Bouyancy control BC or DS?

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Pez7378
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Bouyancy control BC or DS?

Post by Pez7378 » Fri Jul 14, 2006 1:20 pm

So I just had to take my new DS out and get wet (for the first dive in a long time! \:D/ ) Everything went great except the next day I found out my dive buddy broke his finger before the dive. #-o Now, I have not had a DS class and only planned on going no deeper than 30 fsw. Max depth ended up being 45fsw but only for a minute before we turned around. I felt very comfortable right away with my suit and controlling bouyancy. But I want to know what the consensus is out there as to whether or not I should use the suit for Bouyancy, or the BC. I don't think I will have a problem figuring it out either way and I know that most agencies teach to use the suit for BC but what exactly are the pros and cons of each?

BTW I am going to absolutely LOVE diving dry!! :supz: :supz:

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Post by Pinkpadigal » Fri Jul 14, 2006 1:48 pm

Pez,

Most books you will read, dive agencies and DS manufacturers will tell you to use your drysuit exclusively for buoyancy. Many divers will agree. I actually use both. Because I multilevel dive a lot, I adjust with my drysuit at depth but fine tune, if necessary, with my BCD. That is what works easiest for me but you will find what works best for you.

I have dove Harveys, USIA, Apollo, OSSystems, DUI and Seasoft suits. I have found it easier to control buoyancy in neoprene suits (Harveys, Apollo and Seasoft) than in bag (USIA and OS) or Trilament suits (DUI). Mainly, because air can get trapped and it is harder to vent.

You can take a DS class but the only way you will know how to use your drysuit is to dive it. If you continue to dive the suit without the class, make sure that your buddy knows how your drysuit works in case of an emergency. I would avoid going deep until you are totally comfortable with how the suit works and getting air out of the suit.

Good luck, and yes, diving dry ROCKS!
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Tom Nic
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Post by Tom Nic » Fri Jul 14, 2006 2:03 pm

Diving Dry is Awesome! :supz:

I dive a USIA suit, and put air in to offset squeeze. Like Pinkpadigal I mostly use my BC to fine tune my buoyancy.

For me personally, I can't imagine using ONLY my drysuit for buoyancy control. I am, after all, wearing a BCD, (Buoyancy Control Device).

Using both you are managing two airspaces, and you need to practice and practice and get comfortable controlling your buoyancy. Like most other things in diving there are skills to be learned, practiced, and fine tuned.

Congrats on your suit! :supz:

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Post by Grateful Diver » Fri Jul 14, 2006 2:22 pm

After using my drysuit for buoyancy control for about 600 dives, I decided to try doing it the other way. I found that when I put minimal air in my drysuit (just enough to relieve the squeeze) and used my BCD more, I had far better overall buoyancy control. I could orient myself vertically without feeling an air bubble in my shoulders, I could change position easier without having to struggle with air that was shifting from one end of my body to the other, and I could invert without having a bunch of air trying to squeeze itself into my boots.

My suggestion is to try it each way for about a dozen dives and decide for yourself which seems easier.

... Bob (Grateful Diver)

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Post by Tangfish » Fri Jul 14, 2006 2:44 pm

I too use the suit only to relieve the squeeze (and if I'm cold, I might add a bit more), using the BCD for buoyancy control. I'd take GD's recommendation and give it a go both ways before deciding what works best for you. :book:

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Post by Maverick » Sun Jul 16, 2006 7:41 pm

First off i dive a shell suit. I tried the ds bouancy and hate feeling the air move around, so i tried the bcd and only the suit to relieve the squeeze. it is my choice now, but i did just what GD said try both, it won't take you long to find out what you prefer.

Mav.

PS and if you still can't decide we will tell you how to do it. \:D/
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RE.

Post by Diver_Dave » Mon Aug 07, 2006 9:49 pm

I use my drysuit because I dont use a B.C. just use a soft backpack..Image
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Post by Aquanautchuck » Mon Aug 07, 2006 11:01 pm

I tried both but very fast discovered that just putting enough air in my dry suit to reduce squeeze and my BCd for buoyancy worked. Another issue I discovered is when you use your dry suit for buoyancy is multi tasking under stress. Most dry suits do not dump air very fast. I discovered while doing skills that trying to dump air out of the dry suit and the bcd at the same time is very hard.

When I ordered my DUI CF200 I ordered a cuff dump. I may get a damp arm once in awhile but when I need to dump air fast it works great.

Just my 2 cents worth.
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Last edited by Aquanautchuck on Tue Aug 08, 2006 9:09 am, edited 1 time in total.

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RE.

Post by Diver_Dave » Tue Aug 08, 2006 3:27 am

With a custom fit dry suit that fits snug u dont need a lot of air in your suit to keep u neutral bouyant if u r weighted right :bootyshake:
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John Rawlings
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Post by John Rawlings » Tue Aug 08, 2006 7:41 am

I agree with GD above when he says to try it both ways to see how you prefer controlling your buoyancy, and Maverick when he said that "it won't take you long" to figure out which way you like.

However.....if you think that you will ever be interested in technical diving, I would suggest starting right now with using your BC or wing to control your buoyancy and add only enough gas into your drysuit to maintain comfort. while many divers easily and happily use their drysuits to maintain buoyancy, drysuits are not, repeat NOT, designed to effectively control buoyancy when wearing double rigs and the extra weight that entails.

My personal choice (and I'm BIG on divers making their own reasoned choices for themselves) is to strictly use my BC/wing for buoyancy control. I only add air or argon to my suit when I begin to feel discomfort from increasing pressure and/or cold, and then only enough to relieve the discomfort. Using your BC or wing for buoyancy will allow you to more subtly fine-tune your buoyancy, whereas the sheer size of the typical drysuit will allow large volumes of gas to shift within the suit itself, (the exception to this being a "tailored" custom suit like Diver Dave's that he shows in his pic above), causing instability.

Good luck and have fun while you "test" each way!

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Post by BASSMAN » Tue Aug 08, 2006 1:34 pm

DrySuit to relive squeeze.
BCD for control.(Works for me.)
Thats my 2 cents.

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Post by Joshua Smith » Tue Aug 08, 2006 2:05 pm

I tried it both ways and quickly chose to use my BC for buoyancy, and suit to relieve squeeze/stay warm. There are some very skilled divers who use their suits, though.
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Post by lamont » Tue Aug 08, 2006 11:36 pm

i add enough to get all the squeeze off, but if there's any bubble in there at all i vent it out. i do like getting my money's worth out of my custom cut 400g DUI thinsulate, i spent way too much on it to crush all the thermal properties out of it... i don't like having an air bubble in my drysuit though...

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Thanks!

Post by Pez7378 » Fri Aug 11, 2006 6:30 pm

Thanks for all the replies and advice. I am still trying to work the bugs out and Grateful Diver got to see it first hand last week. While attempting a safety stop I lost control and corked to the surface. GD came up and asked, "did you just add a bunch of air to your suit?" I hadn't but when I looked at my arms I looked like the hulk. #-o Silly me, no wonder my BCD wasn't venting. Hopefully after this weekend I will have had more than enough practice to have figured it out (GD's :prayer: AOW class). I think I can fully understand the logic of using the BCD as it is intended.

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Post by rcontrera » Fri Aug 11, 2006 11:02 pm

Using both for control is much more complicated than just using one or the other.

In a shell style suit, when the proper weight is worn for neutral buoyancy, insulation directly tracks buoyancy.

As you go down, the air compresses and you lose insulation and buoyancy. Touch the inflater to restore your insulation and... vwala ... buoyancy is restored as well.

If you EVER have a bubble roaming free from your undergarments, you are either over inflated or over weighted.

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Post by lamont » Sat Aug 12, 2006 6:54 pm

rcontrera wrote:If you EVER have a bubble roaming free from your undergarments, you are either over inflated or over weighted.


it took me awhile to figure out how to tell if i had a bubble (some bubbles are obvious, others not so much in your first few drysuit dives).

generally to first order if i can make it vent out, i want it out. i might tap a little bit of air in since you can get a bit of squeeze on even holding depth and just venting. i only put in enough to form a little bit of a bubble if i'm cold.

i just noticed today that i do all kinds of little cheats, though... like if i slip a little lower so that a full inhale isn't moving me back up very fast, i'll tap my drysuit inflator to get a little lift and then vent out my shoulder after i start moving up. that's a very fine-grained cheat that i use though...

usually i'll also get myself neutral with the wing at 10-20 fsw by hammering on the inflator, then below that down to 50 fsw-ish i tend to predominantly use the drysuit inflator, and after that i trade off as needed...

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Post by rcontrera » Sun Aug 13, 2006 11:55 am

Undergarments can only trap so much air. After they are "saturated" with air, all extra air gathers at the highest point on the body in the form of bubbles. It's these bubbles that have caused so much trouble to new (or clueless) drysuit divers. It is important for us to find out just exactly how much air our undergarments are designed to hold and weight ourselves accordingly.

I have been in the drysuit business for over 25 years and cringe when I hear someone (even some instructors!!) tell a new diver to "...just add 10-15 pounds to your weight belt" to a new drysuit diver. WRONG!!!!

The best thing a new drysuit owner can do to figure out the suit is to just go snorkel for a little while. By jumping in with nothing but mask, snorkel, fins and the suit system, you are most likely not going to get very far under water, but will move the air around and will "thrash" the excess out of the undergarment. I should have mentioned that, if using an adjustable auto dump valve, you need to loosen the dump spring to it's weakest point so that any and all excess can be expelled easily.

Now, float upright and there will be about a pound or two difference pressure between your feet and your head. This will push more of the excess air out of the suit. Once those shoulder bubbles are vented off, you have the optimal amount of insulation in your suit in that the undergarments can't effectively hold any more air. THIS is the point where we don the rest of our gear and weight for neutral buoyancy.

With that all done, if you are still cold on a dive, then add additional undergarment layers and weight yourself again.

With loss of the insulation layer on a dive, we have insulation control by adding air to the suit. Buoyancy tracks perfectly with insulation so adding air to the BCD is not necessary.

(Stepping down from soapbox)

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Re: Thanks!

Post by Pez7378 » Tue Aug 15, 2006 6:19 pm

Pez7378 wrote: Hopefully after this weekend I will have had more than enough practice to have figured it out......


Oh was I right. I definately figured it out, and learned some things about which direction to turn the vent #-o .
(FYI + = Bouyant/Closed not vent more!!) I never did understand Canadian........ I may have also had a bad inflator hose. Switched it out, and everything worked very good. Now to fine tune things a bit. And the only way to do that is to GET OUT AND DIVE! Hmmm maybe next weeks club dive.

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