Questions about doubles

[WestCoastDivr]

Right now I only have a single rig system but I am hopefully going to begin taking tech courses towards the end of the year where I will need a doubles setup with isolator manifold as well as deco bottles. I am looking into purchasing my first steel tank which will be what I dive with until then, but I'm not sure If I should buy two since I plan on using it in a dual setup later on. Would it be worth it to buy two or should I only buy one and buy 1 or 2 more tanks later? Also, is it ok to dive doubles with two tanks that aren't the exact same but have similar buoyancy characteristics or do they have to be the exact same tanks?

Thanks

 

[NAM001]

If you are going to get doubles buy then both at the same time so the hydro's are in sync. Next the steel vs al issue. Are you going to need steel for the weight qualities If you are going to use them in fresh water the general guidence is al for fresh and steel for salt. You will have to figure the total neg buiyancy to decide this. The total positive lift of the al tanks are usually off set by manifold and the bp/w. lp steels when over filled can be quite heavy. lp-85's at 31# are light compared to say teh lp104's and 108's definately lighter than lp120's. Also general guidance says that if you are going to use duoubles then wear a dry suit for backup buoyancy. Ive blown a wing with a wet suit on and its not pretty. If diving a dry suit then steel is almost a must to counter the suit. You are probably much younger than me, pumpd lp 85's are about all i can handle doubled. lp104's are 46# each. and a oms 108 is 41#. Many are diving hp 100's and they seem to be a popular tank at just 33# each. Are you looking to do penitration dives or open water? BTW my double 85's with bp/w and regs are about -28 to -30+ buoyancy when full.

 

[WestCoastDivr]

So far, from what I've read, I was planning on adapting my rig into a double hp steel 100 with a dry suit mostly for salt, cold water diving when I begin tech. I have a DSS backplate so when I do switch do doubles I will need a compatible bolt system as well as a new wing for doubles with more lift. I'm not sure if I can afford two tanks currently, so I suppose I'm worried that I may buy a single tank and then not be able to find a twin for a reasonable price so I will be forced to buy two more tanks.

 

[scubastingray]

Hey If you need a new wing I couldn't help you more than recommending you check out dive addicts hollis wing blowout. I'm in no way affiliated, but i got a brand new 60lb donut which has worked great for my doubles for $100. Check out their specials and consider grabbing one while they're still on sale. http://store.diveaddicts.com/technical-diving-clearance


I'd agree that buying the tanks at the same is a good idea, although having to hydro a few months early isn't the end of the world (and I'd rather do that than come back a month later).

If you are looking at a doubles setup, make sure you get a valve/iso bar set that can be used independently, although I don't have much experience with it I'm not sure if they all can.

Ultimately if you want to go doubles, it's much nicer to have a set than to need to break them down and put them together every time you want to dive. If you want a single tank now, buy that. Trying to get rid of your single tank and only having doubles down the line would be problematic unless you only want to dive doubles.

 

[Jerry_]

As you are going to buy both your "normal/single" now and expect to buy your doubles rig in a not so far future, here are my two cents contribution.

Upgrading from a single tank to a double is possible but not very interesting, because the only cash benefit is with the cost of the tank. However, buying a double rig, involves - extra to the costs for tank - the manifold and a different (type of) wing, provided your single tank purchase was ok for upgrading (i.e. You are likely to make a number of compromises when buying your single tank configuration in view of upgrading it to a doubles setup).

My recommendation would be to:
- either go for a single tank setup, without any other compromise, and do that adequat to your current need and experience.
- either already buy a correct double setup and take classes to use them straight away, as you can also dive doubles on a non-tech dive.

Whatever you are going to do, it will cost some bucks. Diving tech will need you to buy number of other stuff if you want to make it seriously.

With the two proposals above, my choice - in your situation - would be to buy a correct single tank setup. If you get to the tech level you should evaluate how you want to progress:
- keep both a single tank setup and a new doubles rig,
or
- sell your single tank and reinvest the money in a double tank rig.

 

[NAM001]

I can tell you are definately new to doubles. ALL back plates have the same bolt pattern. Holes on 11 inch centers. Going into doubles is not cheap. You dont have corners to cut in the set up. I am going to guess with undies your dry suit will give you 30-40# lift. Given that fresh or salt you will need steel tanks.
Add about 18 lbs for a teeel plate rig to hte tank buoyancy's. so if your tank is -10 full then doubles makes -20, - 18 and that gives you about -38 for your rig. That would pretty well ballance your dry suit out. For that ballance you would need a real small wing like an 18 if they make one, but if your suit floods you will need another 30-40 so the wing is now a 40-50# wing. If you dive wet then you need the 40-50# for sure. once again are you doing penitration dives or not? If you are doing cave then the lp's may be a better fit for your need. steel 100 is a popular tank and what i have heard it trims well, but full is near 3500#. With that you would surely have to go to din regs.

So far, from what I've read, I was planning on adapting my rig into a double hp steel 100 with a dry suit mostly for salt, cold water diving when I begin tech. I have a DSS backplate so when I do switch do doubles I will need a compatible bolt system as well as a new wing for doubles with more lift. I'm not sure if I can afford two tanks currently, so I suppose I'm worried that I may buy a single tank and then not be able to find a twin for a reasonable price so I will be forced to buy two more tanks.

 

[TSandM]

Buy a single tank you can use now, and buy a set of doubles when you need them. Used doubles are not hard to find around here.

 

[kwinter]

Buy a single tank you can use now, and buy a set of doubles when you need them. Used doubles are not hard to find around here.

+1
Buy a comfortable harness and plate you like. If the plate has slots for cam straps, you're good to go. If not, get a STA. Get a wing that can handle both singles and doubles. Now you're all set for diving your single until you decide to get doubles. Then buy a set with bands and isolation manifold and that's all you'll need. Assuming you have 2 complete DIN regs.


Please pardon any typos. Sent from my iPhone using Tapatalk

 

[neonstingray]

I'm using a DSS plate with double HP100's also. I'd highly recommend against trying to piece together doubles one tank at a time. Just keep an eye out for people selling a used set. Unless you're a big strong guy, I'd stick with either LP85's or HP100's. Also note that the Faber makes two 100cf steel tanks. You'd want the FX100, which is Faber's equivalent to a Worthington HP100. The Faber M100 is a boat anchor and too heavy to be doubled.

 

[WestCoastDivr]

Thanks for all the advice everyone. Due to the cost, I'll most likely just stick to a single tank for now. I checked the LA craigslist page (which is where I'll be moving towards the end of the year) and there were quite a few steel tank and steel doubles for sale so I can buy a used set if I want to upgrade once I'm down there.