18 lbs Vs. 26 lbs??????

[SeaFlea]

Greetings all, I need some of your feedback please.

I'm trying to decide between a 18lb Oxychec wing and a 26lb Hollis wing. Granted I do agree less is more from the airline weight allowance and the benefits of streamlined gear underwater but.........

follow this, BP w/ STA = -9lbs,
weights = -4lbs
regulator = -3lbs (approx)
fins / mask / computer = not sure

just counting these my wing needs to counter at least 16lbs of negative buoyancy. Seems to me I'm getting close to the 18lb wings limit. What other factors am I not considering?

Both wings cost about the same and both are very well made, no big difference there. I just am not sure if 18 will give me enough safety margin.

Please tell me if I'm overlooking something.

Thx, Good Dives, SeaFlea

 

[scubafanatic]

Generally there seems to be an ongoing contest here on SB about who has the tinyist wing, I tend to not mind a wing with somewhat more than the theorietical minimum calculated lift requirements, to accomodate more varied dive conditions and Murphy's Law. Moreover, your rig needs to be able to float by itself on the surface (without the added bouyancy of your wetsuit) if you ever have to take your rig off at the surface.

 

[hg frogman]

SeaFlea,

I fully agree with Scubafanatic.

By the way, I am afraid you forgot the negative buoyancy of your tank full of air (about 2 or 3 lbs with an Al80, more with a steel tank).

I own both 18 and 30 lbs wings. I use them with a SS backplate, full wetsuit (3 to 7 mm), aluminum or steel tank, and usually no or little lead. I feel no difference between these wings underwater : both work fine, and I don't feel more drag with the 30 lbs, even when there is current. The 18 lbs is shorter and packs smaller but it doesn't give me the same amount of lift at the surface, and if the sea is choppy my 30 lbs is much more comfortable (= keeps my head above the water).

 

[rstofer]

Please tell me if I'm overlooking something.

There's a 'Sticky' at the top of this forum that will ultimately allow you to download an Excel spreadsheet where you can work through all this stuff. There are 6 points in time that you need to evaluate before you can say that the wing buoyancy is adequate.

For the cold water diver, the maximum buoyancy requirement for a rec dive using a single tank (probably steel) tends to be at the beginning of a deep dive where the tank is still full. The wetsuit has lost at least half of its buoyancy at depth and the tank is still highly negative. In this situation, a 30# wing will be close to the limit.

Give the spreadsheet a try.

Richard

 

[Bonairetrip]

follow this, BP w/ STA = -9lbs,
weights = -4lbs
regulator = -3lbs (approx)
fins / mask / computer = not sure

just counting these my wing needs to counter at least 16lbs of negative buoyancy. Seems to me I'm getting close to the 18lb wings limit. What other factors am I not considering?

IMHO, your result may be ok but your reasoning is flawed. If you think about it some more, the wing doesn't need to float a collection of everything you dive with that is negative.

Your wing has to do two things:
a) Float your rig and anything you attach to it (but not you) at the surface with a full tank. With the Oxycheq, you don't need a STA. Don't worry about the weights unless they will be attached to your plate. The same for mask & fins. (I have a 17# wing with Stainless plate, it works fine with an al 80 tank. The wing would be too small with a HP steel).
b) Float you at the time you are heaviest. That is a full tank with usually a compressed wetsuit.

So the math probably looks something like this:
a) The bouyancy (not weight) of (Plate + reg + harness hardware + full tank + STA if used). I have a 17# wing with Stainless plate, it works fine with an al 80 tank. The same wing would be too small with a HP steel.
b) If you are not overweighted, one rule of thumb: (The change in bouyancy of your tank full versus empty) + (The bouyancy of your exposure suit).

 

[Pullmyfinger]

See the aforementioned sticky, and then try searching.
There really is more than enough information out there
That will help you easily answer this one.

Mitch

 

[SeaFlea]

Well actually, in a worse case scenario the wing does need to support me and and all my attachments / equipment. i'm not sure I would want to ditch any of my equip. if left on the surface for a extended period of time.

After all, what else do we have to remain afloat if left to our own devices? Are you suggesting going for a nice long swim towards the the best option?

thx for you insight,

SeaFlea

 

[Hatul]

Greetings all, I need some of your feedback please.

I'm trying to decide between a 18lb Oxychec wing and a 26lb Hollis wing. Granted I do agree less is more from the airline weight allowance and the benefits of streamlined gear underwater but.........

follow this, BP w/ STA = -9lbs,
weights = -4lbs
regulator = -3lbs (approx)
fins / mask / computer = not sure

just counting these my wing needs to counter at least 16lbs of negative buoyancy. Seems to me I'm getting close to the 18lb wings limit. What other factors am I not considering?

Both wings cost about the same and both are very well made, no big difference there. I just am not sure if 18 will give me enough safety margin.

Please tell me if I'm overlooking something.

Thx, Good Dives, SeaFlea

I'm sure someone else will point this out but your reasoning is flawed. The reason for the name buoyancy compensator is that it compensates for buoyancy changes through the dive; namely from the loss of buoyancy in your wetsuit and the weight of the air you consume.

Adam

 

[TSandM]

Seaflea, if all the stuff you list is on your rig, I think you need the larger wing.

If you put the weights on a belt, you should be fine with the smaller wing.

 

[cool_hardware52]

Greetings all, I need some of your feedback please.

I'm trying to decide between a 18lb Oxychec wing and a 26lb Hollis wing. Granted I do agree less is more from the airline weight allowance and the benefits of streamlined gear underwater but.........

follow this, BP w/ STA = -9lbs,
weights = -4lbs
regulator = -3lbs (approx)
fins / mask / computer = not sure

just counting these my wing needs to counter at least 16lbs of negative buoyancy. Seems to me I'm getting close to the 18lb wings limit. What other factors am I not considering?

Both wings cost about the same and both are very well made, no big difference there. I just am not sure if 18 will give me enough safety margin.

Please tell me if I'm overlooking something.

Thx, Good Dives, SeaFlea

SeaFlea,

Wing calc's start with required weighting and required weighting (total ballast) starts with the buoyancy of your exposure suit.

You have told us nothing about your suit, and nothing about what cylinders you plan to use.

I should probably bite my tongue, but I feel compelled to add that your assumptions are seriously flawed.

Tobin