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I am looking to buy myself some tanks for a doubles set -up. Previous I have been diving mostly in Asia and have used AL 80 (11.4 LT) Tanks for my twins (I am also wear a 5 mm wetsuit) .
I am prepare to dive with a drysuit in the Pacific NW here in the near future and wanted to get my own tanks for diving near home.
I am wondering with the drysuit, should I only be looking at steel tanks, or will AL work the same with a dry suit? What are the pros and cons? Thanks for your time!
It's not clear -- are you MOVING to the PNW? If so, you'll most likely want steel tanks, because with the exposure protection we have to use, anything that decreases the amount of ballast one has to carry is a good thing.
You can certainly dive Al80 doubles with a dry suit. I dove them in the Red Sea, and I dive them in the caves in MX all the time. I don't use them in Puget Sound, because I don't want to carry the extra lead -- I use steel 85s or 100s.
Has Zombie left eye ala Marilyn Manson, but for real (Corneal Hydrops).
Join Date
Jul 2005
Location
South Santa Monica Bay/Los Angeles California, USA, Planet Earth, a blue world 71% water & third planet from a G2 yellow dwarf star, in the Milky Way Galaxy two thirds of the way out from the center on the inner edge of the Orion–Cygnus arm.
I mostly use Catalina double 11L tanks (AL80's) for drysuit diving with 200g/m2 thinsulate undergarment --here in SoCal for average water temperatures 12-16deg C. Also use 17L (LP104's) steel doubles for deep tech diving locally as well. . .
Weight ballast neeeded with the AL80's: 2.5kg steel backplate plus 5.5kg of lead (2kg weightbelt on the hips and the remaining 3.5kg ballast in a tail weight pouch & V-weight pouch). For the steel 17L doubles, I just have the steel backplate at 2.5kg and 2kg in the tail weight pouch. I weigh-in at 70kg and am 170cm tall.
In the tropics (Puerto Galera Philippines/SE Asia/Micronesia), I always use double 11L (Luxfer AL80's) for tech diving with no weight ballast other than an Aluminum 1kg backplate; exposure suit is a 1mm skin wetsuit with a 3mm hooded vest for water temperatures 28deg C and above.
"Luck is the residue of design."
Branch Rickey. "A Life is not important . . .except in the impact it has on other Lives."
Jackie Robinson. "Chance favors the prepared mind" --Louis Pasteur
It's not clear -- are you MOVING to the PNW? If so, you'll most likely want steel tanks, because with the exposure protection we have to use, anything that decreases the amount of ballast one has to carry is a good thing.
You can certainly dive Al80 doubles with a dry suit. I dove them in the Red Sea, and I dive them in the caves in MX all the time. I don't use them in Puget Sound, because I don't want to carry the extra lead -- I use steel 85s or 100s.
Yeah, I am moving over. I am from Oregon, but looking to get a place in Vancouver WA. I wanna make regualr trips up to the Seattle area for diving. I have never been diving over there, so I am trying to get it all together now, and just figure out how to set myself up. I'm still several months away from actually diving up there. I gotta get my a dry suit and learn how to dive with it also! Thanks for the help!
If you want to set up with doubles for Puget Sound, HP100s are very popular -- enough gas for dives in the 150 foot range, but still small enough not to ruin your discs. Most people who tech dive end up with multiple sets of doubles, anyway, because the ones you want to dive always have the wrong mix in them. We have LP72s, 85s, and 100s.
We have HP100's, HP119's & LP72's. We have used the 72's filled to 3000 for 200' dives and they worked just fine, but they take extra lead. My personal favorite is the HP100's.
Like most diving applications, your gear should fit the dive. You will get a lot of different views, each with its own pros and cons. Get a skilled instructor/mentor to help you. I dive wet/semi wet and prefer steel. I use 15L fabers for my doubles and love them. I only use ali for stage/deco tanks.
In the tropics (Puerto Galera Philippines/SE Asia/Micronesia), I always use double 11L (Luxfer AL80's) for tech diving with no weight ballast other than an Aluminum 1kg backplate; exposure suit is a 1mm skin wetsuit with a 3mm hooded vest for water temperatures 28deg C and above.
Just out of curiosity, how do you account for the 8.8lbs positive buoyancy of the empty tanks?
Has Zombie left eye ala Marilyn Manson, but for real (Corneal Hydrops).
Join Date
Jul 2005
Location
South Santa Monica Bay/Los Angeles California, USA, Planet Earth, a blue world 71% water & third planet from a G2 yellow dwarf star, in the Milky Way Galaxy two thirds of the way out from the center on the inner edge of the Orion–Cygnus arm.
Just out of curiosity, how do you account for the 8.8lbs positive buoyancy of the empty tanks?
Simply my own body's buoyancy, and breathing control in addition to the 1kg backplate to counter the empty tanks!
An adult's lungs can hold around 5 litres of air (10% more than an Imperial gallon or about 30% more than an American gallon) providing 5 kg of buoyancy (about 11 lbs.) So the amount of air in the lungs makes a lot of difference - the difference between floating and sinking in the case of an average adult male. Personal buoyancy is always measured with the lungs full of air.
I've easily held a 6m Oxygen deco stop with as little as 30bar left in backgas, and a depleted 5.5L Eanx50 deco bottle --however my wing at that point is completely deflated and no longer providing any lift. Potentially though, there could be difficulty holding a 6m stop and/or a slow controlled 1m/min ascent in strong swirling currents and rough surface conditions. . .
"Luck is the residue of design."
Branch Rickey. "A Life is not important . . .except in the impact it has on other Lives."
Jackie Robinson. "Chance favors the prepared mind" --Louis Pasteur
Just out of curiosity, how do you account for the 8.8lbs positive buoyancy of the empty tanks?
Also, AL80 doubles are about as bouyant as a single AL80 due to the bands, manifold, and extra reg stuff on them. I don't change my weighting between single and doubled AL80s.
There is only so much that can be dumbed down, but you can never replace the need for skill and competence to get yourself out of an emergency. - battles2a5
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Originally Posted by TSandM
