Doubles

[Lindan]

Hi Dan L glad to read you're still around! I am thinking of purchasing doubles also. What set up did you decide on? I'm diving Grand Marais harbor the weekend of the 13th, but wouldlike to do Wazee the following weekend.If you are interested let me know! Linda

[LKunze]

Linda, you should check out the Worthington Low Pressure 85's or the High Pressure 100's.  Both tanks are the same size but the High pressures hold an extra 15 cubic feet of air per tank.  The High Pressures also cost a lot more and for me I found the extra air did not justify the added cost.  Either way they are nice doubles.  I have a set of OMS/Faber 85's and a set of Worthington 85's and love them.  I wouldn't want anything bigger though I am not doing 300 foot trimix dives with them either.  To answer your question for DanL he is using the Worthington High Pressure 100's. Dan G is diving those as well. 

[Kirk]

Both tanks are the same size but the High pressures hold an extra 15 cubic feet of air per tank. 

The Low Pressure 85 tanks are actually a little bit longer in length, and when pumped up to the same psi, hold more gas then the High Pressure 100 tanks.  For instance at 3600 psi, doubled LP 85s give you about 232 cubic feet of gas, while at the same pressure, doubled HP 100s only give you about 209 cubic feet of gas. - Kirk

[LKunze]

Kirk, you are right. The LP85's are 24.7" long and the HP 100's are 24.0" long. 

[Dan G]

Although, if you did the same 46% overfill on the HP100s as is the case with 3600 psi in the LP85, you would have 292 cubic feet of gas, although it might be a little hard to find someone to put 5,000 psi in your tanks
Dan

[DanL]

Linda,
Try a set of doubles before buying.  I originally bought Faber 108's and they were just too heavy for me out of the water.  The HP100's are fine.
Thinking of Wazee on Sun Jan 21 - can't make Sat Jan 20.

Kirk, you fill your LP's to over 3300?

[Kirk]

Always.  These same 2640 psi tanks are actually rated in Europe to 4000 psi (which is our hydro pressure).  Here in town for my sets of doubled low pressure 104s, I usually ask for 3500 psi (which might cool down to about 3300 in the water).  Down in cave country anything less than 3600 psi is considered a bad fill.  The way I look at it, if things go bad, I want as much gas as possible to sort things out. 

Since in North Florida you pay by the cubic foot, if you show up with almost "full" tanks, it's no big deal, no money lost (though there is a minimum charge for nitrox, I don't remember exactly what it is, but if you bring a 3000 psi aluminum 80 stage bottle on a dive, and you use it, sip at least 1200 psi off of it on the way out of the cave to cover the cost).   

In the winter months down in the North Florida springs, sometimes the water temperature is warmer than the air temp, and the tank pressure actually increases when you hit the water, which is always nice (unless you got a very generous fill to 4300 psi, and are worried about those loud burst disks).

Don't excessively overfill aluminum tanks, and don't excessively overfill old steel 72s.  They weren't made for it.

I wish I was joining you tomorrow.  My drysuit hasn't gotten back from Brainard, and when it does get back, I'm heading back down to North Florida's cave country...  - Kirk 

[tcjtn0]

Oh sure , EVERYONE is diving doubles now ...  :o
Er ...
Have fun at Wazee you guys!!!
I'll be thinking about you hangin in this 72 degree water...  \

HAPPY NEW YEAR !!!

Da Beano

P.S.  I still haven't given up using my Double 50's down here but I use my Faber LP 85's most of the time.  I can even do the Grand Traverse at Peacock on them. 

[Lindan]

Wow, mention doubles and the info flies back, talk about service! Thanks guys and Jeeano for all your info. I assume you all are referring to steel? I have a concern about the Weight of the tanks. Going to doubles is going to make me too negative not including adding stages etc.  I have been diving a single95 and love the compact size and the lack of becoming too positive at the end of the dive, but could no way carry 2 of them! Yikes! So I was thinking oftrying aluminum 65/s. My sac rate is good enough that I don't need tons of extra air in my primaries, and the weight will allow me to carry the stages that I like. The driving goal is to spend more time on the Emperor and eventually dive the Kamloops. Trimix is definately in my future also and something to work for later, but right now doubles, and the redundancyand manifold options they offer is going to increase my bottom time at those depths. I'm going to try those and a set of 80's to see how it goes. Thanks again for the input and Dan L I am interested in sunday the 21st also. I'll get back to you after I get home from Grand Marais. Linda

[LKunze]

Linda, I'd definately go with the steel 85's.  They are not overly negative at all and are quite manageable out of the water as well.  The 85's are -6 lbs. full and neutral when empty.  Diving dry, steels are the way to go.  Aluminum 63's might work for a light deco dive but if you are talking trimix and the Kamloops even with an excellent SAC rate, you are going to want much bigger tanks so you have sufficient air for emergencies as well.  Keep in mind, most divers diving the Kamloops are diving twin 108's or 95's.  Aluminum 80's would do but the steel 85's would be a better choice, don't cost too much more than aluminums (approx. $199 per tank new) and don't have the positive buoyancy swing of the aluminums.  If you want sometime I'll let you try a set of my 85's out to see how you like them.