I called Halcyon on the topic last week. The outside profile of the wings is similar so they said there would not be a noticable difference in drag in the water...the 40# is just a little wider For cold climates where divers need more weight to compensate for thicker suits, they recommended the 40#. The other piece that has not been mentioned is that for larger tanks, they preferred the 40# wing as it "wrapped" better around the tank and dove better. They would dive the 40# wing on larger tanks (and clearly they have a choice). I found that interesting as a different vendor also recommended their larger wing as it dove better than the smaller one, even though on paper the smaller one has sufficient lift to get you to the surface. So there is more than just math at work. Hope that helps
Choosing 30 or 40 Halcyon eclipse
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For a bit of perspective, my buddies and I dive steel doubles in cold water and all use wings with <= 40lb lift.
Roughly speaking,
ss backplate = 6lb
trim weights = ?lb
6 pound attachment to the tank = 6lb
What kind of tank? With steel, probably 7-10lb
Regs/harness etc. = 2lb
Depending on your trim weights and any other gear you have, 30lb is probably OK but it can get close pretty fast. What kind of tanks, how much trim weight and what exposure protection will you be using? All of these will affect the end result.
Roughly speaking,
ss backplate = 6lb
trim weights = ?lb
6 pound attachment to the tank = 6lb
What kind of tank? With steel, probably 7-10lb
Regs/harness etc. = 2lb
Depending on your trim weights and any other gear you have, 30lb is probably OK but it can get close pretty fast. What kind of tanks, how much trim weight and what exposure protection will you be using? All of these will affect the end result.
FishOutUvH2O
Contributor
The largest tank I've used with my 30# Eclipse is an AL100 and it went up the sides of the tank about half way. So what type of tanks are they referring to and how much wrapping are they talking about, that would make the 40# dive better? This is the first time I've heard this, so it's got my curiosity peaked.
well i just bought a 30 wing from another board member. Ill be doing my diving in the virgin islands so i only have a hammer vest for protection. also it has a ss backplate (6lbs) and a 6lb tank adapter. On previous dives ive only needed a 12 lb weight belt for weight so will this be enough weight for the type of diving i will be doing?
ASSUMING you were properly weighted at 12lb before, this should be right. You may be able to get away with 2-3lb less if you've been diving a jacket BC before (since the BC is positively buoyant and requires a couple of extra pounds to sink it).
FWIW, if you're not diving with a wetsuit, it does seem a bit overweighted to me. This exact configuration (6lb SSBP + 6lb STA) is what I use for diving tropical waters, and I typically wear either a 3mm farmer john, or a shorty over a 3mm fullsuit, with an AL80 tank. And I could take off a couple of pounds from that, too. If you're not wearing a wetsuit, the only positive buoyancy your gear needs to displace is your body, 4lb from an empty AL80 and maybe your fins.
scubafanatic
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umm, not sure I waste my valuable/limited luggage weight limits on a 6 lbs adapter......surely you can buy a more travel-friendly (lighter) adapter, at least for air travel ?
My STA is convertible - there's a 6lb block of coated lead that can be removed from the channel, and the remaining STA with cambands is maybe 2lb negative. IMO, along with a 5-6lb stainless steel backplate, that's probably all a typical person would need for no-wetsuit warm-water diving. I'm sure someone will let me know if I'm missing anything:
Human: anywhere +/- 3lb, probably slightly positive
AL80: ~2lb negative at start of dive, 4lb positive at end of dive
SSBP/unweighted STA: ~7-8lb negative with an unweighted STA
Regs: ~2lb negative
Shirt/trunks: let's call it neutral, it's definitely not buoyant exposure protection.
So without a wetsuit, you're looking to displace about 7lb of positive buoyancy at the end of your dive. Your SSBP + STA does about that by itself and you get another couple of pounds depending on your regs. You can control about 6lb using lung volume alone, so even if you're a few pounds overweighted here, you can start to ascend just by taking a deep breath.
Anything additional lift capacity you have (whatever your wing is weighted for) is just icing on the cake in this scenario, and some people will simply dive a similar config without a wing (not that I'm recommending that).
Note that at the BEGINNING of the dive, the 6lb worth of air in the tank makes you about 8 to 10lb NEGATIVE net, so in the event of a catastrophic wing failure, you'll need to be able to swim this up to the surface and stay there for a while (most people can) while you get out of your gear to establish positive buoyancy.
Shark Bait!
Contributor
Not sure if this will help any, but i think if your gonna use a BP/W in tropical water, i think a 40# wing is a little excessive, and even a 30# wing is a little overkill. As for me i use a kydex BP with A 20# wing, HP100 steel tank, 3mm full suit and no more then 0-2# or weight on my waist. 2# if im doing shallow shore dives as i feel the added weight helps keep me down a little more easier in that 10-20ft depth range. I started with 6#s and have weined myself down the more i dive. Im 5'9 185ish #s. My 20# wing has no problem floating my rig by itself, i have no issues swimming my rig to the surface with no air in the wing, and i have no issues holding a 15ft safety stop.
This is just my experience as i am by far no expert, but i am interested in understanding why people in tropical water wearing a BP/W and a 3mm would wear more then 6# of addition weight?
This is just my experience as i am by far no expert, but i am interested in understanding why people in tropical water wearing a BP/W and a 3mm would wear more then 6# of addition weight?
FishOutUvH2O
Contributor
The short answers:
Maybe they're overweighted.
Maybe they did a buoyancy check and with their rig and particular 3mm wetsuit they required more than 6lbs of additional ballast.
There are many different body types out there. Some are more "floaty" than others. Not every 3mm has the same buoyancy. And people have different rig set-ups (BP material, accessories, etc.) The point isn't how many pounds/kilos a person is using. The point is that whatever they are using is not to much and not to little. That's why a buoyancy check, however you choose to do it (PADI, or some other way) is a good idea.
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