How much lift margin?

[guruboy]

How much lift margin do you guys like to have?

For example- 30# negative at the start of the dive. Do you go with 40# or 60# wing?

 

[sea_otter]

This might be a dumb question but why are you 30# negative at the start of a dive? Is that at depth with a very squeezed wetsuit or flooded drysuit? Or just a huge amount of gas?

In doubles I am about 15# negative at the start of a dive. I use a 40# wing. It is just enough to float my gear (full tanks) at the surface without me in it and enough to float my head comfortably above the water with me in it. I had a 55# wing and found it uncomfortably large.

 

[_Ralph]

The propeller head answer .... slightly more lift than the weight of gas in your tanks

The real answer ... slightly more lift than what the propeller heads say .....


Based on diving a "balanced" rig

I have a 32lb singles rig and a 60lb doubles rig (only because I mainly dive 8" double tanks .. my 7" double tanks would be better suited with a narrower wing, but i'm frugal with owning too many things of one nature ... 2 is my limit of like things .... ). Both are sufficient in the "hold lots of gas" category for my diving ... and then some

_R

 

[tbone1004]

@sea_otter double 121's cave filled with a deco bottle will have 30lbs of gas in there not including any other buoyancy factors. Not that difficult to get to 30lb lift required with doubles, even diving a balanced rig.

@guruboy 30lbs negative would have me around 50lbs. 40lbs won't be enough to keep most of your head out of the water if you're in choppy water

 

[guruboy]

Floating the gear without me in it is a good point. Hadn't considered that.

Thanks for the empirical data point.

 

[sea_otter]

@sea_otter double 121's cave filled

Next time I'm bitching about how heavy my tanks are, I'll conjure up that image. Here I thought HP120s were absurd. That's more tank than me... I'll stick with the 85s.

 

[cool_hardware52]

How much lift margin do you guys like to have?

For example- 30# negative at the start of the dive. Do you go with 40# or 60# wing?

Keep in mind Buoyancy Compensators are used to compensate for things that lose buoyancy as you descend.

Ballast is used to overcome net buoyancy when your gas load is at a minimum.

There is a relation between these two, but it's worth looking at and understanding each separately, then considering how much lift you might require.

Tobin

 

[guruboy]

That's a good point for people to keep in mind.

I already know how much minimum lift I will need at the start of a dive with a balanced rig.

Just curious what the real world practical considerations of required vs desired lift are.

 

[Michael Guerrero]

For single tank, I dive with a 30# wing, for LP85s with only an AL40 side slung, I'm good with a 40# wing. In my HP133s in a drysuit w/ two deco bottles, I use a #65lb wing.

That's as much thought as I put into it.