Not the same SS vs Aluminum question

[RIHappyDiver]

I am toying with switching to a DGX bp/w set and am hung up on the SS vs aluminum choice, but not due to adding too much overall weight. Background; I currently dive with a back inflate BC and have LP 85s and a M series HP 100 for tanks. There are a couple of local shore dives that require a bit of a swim out (approximately 200 yards on one of them) which we generally do on our backs. This gives me no trouble with the 85s, but the 100 causes me grief. Even with the bc fully inflated it feels like the 100 is pulling down hard and makes it difficult to catch my breath. My fear is that a SS plate will lead to the 85s having the same affect. Any advise and guidance would be greatly appreciated. And, yes, selling the m series and getting a standard Fabre 100 has crossed my mind.

Erik

 

[Prometheanfire]

Do you dive a wetsuit? If not, add some bouyancy / sun protection could work.

 

[lexvil]

If you’re overweighted already it doesn’t make any difference, use less weight for the 100

 

[RIHappyDiver]

@Prometheanfire, got that covered. Depending on the time of year it’s a 5 mil at the lightest, though usually with a hooded chicken vest, and a 7 with hood at the most.

@lexvil, I spent my first 2 summers back into diving working on that and I might still be able to drop a pound or 2, but I’m currently only diving 16# with the 7 mil and hood with the 100. I’m usually the last one down when we drop from the surface. The real kick to this is that I can lay on the surface face down breathing off my reg and not have this problem.

 

[lexvil]

@Prometheanfire, got that covered. Depending on the time of year it’s a 5 mil at the lightest, though usually with a hooded chicken vest, and a 7 with hood at the most.

@lexvil, I spent my first 2 summers back into diving working on that and I might still be able to drop a pound or 2, but I’m currently only diving 16# with the 7 mil and hood with the 100. I’m usually the last one down when we drop from the surface. The real kick to this is that I can lay on the surface face down breathing off my reg and not have this problem.

If you need 16lb with the 85 and all is cool but with the 100 you’re having trouble staying on the surface, all based on what you’ve said here, you need to remove weight for the 100.

 

[RIHappyDiver]

If you need 16lb with the 85 and all is cool but with the 100 you’re having trouble staying on the surface, all based on what you’ve said here, you need to remove weight for the 100.

Sorry, I should have been more clear. With the 85 I need 22#, 16# with the 100. Also, I’m not having trouble staying on the surface. If I stop swimming and just lie on my back I float, but I still feel the pressure of what I am assuming is the tank on my chest from the straps. Otherwise the 2 tanks handle exactly the same with the weights listed above, and give me no trouble at all. I don’t understand it, as the buoyancy should be the same with the change in weights. But, for some reason, the weight being on my back (the 100) as opposed to on my waist (the additional 6#) makes a difference.

 

[lowwall]

Most of us are more comfortable with weight on our backs than on a belt. I wonder if there's something about your current BCs harness system that is causing the discomfort in that position.

I suspect this will go away when using the wide webbing that is standard with a backplate harness. FWIW, I haven't had any comfort issues swimming on my back with a steel backplate, standard harness, and tanks varying from an AL80 to an HP120. Is there any way you can try one out before you buy?

 

[RIHappyDiver]

@lexvil , reading through my response made my think of a question that I’m surprised I hadn’t thought of before. Is the M series either top or butt heavy? At -14.7 pounds of buoyancy it would seem that either one might cause what I’m experiencing. I may be completely wrong, and I won’t be able to verify it for awhile due to the cold weather, but now I’m curious.

 

[lexvil]

Sorry, I should have been more clear. With the 85 I need 22#, 16# with the 100. Also, I’m not having trouble staying on the surface. If I stop swimming and just lie on my back I float, but I still feel the pressure of what I am assuming is the tank on my chest from the straps. Otherwise the 2 tanks handle exactly the same with the weights listed above, and give me no trouble at all. I don’t understand it, as the buoyancy should be the same with the change in weights. But, for some reason, the weight being on my back (the 100) as opposed to on my waist (the additional 6#) makes a difference.

Ok, the 85’s are not as heavy in the water, they can be pretty bottom light but I’m thinking this be more of a b/c issue like the shoulder straps being to tight? It’s hard to predict the feel difference you’ll have with a backplate over the b/c but overall it should trim out better. Do you have air in the b/c on these swims, assuming you do I don’t think I would be able to feel the tank weight difference.

 

[formernuke]

I'm wondering if it is simply a weight issue. I'm not familiar with those tanks but for example my double lp50's weigh more than a single 100 but need more lead. So although you are compensating for the weight difference your 100 weighs more, perhaps more than 6 pounds more than the 85.

Your actual combined weight is therefore more with the 100. When swimming on your back all the weight is facing down the direction of gravity, therefore you feel it more.

Or maybe it's just me over analyzing physics.