Wing Lift - Cold water, 8/7 semi-dry suit

[-JD-]

Hmm, can you explain the weight belt only situation?

I didn't plan for all of it to be weight belt. Just noted I intended on using one. For example, I bought an S/S plate.

Even if "properly" weighted, you can be very negative at depth, especially early in the dive due to the loss of buoyancy from the compressed suit and the weight of the gas in the full tank). In the case of a "catastrophic" wing failure (i.e. the corrugated hose comes off or the like ) where you can't maintain air in the wing, you can be hard pressed to not sink/go up.

You need to reduce negative buoyancy to the point where you can "swim it up."

Ideally you have some other form of inflatable buoyancy that is adjustable. A drysuit or a wing with a second, redundant air cell are two common ones. A smallish lift bag is a trickier option.

The last ditch option is reducing ballast weight - ditching. The problem is that that ditched weight is gone for that dive and as you rise, your suit will re-expand, continually increasing your net buoyancy. If you become significantly positive you have a runaway ascent that you may not be able to control by swimming against it and you risk DCS.

With all of your ditchable weight on a weight belt,you pretty much have to ditch all of it or keep it on. (Arguably, if you have a reasonable bottom depth you could plunk down there and un-thread some of your weights if you have the effective dexterity (cold/gloves) but I wouldn't count on it.) If ditching it makes you net-positive, even at shallower depths, then you have a high risk for a runaway.

Smaller weight groupings that are individually ditchable gives you some flexibility.

 

[mtoyama]

Even if "properly" weighted, you can be very negative at depth, especially early in the dive due to the loss of buoyancy from the compressed suit and the weight of the gas in the full tank). In the case of a "catastrophic" wing failure (i.e. the corrugated hose comes off or the like ) where you can't maintain air in the wing, you can be hard pressed to not sink/go up.

You need to reduce negative buoyancy to the point where you can "swim it up."

Ideally you have some other form of inflatable buoyancy that is adjustable. A drysuit or a wing with a second, redundant air cell are two common ones. A smallish lift bag is a trickier option.

The last ditch option is reducing ballast weight - ditching. The problem is that that ditched weight is gone for that dive and as you rise, your suit will re-expand, continually increasing your net buoyancy. If you become significantly positive you have a runaway ascent that you may not be able to control by swimming against it and you risk DCS.

With all of your ditchable weight on a weight belt,you pretty much have to ditch all of it or keep it on. (Arguably, if you have a reasonable bottom depth you could plunk down there and un-thread some of your weights if you have the effective dexterity (cold/gloves) but I wouldn't count on it.) If ditching it makes you net-positive, even at shallower depths, then you have a high risk for a runaway.

Smaller weight groupings that are individually ditchable gives you some flexibility.

Thank you for the explanation. This makes sense to me/

Is this why a "balanced rig" is important?

In the buoyancy calculator there were some cells saying "You'll be this negative at this depth, can you swim this much weight up off the bottom?" Sounds like it was alluding to this kind of scenario. I am a pretty strong swimmer, but have no idea how much weight I could swim up. And in an emergency, powering a bunch of weight up doesn't seem like a good idea.

 

[Brett Hatch]

Dan at Diver Dan's was confused about my problem (I didn't buy it from them, but I did discuss it with him while helping my gf with wetsuits). The suit seems to fit well when dry. Seals are good and tight. Not much extra room. There's a little bit of bulging at the zipper when I move my arms, and a little room in the neck.

Sounds like the suit is a good fit, then.

I did a surface swim out to Tanker's (urchin culling). Comfy during swim. Pretty sure there was 0 water in the core of my suit when I dropped down through the thermocline to 30', temp 53F. Then, it felt COLD. Like I was in a very cold room. Not like there was water exchange, just everything felt cold immediately.

First off, thanks for doing your part to contribute to the urchin culling experiment! Keep in mind that when you drop down to 30 feet, the pressure is double versus at the surface, so the suit will compress to maybe half to two-thirds its surface thickness. That brings the ocean a few mm closer to your body, which reduces the insulating properties of the neoprene by a little bit. So suit compression can explain some amount of chilliness. Also, any air trapped inside the suit will have either compressed to half its original size, or escaped entirely, which would cool you down a bit as well.

Maybe I should have waited a little bit for the space in the suit to heat up but I ended up intentionally flooding the suit to get water next to my body to warm up. When I flooded it, it felt like there was no water inside as I could feel it running down my back.

Hmm, I'm with Diver Dan, I don't get this. Wetsuits do not need water in them to keep you warm, every drop of water that does get in will make you a little bit colder. So flooding the suit to get water next to your body will not warm you up. This is a common misconception. Or, maybe I have misunderstood what you're saying.

MLL in SolaFx seems to be a great size for me based on the numbers and we're approaching Diver Dan's sale window, so that's my fallback. Not ready for dry suit yet

If the fit is substantially better than your Bare, then it might help. But fit aside, these 2 suits are practically the same thing. I hope the 3mm helps.

There is a way to simulate the issue @-JD- is concerned with, which is definitely a safety concern. Go to a site with a hard bottom at the deepest depth you normally dive. Maybe N. Monastery, or outside the cove in Pt Lobos, for example. At the beginning of the dive, your tank will be full, and at a deep depth, your suit will be very compressed. This is the most negative you can be, so is the worst case scenario for a wing failure. Find a spot on the hard bottom where you won't disturb any life there, and completely empty your BC / wing. You should be able to swim upward.

If you cannot do so, then you should consider how you would handle such a scenario were your wing to actually fail. In a wetsuit, your best option might be a pretty bad one -- dump weight. If that's the plan, then you will want to be able to dump just a little at a time, like 2-4 lb increments. Just enough to let you swim up off the bottom. Once you swim up a little, like 10 or 20 feet, your suit will begin to expand, which will make the rest of the ascent less work, but you may be dangerously buoyant as you reach the surface, since you dumped the weight at the bottom. So the less you had to dump, the safer you'll be in the last 10-30 feet of ascent, which are far and away the most dangerous part for DCS or AGE injuries.

BTW if you do this test, you don't need to swim all the way up to the surface, and you certainly don't need to actually dump your weight. Just empty your wing and see if you are able to swim up 20 feet or so off the bottom, and then continue on to enjoy your dive.

 

[SaltyFrog]

Even if "properly" weighted, you can be very negative at depth, especially early in the dive due to the loss of buoyancy from the compressed suit and the weight of the gas in the full tank). In the case of a "catastrophic" wing failure (i.e. the corrugated hose comes off or the like ) where you can't maintain air in the wing, you can be hard pressed to not sink/go up.

You need to reduce negative buoyancy to the point where you can "swim it up."

Ideally you have some other form of inflatable buoyancy that is adjustable. A drysuit or a wing with a second, redundant air cell are two common ones. A smallish lift bag is a trickier option.

The last ditch option is reducing ballast weight - ditching. The problem is that that ditched weight is gone for that dive and as you rise, your suit will re-expand, continually increasing your net buoyancy. If you become significantly positive you have a runaway ascent that you may not be able to control by swimming against it and you risk DCS.

With all of your ditchable weight on a weight belt,you pretty much have to ditch all of it or keep it on. (Arguably, if you have a reasonable bottom depth you could plunk down there and un-thread some of your weights if you have the effective dexterity (cold/gloves) but I wouldn't count on it.) If ditching it makes you net-positive, even at shallower depths, then you have a high risk for a runaway.

Smaller weight groupings that are individually ditchable gives you some flexibility.

Would a DUI weight harness solve this problem?

The idea is that one puts loose soft/hard weights into the pockets, then when catastrophic loss of buoyancy happens, one can throw away weights 2lb or 3lb at a time.

 

[runsongas]

trim weight pockets with 2 to 4 pounds inside are another option as long as you can reach them and pull the weight out.

 

[-JD-]

Is this why a "balanced rig" is important?

Yes, you should be able to swim up a balanced rig. The buoyancy swing of thick wetsuits wreaks havoc with the concept. I frequently see a drysuit as the advocated solution.

In the buoyancy calculator there were some cells saying "You'll be this negative at this depth, can you swim this much weight up off the bottom?" Sounds like it was alluding to this kind of scenario. I am a pretty strong swimmer, but have no idea how much weight I could swim up. And in an emergency, powering a bunch of weight up doesn't seem like a good idea.

Exactly. 10 lbs negative is frequently bandied about as what a strong swimmer should be able to swing up.

This gets really sketchy in my mind if you have a really deep bottom where dropping into it becomes a one way trip. The descent needs to be arrested FAST.

 

[-JD-]

Would a DUI weight harness solve this problem?

The idea is that one puts loose soft/hard weights into the pockets, then when catastrophic loss of buoyancy happens, one can throw away weights 2lb or 3lb at a time.

If you can distribute the weights and drop them independently than yes.

I split my ditchable weights into dumpable pockets on my waist belt. But I have considered trying a weight harness for drysuits or thick wetsuits.

Redundant buoyancy (Dual bladder wing, drysuit, etc.) strikes me as the best FIRST option. I dive with dual-bladder wings with both single and double tank configurations (secondary is manual-inflate only for me).

 

[johndiver999]

You don't understand about wetsuits. You do not want water in the suit, it will make you cold unless you pre-fill with very warm water.

What you are probably feeling is the result of colder water at depth and suit compression. the combined effect means that you will begin to feel the cold over your whole body. You lose heat through conduction.

 

[mtoyama]

You don't understand about wetsuits. You do not want water in the suit, it will make you cold unless you pre-fill with very warm water.

What you are probably feeling is the result of colder water at depth and suit compression. the combined effect means that you will begin to feel the cold over your whole body. You lose heat through conduction.

Yeah, I wasn't sure what was going on, as I haven't really felt that before. It was odd. I hadn't worn a semi-dry so it felt different. And it felt shockingly cold. So I let water in, and I was warmer at the end of the dive than at the start of the dive. Post hoc ergo propter hoc, perhaps.

I will not do this next time. I think I simply got cold because it got colder, and didn't let the suit work. I must let the suit work.

 

[mtoyama]

First off, thanks for doing your part to contribute to the urchin culling experiment!

Yes! My last 6 dives have been out there! I love it. Honestly it's what's motivating me to buy my gear: I learned I want to do dives with a mission, and what better mission than conservation work?

Are you trained up?

Keep in mind that when you drop down to 30 feet, the pressure is double versus at the surface, so the suit will compress to maybe half to two-thirds its surface thickness. That brings the ocean a few mm closer to your body, which reduces the insulating properties of the neoprene by a little bit. So suit compression can explain some amount of chilliness.

This I wasn't thinking about. Honestly, I've never really had a not-cold dive in California waters, wearing all kinds of rental suits. I might just be susceptible to cold.

I am diving on Friday and I'll see how it feels before I add the vest. Also after learning more about the buoyancy properties of neoprene I'm hesitant to add the 3mm vest to solve the problem now.