With empty wing and suit I cannot swim up a set of 104s full of EAN32 (well at 40' I can get them about 10' off the bottom.)Peo:
Halcyon Backplate Question
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VTernovski
Contributor
Uncle Pug:
UnclePug, so that said, do you not dive these doubles in the open ocean then?
I had the same discussion the other day on my club's board, that I would rather not dive my e8-130's in the open ocean since I can't swim them up. But the argument getting thrown at me was that between a dive buddy, a drysuit, and a lift bag, there is a very little chance for me not to get back on the surface vs. limiting the gas supply...
I want to hear how would you address this topic.
Peo
Registered
Uncle Pug:
Perhaps you are overweighted? That could also explain why you need that extra lift in your wing.
Perhaps I'm just underpowered... I don't use any extra weight other than the 6# SS backplate (and maybe a pound for the light canister) with the double 104s and EAN32.
As for diving in the ocean... yes, I am counting on my wing, drysuit, buddy and liftbag.
As for diving in the ocean... yes, I am counting on my wing, drysuit, buddy and liftbag.
Interesting thread !!
Seems to be 2 related questions are being dealt with in this thread - the choice of an AL vs SS backplate and the choice of the wing size (55# vs 70#).
The key is that we would like to dive a balanced system with proper weighting and that avoids unneccesarily large gas spaces that can contribute to dynamic instability. A larger
wing can also contribute to increased drag which is to be avoided.
Even if the 70# wing provides no additional drag when compared with the 55# wing as Uncle Pug suggests, the 70# wing will contribute to greater dynamic instability by providing a greater volume for the gas to shift in as the divers position is altered.
If you don't need the lift a 55# wing would be a better choice over the 70# wing. For ocean diving in SoCal I find that a 55# wing works well. This includes diving with just doubles (recreational dives), diving with doubles and a single stage or diving with doubles and multiple stages or diving with my Gavin. But the key is diving a balanced system and not being overweighted. I don't carry excess weight and the stages are all Luxfer AL 40s or AL 80s.
You may need both an AL and a SS backplate in your gear bag.
I use both an AL and a SS backplate. Which one I use on a dive is again dependent on the overall balance of the system. Assuming the use of the same drysuit and undergarment, the choice is is largely dependent on the bouyancy characteristics of the tanks and if the diving is to be done in fresh or salt water. In freshwater, I tend to use the AL backplate with steel doubles. In saltwater I tend to use the SS backplate with LP95 and LP104 (or E8-130) doubles and the AL backplate with Scubapro/Faber MP72s (which are more negative then the LP104s). Your mileage may very depending on the balance of your system.
Marc Hall
www.enjoythedive.com
Seems to be 2 related questions are being dealt with in this thread - the choice of an AL vs SS backplate and the choice of the wing size (55# vs 70#).
The key is that we would like to dive a balanced system with proper weighting and that avoids unneccesarily large gas spaces that can contribute to dynamic instability. A larger
wing can also contribute to increased drag which is to be avoided.
Even if the 70# wing provides no additional drag when compared with the 55# wing as Uncle Pug suggests, the 70# wing will contribute to greater dynamic instability by providing a greater volume for the gas to shift in as the divers position is altered.
If you don't need the lift a 55# wing would be a better choice over the 70# wing. For ocean diving in SoCal I find that a 55# wing works well. This includes diving with just doubles (recreational dives), diving with doubles and a single stage or diving with doubles and multiple stages or diving with my Gavin. But the key is diving a balanced system and not being overweighted. I don't carry excess weight and the stages are all Luxfer AL 40s or AL 80s.
You may need both an AL and a SS backplate in your gear bag.
I use both an AL and a SS backplate. Which one I use on a dive is again dependent on the overall balance of the system. Assuming the use of the same drysuit and undergarment, the choice is is largely dependent on the bouyancy characteristics of the tanks and if the diving is to be done in fresh or salt water. In freshwater, I tend to use the AL backplate with steel doubles. In saltwater I tend to use the SS backplate with LP95 and LP104 (or E8-130) doubles and the AL backplate with Scubapro/Faber MP72s (which are more negative then the LP104s). Your mileage may very depending on the balance of your system.
Marc Hall
www.enjoythedive.com
Marc, the few extra inches in length of the 70# vs the 55# isn't going to contribute to *greater dynamic instability*. That idea comes from using your drysuit for BC... there the shift will contribute to dynamic instability because the bubble can travel much further.MarcHall:
Shoot, now I've gotten myself into a position of defending the 70# wing... which is not at all what I started out to do... I just wanted folks to think it through instead of buying a certain size wing because Andrew G. told them to.
BTW... Andrew told me to buy the 70# wing.
VTernovski
Contributor
Uncle Pug:BTW... Andrew told me to buy the 70# wing.
you really have to be careful what you say these days.. now you will have all kinds of monkeys going out and buying huge wings... let's hope they understand why rather than who.
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Uncle Pug:BTW... Andrew told me to buy the 70# wing.
... and did he happen to have one for sale at the time?
... Bob (Grateful Diver)
Yeah... I think they got in a batch of 70s by mistake.
Uncle Pug:
Using your drysuit for a bouyancy control will result in dynamic instability.
Using a wing (or a BC) that is too large will also result in an large volume and a moving bubble of gas resulting in dynamic instability.
The wing needs to be properly sized to create a balanced system appropriate for the dive. If one size fit all needs there would be no reason for a manufacturer (such as Halcyon) to produce a range of sizes (currently 40,55 & 70 lbs in doubles wings). Instead we would just all dive a 70lb (or larger) wing.
Marc Hall
www.enjoythedive.com
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