How much weight? Switching from jacket style to Backplate/Wing

[lowwall]

Colloquial speech. I doubt anyone misunderstood.

Also not correct for me. About half the reduction in required lead weighting (happy?) came from removing the jacket's bouyant nylon, plastic and padding. The rest was adding the steel.

 

[Bob DBF]

Colloquial speech. I doubt anyone misunderstood.

The issue with colloquial speech is that it very well get in the way of the OP's understanding of exactly what is happening with the weight. I would not assume a new diver knows the intricacies of weighting, and it is a disservice not to explain whether you are shifting ballast weight or actually removing the weight.


Bob

 

[lowwall]

But that's the way people actually say it. I suspect it may be more confusing to use non-standard terminology.

But I shall strive to be precise.

When wearing my Zeagle Ranger, size XL, I needed to carry 12 pounds of lead weights* to be neutrally buoyant at 10' with an AL80 tank containing 600psi of air while wearing a 3/2mm wetsuit in salt water. After switching to a DSS stainless steel backplate and wing, I only needed to carry 4 pounds of lead to be neutrally buoyant under the same conditions.

*Actually, I only needed 11, but I wanted to carry the same amount on each side.

 

[dmaziuk]

*Actually, I only needed 11, but I wanted to carry the same amount on each side.

So assuming Tobin's plate weighs 6 lbs, you only "lost" about one pound?

 

[lowwall]

From the horse's mouth:

4.7 lbs is the actual mass.

Stainless Steel is 495 lbs / cu ft. Water is ~63 lbs / cu ft.

When displacing water the plate offers 4.7 * [(495 - 63 )/ 495] = 4.10 lbs.

edit: the density of the water in the Caribbean sea is closer to 63.9 lbs/ cu ft, so you can take off another hundredth of a pound. Approximately.

 

[dmaziuk]

Now you're talking. Yes, I'll buy 3 lbs lost to all that "nylon and plastic and padding". (You do realise that the difference between "I dropped 8 pounds" and 3 is like 266% of course.)

 

[lowwall]

I mentioned the buoyancy of the jacket twice in the post you were objecting to.

I do try to include the relevant caveats. Keeps me off Twitter.

 

[M-Cameron]

accounting for the weight of my plate....my weight stayed the same....

with a jacket BCD i was in 35lbs of lead......in a backplate i was in 30lbs of lead + 5lbs of backplate.

 

[NothingClever]

Another vote for SS BP. I considered purchasing an AL BP for travel but I’ve traveled enough with my SS that I no longer see the marked advantage of an AL BP. Plus I like not having to fiddle with boat weights (remembering to add or turn in).