Dive Rite Travel Wing

[scaldwell]

Hello,
I wonder if anyone could help me here? With a travel wing, what are the practical upper limits for one to use it safely- e.g. with a semidry suit in relatively cold water (Tobago in January) with singles? Or should I look to get a bigger wing?

Thanks a lot,
Stephen

 

[cool_hardware52]

Hello,
I wonder if anyone could help me here? With a travel wing, what are the practical upper limits for one to use it safely- e.g. with a semidry suit in relatively cold water (Tobago in January) with singles? Or should I look to get a bigger wing?

Thanks a lot,
Stephen

Stephen,

Wing capacity requirements can be calculated.

A BC or wing must be able to do two things:

1. Float your rig at the surface without you in it. Just add up the weight of your tank, reg, Backplate etc. Even with a large steel tank ~10 lbs neg, a 6 lb BP and a 2-4 lb reg, seldom is more than 20lbs needed to float the rig.

2. The second thing your BC or buoyancy Compensator needs to be able to do is compensate for the maximum loss of buoyancy from the compression of your exposure suit. Even very large, thick neoprene suits will be less than 25lbs buoyant, and neoprene will remain somewhat buoyant down to ~165 fsw, well deeper than you should be going on a single tank. If your suit is say 20lbs buoyant at the surface and remains 10 lbs buoyant at your max depth then you would have inflated your wing with enough air to provide 10lbs lift.

Take your ex suit, roll it up and see how much weight is needed to sink it. This is the max lift your suit can loose.



All of the above assumes that you are correctly weighted at the surface with no air in your BC, and that you are using a wetsuit.

If you are using a drysuit, then you need to consider the maxium loss of buoyancy that might result from a suit flood. If you add weight when diving dry vs wet, then you would need to consider this additional weight in your calc's of necessary lift.

I hope this more general answer will help.


Regards,




Tobin

 

[scaldwell]

Thanks!

 

[jonnythan]

2. The second thing your BC or buoyancy Compensator needs to be able to do is compensate for the maximum loss of buoyancy from the compression of your exposure suit. Even very large, thick neoprene suits will be less than 25lbs buoyant, and neoprene will remain somewhat buoyant down to ~165 fsw, well deeper than you should be going on a single tank. If your suit is say 20lbs buoyant at the surface and remains 10 lbs buoyant at your max depth then you would have inflated your wing with enough air to provide 10lbs lift.

Take your ex suit, roll it up and see how much weight is needed to sink it. This is the max lift your suit can loose.

You missed "plus the weight of the air in your tank." If the suit loses 10 pounds by 100 feet and you have 6 pounds of gas in an Al80, you'll need 16 pounds of lift if you're correctly weighted. Add one pound of lift for every pound you're overweighted

 

[cool_hardware52]

You missed "plus the weight of the air in your tank." If the suit loses 10 pounds by 100 feet and you have 6 pounds of gas in an Al80, you'll need 16 pounds of lift if you're correctly weighted. Add one pound of lift for every pound you're overweighted

Jonnythan,

I think we are in agreement, even if it might not appear so. My assumptions are based on a diver being neutral at the surface with a full tank, and zero air in the BC.

The tank will never be heavier, it will only get lighter. This can't possibly add to the required lift.

On the other hand if a "500 psi at 15ft & no gas in the wing" buoyancy check determines that you can't hold the stop, then you need more weight, and more weight increases the necessary wing capacity.

My experience has been, in colder water (high 50's low 60's) that the typical wetsuit will loose enough buoyancy at 15ft that to offset the weight of the gas in the tank from full to ~500 psi.

I can see where warm water could result in so little neoprene being worn that holding the stop with a near empty tank might be problematic.

The original poster was asking about cold water.

If I'm still misssing something let me know, I never mind another pair of eyes checking my work


Regards,




Tobin

 

[jonnythan]

If you're neutral at the surface with a full tank and no air in the BC, you're underweighted by the air in your tank.... and you will be that amount positive with an empty tank at the end of the dive..

 

[ShakaZulu]

If you're neutral at the surface with a full tank and no air in the BC, you're underweighted by the air in your tank.... and you will be that amount positive with an empty tank at the end of the dive..

Nah, I don't believe that........... so that's why they always say add 5lbs if you are neutral at the surface?

 

[cool_hardware52]

If you're neutral at the surface with a full tank and no air in the BC, you're underweighted by the air in your tank.... and you will be that amount positive with an empty tank at the end of the dive..

Absolutely, at the surface, but not at 15-20 ft. in a wetsuit.

It may be wetsuit vs dry that drives our differing opinions. My 7mm looses a ton of buoyancy in the first 15-20 ft. If I'm weighted for a steel tank and borrow an AL80, I usually just swim it down to about 10 ft or so and I'm good. I'm a pretty big fella, so there is a few square meters of 7 mm to compress.

A drysuit on the other hand should in theory change little in buoyancy with depth if the same interanl volume is maintained. In this case I can see the problem as you describe it.


Regards,



Tobin