Weight Change with new Steel tanks

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seaseadee

Contributor
Messages
281
Reaction score
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Location
Boca Raton, Florida, United States
# of dives
100 - 199
I am a new diver with an equipment question. My current equipment configuration is thus:
1. 3mil Wet Suit
2. back-inflate BCD with 4 lbs in the trim pockets and 6lbs in the integrated weight pockets
3. Rental Aluminum 80 tanks


I live on the Florida coast so all of my diving is in salt water. With this configuration I am very comfortable in the water with what I consider to be good buoyancy control and good trim. I have just purchased a set of Faber Blue Steel LP85's from my LDS. Faber lists the buoyancy characteristics of these as -3.8lbs full and +2.82lbs empty. The folks at the LDS inform me that most people are able to lose 4-6lbs when switching to these tanks. Since my only gear change is going to be these tanks, I am having trouble understanding how I might be able to drop said 4-6lbs. Here is the thought process: The Rental Luxfor AL80's are -1.4lbs full and +4.4 empty. This seems to be a 2lb difference at both ends of the dive. Am I being two simplistic in my calculations? Also, my LDS overfills these to 3000psi to give me the maximum air time. I do not know if this factors into the equation as the larger amount of air would also weigh more.
 
You should be able to drop 4-6lbs of lead. LOL
 
Why not start out by taking 2 lb out of either the trim or integrated weight pockets and see how it goes? I can't see losing 4-6 lbs with this switch unless you're too heavy to start with. Even if your LDS gives you a nice overfill, the tanks will still weigh the same at the end of the dive, and you will need enough weight to hold a stop with them nearly empty.
 
I am a new diver with an equipment question. My current equipment configuration is thus:
1. 3mil Wet Suit
2. back-inflate BCD with 4 lbs in the trim pockets and 6lbs in the integrated weight pockets
3. Rental Aluminum 80 tanks


I live on the Florida coast so all of my diving is in salt water. With this configuration I am very comfortable in the water with what I consider to be good buoyancy control and good trim. I have just purchased a set of Faber Blue Steel LP85's from my LDS. Faber lists the buoyancy characteristics of these as -3.8lbs full and +2.82lbs empty. The folks at the LDS inform me that most people are able to lose 4-6lbs when switching to these tanks. Since my only gear change is going to be these tanks, I am having trouble understanding how I might be able to drop said 4-6lbs. Here is the thought process: The Rental Luxfor AL80's are -1.4lbs full and +4.4 empty. This seems to be a 2lb difference at both ends of the dive. Am I being two simplistic in my calculations? Also, my LDS overfills these to 3000psi to give me the maximum air time. I do not know if this factors into the equation as the larger amount of air would also weigh more.

I think you have your figures off here and the LDS is wrong, Steels are not positive when empty, they are still negative, so steels start negative and end negative. So I think the figures you are quoting for the Fabers are wrong.

In contrast Ali's are positive empty and negative full so you have a greater buoyancy swing. - I have tried to look up the LP85's and can't see the figures at the moment.

But that will be where the confusion is coming in, I agree you should be able to drop a few pounds. - Phil
 
Remember that it is more important to be neutral at the end of your dive . If you drop 6lbs of lead and dive with an overfilled tank you may find that you are a bit light at the safety stop. I would just start with dropping 4 lbs out of the weight pockets(not the trim ) and do some trial and error on shallower dives. If you are still needing air in your bc at the safety stop with a 500psi tank, drop the other 2 lbs
 
The figures for the Fabers look right, the Worthingtons are heavier and stay negative though out.
 
Just looked at your link and the buoyancy quoted is for an empty naked tank I.e. No post and valve. You will have to add 1.5-2 lb for the post and valve, and then factor in the 50 bar air you are leaving as your safety limit. I think this will still make this tank negative at the end of the dive. Phil



Sent from my iPad using Tapatalk
 
Just looked at your link and the buoyancy quoted is for an empty naked tank I.e. No post and valve. You will have to add 1.5-2 lb for the post and valve, and then factor in the 50 bar air you are leaving as your safety limit. I think this will still make this tank negative at the end of the dive. Phil



Sent from my iPad using Tapatalk

Ok now that would make sense. If I take the empty buoyancy of +2.8lbs add -2.0 for the post and valve and another -1.0 for my reserve then I would be -0.2lbs at the end of the dive. The luxfor's are +3.4 at 500psi, so I should be able to drop 4lbs and still be neutral at the end of the dive. I will do as someone else suggested and start with dropping 4lbs from my integrated weights and see what happens at my safety stop.

Thanks to everyone for their help.


Sent from my iPad using Tapatalk
 
I think most people are thinking of the Faber FX series when going to steel. I did it and in south florida dropped 6lbs of my weight. I think you are going to be correct with dropping 2 pounds.
 
https://www.shearwater.com/products/peregrine/

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