Neoprene Dry Suit question

[jepuskar]

Hi,

I am a new drysuit diver, got a whole 4 dives in my Neoprene Suit...all in the 25 foot range. My buddy and I decided to go down to 50 feet and see what affects this has on the suit, our bouyancy, and any other differences.

We just finished our previous dive with low tanks...about 400psi and 900psi...we did a weight check at the surface, my buddy was too negative and I felt I need a couple more pounds, so we made these adjustments for this 50foot dive, with full tanks.

So, on to the dive. We descend down the line. I noticed right away that I was really negative, full tank, just added a couple more pounds, so I start adding air to my suit, and adding air, and adding....I'm using the line as I am still dropping fast...we get down to 50 feet, I'm adding air to my suit like crazy...I inhale and still drop....

So now I am a big bubble of gas, and when I add air to my suit it burps out the neck seal and right into my hood, which causes cone head syndrom, so i press down on my hood to take care of that problem, but it keeps happening...all while still negative.

I added enough air in my suit at this point to where I felt something wasn't right. So I thumbed it and up the line we went...did a nice safety stop on the line and surfaced..dive lasted 5-7 minutes.

Here are my thoughts:

I was overweighted, but we weigh ourselves for a neutral safety stop at 15ft with 500psi left, I had 3000psi at the start of this dive, so I was 5-6 lbs overweighted...cant do much about that.
The Neoprene Suit compresses at depth so I needed to add more air to compensate for that.
My body attitude was more vertical, so all the air was towards my upper half....didnt realize my neck seal could burp air.

I'm thinking of using my drysuit to offset suit squeeze at depth, because that was not an issue and then use my BC to obtain neutrality. My suit exhaust is on my left wrist, so dumping air from BC and drysuit wouldnt be an issue.

Anyone else have similar experiences with a Neoprene Suit?

 

[matt_unique]

No surprises with your dive experience. All suits can burp air from the neck, something you need to be aware of and to execute in case the vent on your drysuit fails. Neoprene compresses with depth. If you were taught to use your drysuit for buoyancy it does not work for deeper depths. In reality we use both the drysuit and BC/BP for buoyancy because even adding a little air to the suit to prevent squeeze increases your buoyancy. So everyone actually uses both for buoyancy. As you noticed, as you descended you needed to add more and more air. You let your rate of descent get ahead of you. If you are not descending in a controlled manner stop immediately and kick up from that point if necessary, with neoprene the problem only compounds with depth of course. If you were to use suit only you would eventually be the Stay Puff Marshmallow Man

As you descend, add air to your suit first to stop the squeeze. Once you have added air to prevent squeeze at a given depth begin using your BC/BP to control your buoyancy. With alum tanks and neoprene dry you need a lot of weight (relatively speaking) for the most important depths - 20' to the surface. You may have been overweight but when properly weighted you will still feel overweight when you are at depth - it's the nature of neoprene.

--Matt

 

[jepuskar]

Thanks Matt. Yes, I was taught to only use my drysuit, but I was aware that its ok to use both, but didnt try that because I didnt think it was necessary, but now I see it is.

I was using the line the whole way down and up so my rate of decent and ascent was under control the whole time, but I was pretty negative...something a good inhale couldnt offset.

I am aware of burping air from the neck and wrist seals in an emergency, I wasnt aware that it happened without intervention ie: me yanking the seal back...so that was a good learning experience.

I was also aware that you get what you pay for, in this case I now understand first hand the draw backs of neoprene, but on the flip side....last year, i didnt get in the quarry until June...I have a full two months head start.

Thanks again Matt.

 

[matt_unique]

Thanks Matt. Yes, I was taught to only use my drysuit, but I was aware that its ok to use both, but didnt try that because I didnt think it was necessary, but now I see it is.

I was using the line the whole way down and up so my rate of decent and ascent was under control the whole time, but I was pretty negative...something a good inhale couldnt offset.

I am aware of burping air from the neck and wrist seals in an emergency, I wasnt aware that it happened without intervention ie: me yanking the seal back...so that was a good learning experience.

I was also aware that you get what you pay for, in this case I now understand first hand the draw backs of neoprene, but on the flip side....last year, i didnt get in the quarry until June...I have a full two months head start.

Thanks again Matt.

What I meant was your rate of descent was 'ahead of you' if you were using the line to manage the speed. What you would want to do is use the line as a guide to make sure you descend where you want to descend but do not use it to manage your descent rate. You would need to manage your descent (and of course ascent) rate with your buoyancy or kicking. Using the line to manage your ascent/descent is dangerous for many reasons but in heavy surf in can go slack and all of a sudden are floating up/down much faster since you cannot put any tension on the line. Know what I mean?

If you are head up your suit can vent without your intervention on the neck seal. What you have experienced is one of the drawbacks to neoprene but there are also many advantages. That is discussed on another recent thread as well.

Good luck with your suit.

--Matt

 

[DA Aquamaster]

In my experience, latex neck seals are far more prone to burping air in a vertical postition than neoprene seals. Your experience prompts me to ask if you folded the neck seal under or just left it flat against your neck?

If the top 1 to 1 1/2 inches of the seal is folded in against your neck, burping is unlikely to occur unless the seal is much too big for your neck.

I'd also second the suggestion to use the BC or wing to carry any air needed for bouyancy in excess of what feels comfortable in the suit.

 

[yknot]

First of all, not all neoprene seals are created equal. Some, like Henderson's, are meant to be a single layer and seal just like a latex seal would against your neck and wrists. Others are meant to be rolled under. The loop in the material this style creates acts as a pressure seal in itself. Another issue in regards to neoprene is that they can be worn comfortably at depth with less air than shell suits. Neoprene won't pinch your skin or bind up like shell suits can. Personally, I don't think neoprene dry suits compress and change in bouyancy nearly as much as a wet suit. There isn't the same type of solid surface inside the suit to compress against. The big change in bouyancy could be that, with too much air in the suit to begin with, it is that air compressing and causing bouyancy issues. I would continue to work on weighting. I also dive a neoprene suit and have found that with proper weighting I never need to add air to my BC. This isn't a decision I made as to whether to use the BC or not- it just works that way for me. When you were trying to figure your weight requirements you also may not have had all of the air out of the suit. I would nail the weight at the surface rather than at 15 feet. The best way to get it all figured out is to keep diving the suit and learning something from every dive. I found that the dry suit is more difficult to dive with than a wet suit. It definately took me more than 4 dives to get comfortable.

 

[jepuskar]

Matt,

Yes, I understood what you meant....I was using the line to control my descent which was done on purpose. I was aware of the drawbacks of neoprene, but I never imagined having to add THAT much air, so I was adding air, checking my buoyancy while using the line and finding myself wayy negative. I havent used a line since being certified, but in this case it aided my learning.

The line we used was tied to a huge floating dock, so it was safe as far as tension goes...plus it was in the quarry, so no other issues existed.

DA,

Yes, all seals were folded under, as we were taught. We have had no leak issues with any of our seals, so far...keeping fingers crossed. But I fold about 3-4 inches at my wrist and probably a little more on the neck...I was told to fold it under as much as possible on each.

We are going back Saturday for more diving, we have already discussed this thread and the suggestions made, so I'm sure using the BC will be a huge improvement.

I'll follow up after our dives for people who experience the same thing.

 

[jepuskar]

yknot,

Yes, and that is why we are diving as much as possible with our new suits.. We are inexperienced with all of this and we know that. Our type of suit does require the seals to be rolled under.

I will double check my buoyancy though and go from there.

Thanks,

 

[yknot]

jepuskar- is the dump valve automatic- meaning you can dial in the point at which it starts to to dump? Those valves can add another confusing dimension to the dive but if you suit has one, get your self neutral at 20 feet or so, open the valve until it starts to vent and then turn back one click. This will also help you to not add too much air.

 

[Green_Manelishi]

This is why it is important for the hose on your BC to be long enough that you can
reach the inflator on your drysuit without having to let go the BC inflator.