Question Which double tank size + which type of wing?

[Imla]

Coming from one who has used all but the 10s in Norway.

D7 300 bars. I love them. Small, relatively light, very nicely weightdistributed, but shorter than 12s, so mos people find that they cannot rest them on a bench. Compared to a 15l they will have a smaller and more stable profile.

D8,5 VERY tall bottles. Personally, I have a short torso and these tend to make me very top heavy. I sold mine, and bought D12s in stead. If you are a very tall guy 180cm+ these might work perfectly fine.
They are a bit on the snippy side for technical dives, but work well for recreational. Too small for 2 dives usually.

D10s. Useless. Trim of these are horrible, There is a reason they are not used.

D12 232s. Allround workhorse. Trims well. Works very nice with drysuit. Nice length. Works well with technical dives. Can get 2 dives on a fill. Cons: a bit on the heavy side, and usually you'll dive slightly overweighted on every first dive of a fill.

I have one set of D12s for technical dives or sidemount should the need want arise. (and a rebreather)
And I use a D7 for recreational dives.

If you have the option to try the D7s and the D8,5s, try both and check how they feel. Balance point is slightly different and different bodies might like different bottles.
D12s, most people love. Just keep in mind the balancediffernce with concave/convex bottoms.

 

[rduquesnoy]

If your goal in the end is doing more technical diving then my suggestion would be to start diving with the setup you eventually intend to use. That would mean buying a D12. Handling the weight shouldn’t be too much a problem, even I can manage fine most of the time and I am just a 1.60m tall girl.

With the doubles I use a 40lbs (18 kg lift) wing and a RVS backplate. During the winter, (with thick undergarments and a heated vest) I use an additional 5 kg of (tail)weight in fresh water. For salt water I just add another 2 kg. During the summer 3 kg is sufficient. My partner always uses the same amount of weight, maybe I could lose another kg but my current setup works for me.

I can’t tell how all this would compare to a compressed neoprene drysuit (I use a trilam) but when I switched to doubles I got rid of my compressed neoprene drysuit. It was impossible to reach my valves. Don’t know how flexible your suit is but this is surely something to take into consideration. Besides that the trilam gives me more flexibility in choosing the appropriate undergarments for the season.

 

[inquis]

So I'm left with 1,200 liters?
(14*260)/0.33
Or if i had 300bar i have 1,400 liters left.

Shouldn't that be enough to rise to the surface?

The bigger concern is a failure at the end of the dive.

 

[pisauron]

The bigger concern is a failure at the end of the dive.

Failure at the end can happen with 12s also. So i Don't find tank size relevant.

 

[Rich1280]

Afternoon. As others have said, the D12s are ubiquitous because they just work best for most things. Shallow dives, 2-3 on a fill. Deeper dives, enough gas. Deco dives, add a stage and lovely off you go. If you're particularly short in the torso a set of fabers will trim OK. If you're normal sized or tall Euro style with round or concave bottom will fit better and trim nicely. I've had D8.5s, they dived nicely, but gas matching was a problem when all your buddies are on D12s.
Get a second hand plate and wing, they're easy to get hold of and just work. Steel would suit with the compressed neo drysuit and reduce your lead requirements.
Good luck and enjoy!

 

[MrBlenny]

@DutchDiverDude I realize you expressly asked about doubles, but just curious if you have considered slinging an AL40 (5.7 liter) pony bottle? Properly configured, I don't even notice mine is there during a dive, plus I can visually confirm for leaks and easily reach the valve. It also weighs a lot less than doubles. If you need more gas than that, doubles (or in my case side-mount) are the way to go.

 

[DutchDiverDude]

Thanks for all the advice!
Last week I came across a nice and affordable 2nd hand wing, stainless steel backplate and d12 set which I decided to buy.

I'm curious how the lead requirement will change now. Assuming no other change in gear, I'm going from a normal BCD with steel single 12L to a steel backplate and steel d12 set.
Is there a 'rule of thumb' to apply here for how much lead I can drop?

I guess I'll have to properly do a weight check again, but it is nice to know where to start.

 

[Imla]

Thanks for all the advice!
Last week I came across a nice and affordable 2nd hand wing, stainless steel backplate and d12 set which I decided to buy.

I'm curious how the lead requirement will change now. Assuming no other change in gear, I'm going from a normal BCD with steel single 12L to a steel backplate and steel d12 set.
Is there a 'rule of thumb' to apply here for how much lead I can drop?

I guess I'll have to properly do a weight check again, but it is nice to know where to start.

Assuming you dive in Netherlands with a dry-suit and winter undergarments, Try a 4,5kg v-weight and 2+1kg on your left side waistband, just thread them in on (not both) of the holes, with the hole not used on the outside) If you do not have a can light, secure the weights with an extra belt buckle.

 

[DutchDiverDude]

Thanks Imla, I dive in a neoprene drysuit and only have a single set of garments. However, no cold issues in 4 degrees celcius water except for the hands .

With my current single tank, I wear 2x 4kg pockets, and a 7kg belt, in total 15kg.
Since all that changes is going from single tank BCD to double tank wing with backplate, I'm more interested in a 'relative' comparison instead of absolute numbers. Compared with the bcd, how much weight would I be realistically able to drop?
Imla, you're suggesting dropping 7.5 (or 8) kg for now?

I expect that in the near future I will switch to a trilam suit (my neoprene is old and is showing small cracks in the outer surface already, but for now I'll go with it until it dies.

 

[Alex Ouroboros]

V-weight is by far the nicest way to go however I would try and work out how much lead you will need, in fresh water I imagine you would be 0-1kg, with an extra 4kg in the sea, once you have weighted yourself I would go for the V-weight(s) they come in a variety of sizes so you can buy what you need to put where you’d like, a good tip would be to use a cam band (or 2) for your weight in the sea at this point so you can fine tune how far up or down the cylinder they are needed, once your happy with weight distribution buy the V-weights that are suitable,,, enjoy.