how much lift do I need?

[poomero]

How do you figure out how much lift you will need in a wing?

I dive with 18LBS
7mill suit
Back plate and wing
HP 100's
one tank only

How much lift do I need?

 

[Dive Right In Scuba 2]

18lbs in addition to the plate? SS or AL?

 

[Mr Carcharodon]

If you are average about 30 pounds. Most people are not exactly average however. Remember you need to float you, and your rig without you in it. Both at the heaviest possible point in the dive. For you that will be at depth when your wetsuit is as compressed as it can be. And for your rig that will be at the surface with a full tank. More wing than you need means more drag and harder swimming on every dive. Try to avoid that.

 

[Roman_66]

Remember you need to float you, and your rig without you in it.

I saw such phrase few times and never understand WHY?
Why equipment without diver must have positive buoyancy ?
Do you plan to swim on surface near your equipment ?
I think wing should lift diver with full equipment in worse point = on bottom on the start of the dive, when wet suit is compressed (10 lb for 7mm ? Maybe more..) and air weight (about 8 lb in HP100) + about 10 spear.

 

[Mr Carcharodon]

Sometimes to get onto a small boat you have to take your rig off. If your gear then sinks into the abyss that would be really unfortunate. Also in a rescue situation it is advised to remove kit from the diver distress to assure positive buoyancy. Losing their, or possibly your gear would once again be not so good. So there is one case where the total buoyancy is your wetsuit plus your BC, and another where it is just the BC. In an emergency of course the weights are going, to the extent that you have ditchable weights.

10 Spear? What's that?

 

[Roman_66]

Sorry, "spare"
Diver needs about 10 lb positive buoyancy to keep head over water.

 

[runsongas]

poom, there is a sticky for a spreadsheet at the top of this subforum

http://www.scubaboard.com/forums/bu...ems/158370-ultimate-wing-lift-calculator.html

if you are using a ss plate, you probably should go with the 32lb hog wing. the 28lb trianta is a bit small unless you are using an AL plate.

 

[mlevsky]

While we're on the topic (sorry if this is hijacking your thread OP, but it might be useful for you too if I've done it right). but I've been trying to do some calcs to buy a bp/w, and if anyone has the inclination to look over them and see if they make sense (all metric numbers, celsius etc). I'm thinking this is telling me that 30lb (13.4kg) is more than sufficient - is this sensible... I'm not sure about the adjusting for salt water.

23 degree salt water
Single AL80
5mm wetsuit
Max depth 30m
SS plate
Weigh 75kg

	30m (full)	3m (empty)
Regs	-1.4	-1.4
Tank	-1.8	1
Backplate	-2.7	-2.7
Knife/computer etc	-1	-1
Wetsuit	2	7.5
Salt Water	2	2
Subtotal	-2.9	5.4
Weights	-5	-5
Subtotal	-7.9	0.4
Wing	7.9	0
Total	0	0
Wing Failure	-7.9	0
Drop Weight belt	-2.9	0

 

[Keith.M]

Interesting thread poomero. You have received a lot of good advice.

Personally, I have been diving both wet and dry here in NorCal with a 32 lb wing with no issue.

I have been considering a 28 lb. as well, but in reality, I just bought a new 30 lb. which I think will be more than adequate.

So what were you using before? I am pretty sure you were in a steel plate.

Did you feel that you had too much, or not enough lift?

 

[poomero]

I was just wondering. I was in a 32# hog wing with a SS backplate and it was fine. I just wanted to bring up the topic and see what people think.