Calling all coldwater, how much lift for 7+7?

[movementality]

Quick wing lift question.

Disclaimer: I'm a noob, don't have ready access to a pool, don't know how much weight I'll need to keep neutrally buoyant yet, and all other similar posts (that I saw) referred to warm water wetsuits. Sorry to waste everyone's time rehashing an old issue, but any help would be greatly appreciated.

Wetsuit: 7mm Full + 7mm Hooded Vest
Rig: Assume large single steel tank, SS Plate (~5lb for the plate)
Noob: 5'9", 145lb.

I know the rig itself (SS BP, Steel tank) plus all my equip. probably won't surpass 30lb, so I'm good there, but I'm not sure about my wetsuit buoyancy.
I will be diving a 7mm full + 7mm hooded vest. Not sure how much weight I'll need to get neutrally buoyant since this will be my first equipment purchase and I didn't wear a wetsuit during the pool sessions (OW next month). I'm assuming 6-8 lbs extra weight to get neutral, but that's a number I pulled out of thin air.

I'm deciding between a 30# and 40# wing. I'm thinking 30, but thoughts of becoming a dirt dart flit through the empty space between my ears. I'm calculating for worst case scenario (no buoyancy from wetsuit, 30lb rig plus 6-8 pound ditchable weight that gets stuck) but I know if I'm even approaching that depth, I'll be diving a completely different rig with completely different training (and a better grasp on how to do this calculation properly).

Any help would be greatly appreciated. Thanks!

 

[landlocked]

Ah... what?

Will you be diving salt water or fresh? How much weight do you use in the pool sessions? When you did your pool sessions, did you have any trouble knelling on the bottom. I assume you are looking at dives around the 60 foot range. When are you planning on buying your backplate and from who?

Some quick givens. A 7+7 wet suit is far from neutral, think cork. Even with a SS back plate you will still be looking at somewhere around an additional 15 pounds or more just to be able to sink. What tank you use will also make a big difference, steel tanks being less bouyant than aluminum. (Tank size also makes a difference.) Also, the more you dive, the less weight you will need. As long as you are diving in a wet suit, the 30# wing should be fine.

I think where you may run into problems is warm water diving with a SS backplate and no neoprene. You may be a little too heavy in that case. You might want to consider an aluminum BP until you move into a dry suit.

In the end it is just going to take a number of dives and some experimenting to get your weights adjusted correctly.

 

[movementality]

I'll be diving saltwater, didn't have a wetsuit in the pool sessions so don't know my weighting requirements, and the BP/W I'm looking at is a DSS single tank rig to be purchased in the next week.

When I dive warm water, I will almost definitely still be in a wetsuit (though a thinner one) since I get cold easily, so I was thinking SS BP would do me well regardless. And in any case, if I do dive trunks only, I was thinking a 30 would still be able to counteract the negative buoyancy of the rig (I'll have an SMB doubling as a lift bag if a catastrophic wing failure happens).

At least that's my take on it. Please correct me if I'm way off kilter here, especially about the SMB "back-up" if wing failure does happen at depth without the built-in buoyancy of a wetsuit. I appreciate the input!

 

[Humuhumunukunukuapua'a]

Here's one thing that you're looking at askew. You will NEVER be in a situation to use your wing to ascend. You *deflate* your wing when you ascend. So a catastrophic wing failure really isn't catastrophic at all. This seems to be a common recurring misconception. You'll be able to swim the rig up even if the wing pops (with singles).

So it follows, you will never use your SMB to ascend. You'll just slowly kick on up.

The place where a popped BC becomes a problem is at the surface. That's where the SMB might come in handy or where you might ditch weight to keep your head above water. Think about how heavy you'd have to be to not be able to swim the rig up. Aint gonna happen.

I use my SS BP in warm water and it's nice because I don't need any other weight.

We've already talked about what to consider when choosing wing size, so I won't rehash, but I just wanted to clear up the issue regarding "wing failure at depth". It's something a lot of new divers seem to worry about, but it's not the issue.

Either a 30 or 40 pound wing will compensate for your wetsuit compression at depth. Either will also probably float you to your satisfaction at the surface (that's really the big question). If your wing fails at depth (SOOO unlikely its almost impossible because there's almost no pressure differential between inside and outside of the wing at depth), you may have trouble being neutrally buoyant (although probably not...most buoyancy control is with your lungs anyway) but you will not have trouble swimming the rig and yourself to the surface. Seriously, no worries.

When you're diving, your wing will be basically empty...maybe a little gas to compensate for wetsuit compression. But a BC really isn't your lifeline to the surface. It's a way to fine tune your buoyancy. When you ascend at the end of the dive, it'll be empty if you're weighted correctly.

I got a 40. Either would work. The big question is which will float you on the surface to your satisfaction. I'm 6'2", 215 pounds and a 40 is way more than enough for me in cold water. At most, it's a third full at the surface.

Hope that helps

Gregg

 

[movementality]

Landlocked, thanks for the input. Hum, thanks for catching the noob foul. Much appreciated to you both. Now, if only I could figure a way to grow gills and stay underwater... Any suggestions?