Loss of Buoyancy from Flooded Drysuit

[the_dragon_no1]

Very well put DaleC !
Yeah im a cold water solo diver myself (shallow shore only), so that's why im interested in learning more about this..
And now i just remembered from washing my undergarments (350g), it gets HEAVY when it's very wet...

 

[RJP]

it will be "more negative" than before the water gushed in. In other words, it was previously positively buoyant, and now that water has gushed in it is neutrally buoyant. So it is not "negative", but it is more negative than it was before the water entered.

This would only be true if the suit were both completely FULL of water and completely DEVOID of air. As has been pointed out above, that's really not possible absent a catastrophic failure... of almost all seams.

Think about it this way, if your suit has a 2cu-ft air bubble and springs a leak which allows water in - however much water you like - that water is neutrally buoyant. Your suit still has a 2cu-ft air bubble in it. You are no more negative than you were prior to the water entering the suit. Your buoyancy is unchanged.

 

[TSandM]

In a full flood, a lot of the air spaces in your undergarment are displaced by water. You DO lose lift from the undergarment (which is most of the lift in a dry suit, if you are properly weighted). You won't lose it all, but you may lose a good deal of it.

You can determine how much lift your dry suit and undergarments have by getting in the water without your gear, and seeing how much lead you can hold without sinking. That's the maximum amount of lift you can lose from a flooded suit. My suit is 28 pounds positive with a typical amount of air in it.

 

[drbill]

The only time I have dived my "dry" suit I had about 4-5 gallons of water fill the legs. I had little trouble swimming underwater back to the dive park stairs (using a 30 lb wing) although I looked like the Pillsbury Dough Boy when I tried to climb them with my dry suit legs "super saturated." The laughter from the other divers at the park didn't help either! The one good thing about that dry suit experience was I had no concern about air getting trapped in my legs and causing a feet first ascent.

 

[Rich Keller]

I am trying to determine the proper size of a wing, and one if the contingencies I'm planning for is a flooded drysuit. Does anyone have an idea how much buoyancy I lose when my drysuit (a DUI FLX), that I usually keep minimally inflated to avoid a squeeze, floods? In that case I need enough spare capacity in the wing to make up for it, but I don't know how much that should be.

You would be better off with a neoprene dry suit so even if it does flood you still have enough lift to get you to the surface without having to depend your wing. For example the same thing that rips your suit also rips your wing, all you need to do is drop your weights and you will get to the surface.

 

[MXGratefulDiver]

I know of two cases where people went in off a boat with their drysuit zipper open ... can't get much more flooded than that. In both cases they were able to maintain buoyancy at the surface long enough to get out of the water. It's the getting out part that's hard ... because that's when the water gets really heavy.

I do wonder what would happen if you inverted and hit your drysuit inflator button. This would be functionally similar to clearing your mask, as the air would go directly to the highest point in the suit, which if you were inverted would be your feet. Would it force water to come out your dump valve? Hmmm ... I might have to try this sometime just to see what happens ...

... Bob (Grateful Diver)

 

[darushin]

Seems to me there is a fairly straightforward test.

Get in the pool with your normal configuration of gear, except drysuit. Find the minimum of amount weight you need to submerge.

Do the same, but with your drysuit. You will need more weight to submerge, and that difference is how much buoyancy the drysuit provided.

This is a good test but doesn't take into account the undergarments, although I am not sure if any undergarments out there today are negative. An easy test would be put them in a deep enough container (ex pool) and see if your under garments sink. If they do then you will need to add that into the mix.

 

[TN-Steve]

I know of two cases where people went in off a boat with their drysuit zipper open ... can't get much more flooded than that. In both cases they were able to maintain buoyancy at the surface long enough to get out of the water. It's the getting out part that's hard ... because that's when the water gets really heavy.

I do wonder what would happen if you inverted and hit your drysuit inflator button. This would be functionally similar to clearing your mask, as the air would go directly to the highest point in the suit, which if you were inverted would be your feet. Would it force water to come out your dump valve? Hmmm ... I might have to try this sometime just to see what happens ...

... Bob (Grateful Diver)

Bob,

In all honesty, if you do, I'd appreciate it if you filmed it, it might be good learning point. Of course, if you're that flooded, even getting the water OUT would just mean that you'd fill right back up again. Sort of like clearing your mask if the dreaded "purge valve" has rolled over on itself.

Enjoy your Red Sea trip.... envy you.

 

[MXGratefulDiver]

I already enjoyed my Red Sea trip ... got back this week-end. I've posted some pics in the photography forum, if you're interested.

... Bob (Grateful Diver)

 

[RJP]

the air would go directly to the highest point in the suit, which if you were inverted would be your feet. Would it force water to come out your dump valve? Hmmm ... I might have to try this sometime just to see what happens ...

(Grateful Diver)

It forces the water out through the neck seal. Don't ask me how I know this.