about 20 degrees colder than what I had been diving on vacation, but back to my heavier backplate and very negatively buoyant steel HP80 tank. I only used 2 lbs of lead

 

[Eric Sedletzky]

Only on the internet would we ever see such microscopic brain surgery about weighting. Holy crap!!

 

[fbk]

Only on the internet would we ever see such microscopic brain surgery about weighting. Holy crap!!

I'll say

 

[NAM001]

Wow this is way over thought. the back plates is a wash as displacement goes since the difference is so small. The only thing that counts is the weight of the plates on land. the amount is not inporetant it is the difference of the 2 plates that is.. and that is 3.5#. If you remove 3.5# by changing the plate you need to put it back on in the same place and all is well. I would put on 4# on the tank or bolt it to the plate. The water density thing is a whole other game and only will apply if doing a salt to fresh water change. That conpensation will not change because of the plate change alone. TS&M is right ....... ounces dont count.

 

[Kazeone]

Reading this to the end was the most fun I’ve had all day.

 

[sea_ledford]

... when using the same carriage bolts for attaching the single tank adapter and wing, and feels noticeably lighter.

Wait a minute! You are using single tank adapters?? That wasn't in the initial calculation! And changing bolt lengths will totally throw off your displacement measurement. I think we need to have this entire discussion over again given the new information.

-Chris