Another 18 or 30 question...

[molamola]

One of the reasons I joined this board is to ask this question ... you all seem like civil folks here . Anyway, I have read through a variety of threads here about sizing wings and I am not sure I am thinking of this correctly. I recently returned from a dive trip that gave me some things to think about in terms of wing sizing.

History


Prior to the trip I did a pool check in my 2mm wetsuit with an AL80. I needed six pounds of weight to be neutral according to the PADI approach. At our dive destination in Mexico I did a check before our first dive and needed 14 pounds with an AL80. Was probably a bit heavy, but it worked ok. During one of my last dives with this setup, my bc bladder failed and would not inflate, but I had no trouble swimming my gear to the surface and maintaining a safety stop.

I then did some dives with steel 120’s using a DiveRite Transpac. Started with four pounds on weight belt the first dive, took all that off in the middle of the dive and things were fine at the safety stop and the surface. The second dive with the steel/Transpac setup was with no weights. I had some problems staying down at the safety stop. For the remaining dives I used four pounds on a weight belt and felt as if I could cut that in half and still maintain the safety stop with no problems.

I am replacing my back inflate bc with a BPW and I am sizing the wing for warm water tropical dives with the 2mm wetsuit. I estimate the weight of the plate and harness to be 5-6 pounds (plate is 3.5 pounds). My regs are about 2 to 2.5 pounds. Other stuff is probably another pound or two (lights, etc…). If using an AL80, my understanding is that it is about 1.5 pounds negative at the start of a dive and maybe three ½ pounds positive at the end?

To float my gear at the surface, it seems I ad the weight of the rig ( including tank) which would be (plate and harness -6, stuff -2, regs, -2.5, and tank -1.5) about 12 pounds negative buoyancy. So an eighteen pound wing should work to float the rig with AL80s but probably not the steel 120s.

Using Al80s, if I want to float the rig and myself at the start of the dive, then I understand I would add about -10 pounds for my head. So that would mean about -22 pounds and I guess my wetsuit is maybe 6 to 8 or so pounds positive?? Negative buoyancy (22) plus the positive buoyancy (6-8) puts me near the limit of an 18 pound wing. (14-16 pounds total positive). This would not work to keep me and the rig afloat with steel tanks that are more negatively buoyant.

Is the 18 pound wing enough for Al80 diving in warm water with a 2mm wetsuit? Any friendly suggestions about how to sort this out?

[navyhmc]

If you needed 6 lbs to get neutral in fresh water that would be about 8-9 lbs in salt without gear. so no matter what, that 6-9 lbs doesn't need to be considered in the size of your wing.

But to answer your posted question: Yes, I do think an 18# wing is enough for an AL80 and 2mm wetsuit in warm water. With a 120, I personally lean towards the 30# wing, but that's me in cold fresh water.

[DevilDiver]

I have dove an 18lb wing with an aluminium plate for over a year (I have a 30lb as well) with about 35-40 salt water and around 40 fresh water dives on it.
I run about 185 (OK maybe 190) at 5'10" and with a 3/2 full in fresh water I need 4-6lb, same set up salt water I use 8-10lb. Now I need to say I dive a little heavy because I carry a camera set-up so when I want to stay put I like a little more weight.

Point is the 18lb wing is fine for warm water, in fact I have not dove the 30lb or the old Brigade since I got it.

[Tassie Diver]

I've used the Dive Rite Trek Wing (40lb lift) with twin 12L Steels and a stage tank and it floats on the surface no problems.

If you're diving steel twins, I'd be inclined towards the 30lb lift option if you want to be able to guarantee your gear will float on the surface (without you attached).

Of course, if you have access to both wings, the easiest way is to try it...

[awap]

If you are planning on using steel tanks in warm water with only light neoprene, you need to go with a lighter BP. Your wing needs to handle neoprene compression at depth, tank gas change and any amount you are overweighted. The difference in buoyancy between an AL 80 and a steel 120 is in the range of 7 to 14 pounds. If you used a more modern ST120, then you were overwighted using 14 with an Al 80.

The 18# wing should work for what you describe with a light BP and a steel tank. When you use the Al80, just add some weight on the cam bands to compensate for the tank change.

OTOH, if you ever move to cooler waters and heavy wetsuits with larger tanks, the 18# wing may not work so well. My solution was to get both.

[TN Traveler]

With a 3 mm wetsuit, an oxycheq ultralite plate, AL80 and 18# wing I use 12-14# in salt water and it floats me fine at both the beginning and end of the dive. If I use my SS Freedom Plate - I use 8-10 lbs. If diving steel tanks - I just remove 5-6#. Your results could vary a pound or two depending upon the fins you use.

PS - 6'1" - 225#

[molamola]

Originally Posted by TN Traveler

With a 3 mm wetsuit, an oxycheq ultralite plate, AL80 and 18# wing I use 12-14# in salt water and it floats me fine at both the beginning and end of the dive. If I use my SS Freedom Plate - I use 8-10 lbs. If diving steel tanks - I just remove 5-6#. Your results could vary a pound or two depending upon the fins you use.

PS - 6'1" - 225#

All of these replies are helpful and indicate that an AL80 or even AL100 will work with an 18# wing. I found the "wing lift calculator" on another board and used that to estimate -- since I don't know some values -- what size wing and weight is close enough. Using that calculator, here are a couple of outcomes using an AL80 and Al100. I made some rough estimates of the weights of plate, harness, regulator, lights, and other stuff as well as buoyancy of the 2mm suit.

Al80

Head weight -10 Tank full -1.4 Tank empty 3.4 Suit 6 BP&Harness -6 regs/Light -3 Doubles? n0 Integrated?n 0
Need lift: 14.8# Need lead: -0.4#

AL100
Head weight -10 Tank full -4.3 Tank empty 1.9 Suit 6 BP -6 Light -3 Doubles? 0 Integrated? 0
Need lift: 17.3# Need lead: 0#

The estimate of wetsuit buoyancy may be low, but I can measure that in a few days when I have access to a pool. But, it seems these numbers do not match with the experience indicated in the other posts. Unless I am interpreting this incorrectly, the 18 pound wing is mostly ok, but in an emergency situation at the start of a dive, there might be some added risk?

My body type is not that different than TN Traveler: I am 5-11, 205 and I workout, but I do have some stomach fat.

Anyway, this helps and I appreciate your input.
MM

ps here is another outcome for an Al100 assuming 12 pounds buoyancy for a 3mm suit.
Head weight -10 Tank full -4.3 Tank empty 0 Suit 12 BP -6 Light -3 Doubles? 0 Integrated? 0
Need lift: 14.3# Need lead: -3#

[IndyDiver]

You really don't need to depend on the estimators so much.

You already know how much weight you need to be neutral with an empty BCD at the end of the dive in your current gear - 6 lbs in Fresh water exactly. You used 14 lbs in salt water and thought that felt a little heavy, so it might be closer to 12 in saltwater. In fact, 12-14 lbs is what would be expected from doing the math based on your total weight and the fact that saltwater is 2.5% denser than fresh water. So lets say 13 lbs of lead is correct in saltwater with your current rig.

Most conventional BC's are 1-2 lbs positive in saltwater. A BP/W with an Aluminum plate will be 5-6 lbs negative. So your worst case scenario is that the new rig will be 8 lbs more negative than your your current rig, if you keep everything the same except for the BCD - BP/W switch. OK, so in the new rig you are neutrally buoyant at the end of your dive with 4-5 lbs of lead on your weight belt.

At the start of the dive you are 5 lbs more negatively buoyant due to the weight of the air in the tank. But hey, you have a 4-5 lb weight belt you can ditch. So, with no weights, you are now back to neutrally buoyant and floating with the top of your head just out of the water at the start of the dive with a full tank and an empty wing. You only need 10 lbs of additional lift to get your head out of the water and your wing can supply 18. You are all set. It doesn't matter what the internet buoyancy calculator says, those are the real numbers based on the weight you have already dived with.

So, I think an 18# wing will definately work with the gear and environment you have outlined.

But I think you really need to ask why is it important to you to get a 18# wing instead of a 30# wing. (or is it?). If you dive in fresh water, the wing will be marginal because you will need 6-7 lbs more lift. If you want to dive deeper/longer and use a steel tank, the wing will be marginal. If you want to dive in a 7mm wetsuit, the wing will be marginal. If you want to dive a steel tank in fresh water, or a steel tank with a 7mm wetsuit, the wing will be a non-starter. A 30# is really not much bigger, and it only weighs about 1 lb more for travel.

Conclusion - The 18# will work, but just make sure you will always be a warm water ocean diver in an AL80 before you spend $200+ on it instead of a 30# one.

[molamola]

Indy,
Thanks for the thoughtful and concise reply! A couple of points ... I don't have any plans to dive cold water. Warm water (+75-85) is what is in my diving future and there are no plans to do doubles or side mounts or even steel tanks unless that is the standard tank for the dive op. I can see diving with an AL100 so I can keep up with the air consumption of my wife/dive partner. The wing calculator makes it seem a little close to use the 18 pound wing, but the experience and advice of others suggests it is not. I would prefer the 18 pound wing because it may be smaller, easier to pack, more streamlined, etc.... One of the reasons to move to the plate and wing is that I just like less on my while diving, so anywhere I can cut the bulk and attend to potential emergency situations, then that will work for me. That is the motivation for the 18 pound wing, but then I may not understand the difference between that and the Mark V 30 as far as streamlined issues.

I appreciate the thoughtful and helpful replies.

MM

[IndyDiver]

I dive steel tanks in cold fresh water, so I have an Oxycheq Mach V 40#. It is probably the most streamlined wing you can get. It is definately smaller looking on a backplate than my son's 32# Edge wing.

The 30# Mach V is a SMALL wing, and the 18# Mach V is a TINY wing.

The other thing to consider is what are the emergency contingencies you want to be able to deal with the wing. I don't like to dive without a lot of redundancy. An 18# wing with an AL100 only gives you a few lbs of safety reserve. What happens if your wife/buddy has a wing failure? Can they swim their rig up to the surface, or are they going to be dependent on your wing to help get them up.

One of the things that went into my choice of the 40# is that, if my son's wing fails, I can grab the valve on his tank and swim both of us to the surface with my wing.