Evolve 40 or 60 with doubles?

[Jeepman3sk]

Hi there,

I am between the Halcyon evolve 40 and 60 for a pair of 100s. Which would you recommend? Also I would like the possibility to go up to 120s in the future without having to purchase a new wing. Right now I am diving Halcyon but with singles. I would be diving mainly dry when I use the doubles.

Thanks!

 

[PerroneFord]

40 is fine for AL80 sized tanks. Larger Iwould use the 60s.

 

[masterof0]

if you do a search on the user cool_hardware52, he addresses this question very well by explaining the steps on how to determine your lift requirements. Based on the limited information you are providing, I would say you will end up the 60, but there are things that are critical to know when making that determination such as your current ballast requirements with the suit and undergarments on a worse case scenario.

One things to keep in mind that I did not take into account initially when I was asking a similiar question is that if you think about doubles with a general assumption that you will be doing some sort of technical diving, it is important to keep in mind that, generally speaking, ditching weight no longer becomes an option as you will not want to do a direct ascent to the surface. This is important to keep in the back of your mind because, as a recreational diver, this is an option that is available to you so if you do have a catastrophic failure, to your wing and or suit, you can use this to help assist with your ascent to the surface.

 

[b1gcountry]

I haven't had much luck in getting the 40lb wings to float my steel doubles.

Full, even the HP100s have 16 lbs of nitrox/air in them. The tanks, manifold and bands will be 8-10lbs, and a steel BP with all your hardware/can light will be 10lbs or more. That leaves very little room to spare. If you figure the tanks will pinch the wing a little when fully inflated, you probably won't get more than 35# of lift out of the wing anyway, so you might just opt for the larger wing.

Tom

 

[TSandM]

That's funny -- I haven't had any problems floating my doubles with my 40 lb Deep Outdoors wing (that's with LP72s, LP85s, and HP100s). I suppose, if I were diving bigger steels with cave fills, things might be different.

 

[Gombessa]

Tobin's post here does a good job explaining how to calculate the lift needed for a doubles wing:
http://www.scubaboard.com/forums/4309784-post21.html

Using this as a baseline, I threw my own kit up and came out with the following numbers (relevant for cold water with HP100s/LP80s).

You are dealing with a bit more gas weight in 120s, but I think the main question is what kind of exposure protection you'll be using.

FWIW, a couple of my buddies are diving 38lb wings with double steel LP80s and 400G insulation, and have had no trouble floating them (one had a total wing failure recently and just surface swam back without ditching or overinflating his suit). If a smaller wing works for you, I say go for it. It's pretty noticeable and annoying to have a big floppy wing that has way more lift than you need.

 

[cool_hardware52]

You are dealing with a bit more gas weight in 120s, but I think the main question is what kind of exposure protection you'll be using.

Yup.

Tobin

 

[Jeepman3sk]

Wow! Thank you everyone for your responses. I will run all of the calculations to figure this out. I haven't started tech diving yet. But I was hoping to start training when I get back from living in Europe. Once again thanks everyone!

 

[cool_hardware52]

Wow! Thank you everyone for your responses. I will run all of the calculations to figure this out. I haven't started tech diving yet. But I was hoping to start training when I get back from living in Europe. Once again thanks everyone!

The buoyancy characteristics of back plates, regs, tanks, can lights etc. are pretty easy to estimate with enough accuracy for these purposes.

OTOH......

The **Key** piece of the puzzle is the buoyancy of your drysuit with minimum gas in it.

Virtually no diver can provide me this information when I ask for it.

The buoyancy of your suit is not:

How much lead you used last July in Bonaire with a 3mm wetsuit.

How much lead you used when you used some other drysuit with some other undergarment with ah, you know, the "standard" rental tank and an unknown BC.

There is no "Universal Cross Reference" for undies and suits, so make and model won't help much either.

---------------------------------------

To determine the buoyancy of your drysuit you need your undies, drysuit, a big bag of lead and some neck deep water.

Put on the suit & Undies and get into the water with plenty of lead. Vent the suit as much as you can.

Remove lead from the bag until you just barely sink when you pick up your feet.

Weigh the bag of lead.

If you do this test in fresh water you need to add 1 lbs of ballast for every 40 lbs of diver if you plan to dive in salt water.

Tobin

 

[Jeepman3sk]

One other question to ask. What is the typical tank you guys dive. I'm just starting to get into the tech diving and I can get a good deal so figure I would take the steps into properly getting the gear.