troubles with weight and bouyancy?

[Thrillhouse]

Hi,

My buddy and I recently got certified through our uni's dive-club. We've done 8 open-water dives total in cold water (Vancouver), wearing shell-suits for 7 of them. The issue we've both been having is about weight. I'm about 135 lbs, he's maybe 150 lbs. I wore 38 lbs last dive, he wore 40 lbs, which surprised the divemasters who took us out on the club-dive, considering we're not big guys and that (apparently) is a lot of weight.

The thing is, we've both had trouble with keeping bouyant, and will often begin to float to the surface when around 20 ft after getting down to about 1200 psi... The last dive we did was terrible. It was murkey and at night, and with 38 lbs I was over-weighted and contstantly banging into the rocks and silt. Still, my two biggest concerns are not having a runaway ascent and not struggling with sinking!

So far we've both kept relatively shallow for our first few dives, but I'd like to start getting down to 50 or 60 ft now that I'm getting more comfortable underwater. Still, I have trouble staying bouyant, and am often afraid to releave the squeeze of my shellsuit by inflating air into it in the fear that it won't vent fast enough as I slowly surface, causing me to shoot up and get bent. How real is this concern? To be honest, I feel stupid asking my old instructors, since it seems somewhat obvious. Also, we were told to rely on our drysuits for bouyancy underwater instead of our BCDs, but the BCD is so much more accessable to purge than having to reach across the chest and press/unscrew the shoulder-valve on the suit itself.

I'd like to get going deeper, but need some assurance I'm not going to sink into an abyss or shoot upwards... Any suggestions as to how much weight a guy of my build should be using, and good tips for maintaining bouyancy?


[EDIT: I use 38 lbs, which is including my integrated weights (24 lbs), two ankle weights and additional ones in the pockets of the BCD]

 

[Fabulous]

Well we do we start.

First hello to SB and your first thread/post.

Second, suggest you fill out your profile fully before the SB police arrest you.

Thirdly, I don't feel qualified to answer your questions apart from saying I think your instructor who certified you and your buddy is in trouble.

I hear help coming

 

[meesier42]

In this type of situation your instructors or at least more expirienced friends are your best friends here, since it sounds like you might have 2 or more contributing factors.
Generally instructors want you to enjoy diving and to dive safely and would rather spend time with you then read about you getting hurt in the paper.

As I have never been trained in drysuit diving I can't help.

 

[Doc Intrepid]

Thrillhouse, the issues you and your buddy are dealing with are not unusual. So item one is to relax, things will get better over time.

Drysuits in cold water are often interesting because first you tend to wear a heavier undergarment requiring slightly more loft and second you tend to put slightly more gas in the suit than in warmer water. In a DUI450 wearing a Weezle divers I know routinely use 12 lb plates and a 10 lb V-weight, for a total of 22 lbs (in addition to two steel tanks - which are likely significantly heavier than what you are using).

There is no doubt that 38 and 40 lbs of weight is significant. I suspect you both are overweighted. But many new divers find that they require less weight over time as they begin to relax in the water...and you and your buddy are new divers. You may find this weight requirement diminishing naturally as you conduct more dives and gain experience.

On one hand, you need what you need to establish equilibrium with whatever equipment you are using. On the other, you need to make reasonable efforts to ensure that you have made every attempt to reduce your inherent bouyancy as much as possible. This might include things like ensuring that you dive your suit with a little bit of a squeeze on - e.g. ensure you are not putting too much gas into your suit, and looking at your BC with a critical eye - if your BC has a large amount of padded shoulders, padding in the spine area, or padded shoulder straps, generally speaking this padding adds bouyancy. There are other options available that may work better for you.

One of the concerns I would have in your situation is most of your weight is in your BC - either in its weight-bearing pockets, or the extra weight you've put into the regular pockets. I have seen weight-bearing pockets accidentally become detached from the BC during the dive, and have seen weights fall out of pockets when the diver goes inverted to look at something. Neither would be good in your situation. Consider redistributing some of your weight onto a weightbelt or a weight harness, so you don't carry all of it in your BC.

Weight yourselves when your tanks are nearly empty, not when they are full. You are finding yourselves uncontrollably light as your tanks empty during the dive. Aluminum 80s have a swing weight of around 4-5 lbs depending on the tank, so you are becoming 4-5 lbs lighter as the dive progresses. Weighting yourselves with near empty tanks will prevent this from giving you problems.

You are smart to be aware of the fact that your suit will not vent gas as efficiently as your BC. Use your BC as your primary bouyancy control device. Put only as much gas in your suit as you need to offset squeeze - this reduces the amount of gas that you would need to vent on a runaway ascent to as low as reasonably achievable. Ensuring that you are properly trimmed will reduce the chance that all the gas in your suit will migrate to your feet, where it cannot be vented and you would find yourself heading to the surface feet first. Reducing gas in the suit and maintaining proper trim are part of the 'situational awareness' you need to cultivate in order to dive your suit safely at deeper depths.

Don't be in a hurry to get deep. It takes quite a few dives to dial in your suit under all conditions and situations. Work your way down deeper with your buddy, making sure you feel comfortable with the suit as you gain experience. Finally, if you find yourself with questions you can always ask on SB - but I'd recommend that you also ask your instructor. You have very little to lose and potentially much to gain by bouncing issues off your instructor.

Best,

Doc

 

[verybaddiver]

bah, i can offer some advice

1/. 38/40lb is a huge amount of weight, for any1 to be using, as since you both are fairly lighweight, this seems stupidly high.
2/. using the dry suit for buoyancy isn't the greatest idea. The bc is designed to compensate for buoyancy changes (HENCE THE NAME). the dry suit is best used only to relieve suit squeeze.
3/. If you are having trouble at shallow depths don't even consider going deeper, you wont see much more, and you are putting yourself under uneccessery risk.
4/. You shouldn't of been certified if you are still having these concerns, to be honest.


"but the BCD is so much more accessable to purge than having to reach across the chest and press/unscrew the shoulder-valve on the suit itself"

What kind of drysuit requires screwing a shoulder valve? surely it should self-vent if set correctly? Again i agree with you using the bc to control buoyancy, but use the suit to remove the squeeze, as this is dangerous as well, but not as dangerous as uncontrolled ascents.


--------
weighting depends on so many things, so it's quite hard to give an estimate
i use 4th element xerotherm artics/jetfins/canlight/single 12 steel faber and require ~8 pounds if thats any help.

 

[SharkDiver36]

Lots of advice I could probably give and at least one piece of advice I know some people will argue with but hey, that's diving.

First, you were probably overwieghted by your instructor at first for the simple reason to get you down without any problems. Now that you're certified you should play with the weights and start skimming them down a few pounds at a time until you can get to a weight that is comfortable for you.

Second, don't allow anyone to tell you "you are wearing too much wieght". I think this is complete BS. You wear whatever you are comfortable with, can control your bouancy, and make a safe controlled ascent at the end of your dive. That said, you are wearing too much wieght.

A good rule of thumb to start with is 10% of your body weight +3lbs. So 240lb guy should wear 24+3=27lbs. What ever you decide to do though it is probably best to start a little heavy, especially being a new diver using AL80's. They get bouyant at the end of the dive and until you've got a few dives under your belt my advice would be to be a bit heavy until until you figure out what you need at the end of your dive for wieght, not at the begining of you dive. The best way to do this I think is when you're hovering at 15' for your safety stop start thingking about how much, or how little air is in your BC; picture a ballon and how much air it has in it. You shouldn't need much air at all at the end of your dive using AL80's to hover comfortably at 15' at the end of your dive.

Now the drysuit question, this people will probably disagree with me but hey, diving is what you are comfortable with and what you can do/handle, especially in a crisis.

I do not use my drysuit for bouancy and I never will. I think it vents slow, and if you ever get inverted and start up you have to barrel role and pop the neck-seal which for me is a unappealing option.

I use my BC for bouancy and add just enough air to my drysuit to get rid of the squeeze. It dumps air a lot faster than my drysuit if I need to do it without positioning my shoulder/arm to vent, it allows me to also vent when I'm inverted quite easily.

The problem with this most will argue is that it's too complicated. You're doing too many things to control your bounacy and in that single argument they will probably be correct. But, I've been diving in my drysuit this way a long time and I'm quite confident and proficient in how I control my bounacy. I add air to drysuit to about 30' or so to slow my descent and get rid of the suqueze and after that I start using my BC. If at some point I need air to my suit for suqeeze or warmth beyond that, than I put a squirt in my suit and tug on my inflator for a split second to vent a bit of air. At the end of my dive as I'm approaching 30' I just dump the air in my BC, a quick tug on the inflator and it's empty and 99% of the time I'm perfectly neutral at that point having to do very little to my drysuit to control my bouancy.

I also work with a lot of students so I do things a bit differently than most divers. I wear too much wieght, about an extra 12lbs in case I need to grab a student startring to go up a bit. This helps me control them as well as myself, and using my BC for bouancy also helps me do this better. With a quick tug on my inflator in a horizontal siwmming position all the air is gone, no turning upright, no shoulder role to get my vent up, the air is gone and the student and I are both undercontrol without a lot of difficulty.

Now a lot of people will argue with what I've said but here's the bottom line with diving. Fit and comfort are #1 and #2 when you dive with your equipment. You do what fit's you the best and you are the most comfortable with, not me or anyone else. You're a new diver, play with your setup some every few dives to figure out what you like. Just do me and you a favor, play with one thing at a time. Don't go making a bunch of adjustments to your wieghts, your gear, how you wear it and what you're wearing. Do one thing at a time, start with the wieghts and go from there. You'll need to tweak it as you go but don't do everything at once.

Good Luck and happy diving!

 

[TSandM]

You've gotten some great advice from the people above, but I want to address something nobody's really talked about yet: You say that you were bumping along the bottom because you were overweighted. That's actually not true. You were bumping along the bottom because you were not neutral.

Being overweighted makes things difficult because of the amount of air you have to add to your BC and/or suit to BECOME neutral. That amount of air makes the BC bulky and hard to swim through the water, and makes it much more unstable with small depth changes. But it is QUITE possible to become neutral when overweighted. Technical divers who carry large amounts of gas, and extra tanks, are extremely negative when they descend, but they can become neutral and dive comfortably.

There are a number of things that contribute to the tendency of new divers to do the entire dive negative. One is the fear that, if they add enough air to become neutral, they will begin to ascend. (I had this problem in spades at the beginning!) Another is the attitude that the diver has assumed in the water. If the diver is in a severely feet-down attitude, then every kick he does drives him both forward and UPWARD; the only way to avoid ascending, then, is to be negative. Redistributing weight so that the diver can remain horizontal really helps with this.

Finally, let me just commiserate a bit. Learning to dive in our cold waters is FAR more difficult than doing it in the tropics. Life in a drysuit is more complicated and challenging than in a wetsuit, and it does take time and practice to learn to feel the cues that tell you you need to begin venting, so that you don't get behind the buoyancy curve. During the time you are working with this, keeping the minimum air in the drysuit you can and remain reasonably comfortable really does help. Once you are more facile with the dry suit, you can add a bit more air to improve your comfort and warmth. (And then you can buy a new dry suit and feel like a klutz all over again, until you get the venting sorted out . . . )

 

[Ber Rabbit]

My buddy and I recently got certified through our uni's dive-club. We've done 8 open-water dives total in cold water (Vancouver), wearing shell-suits for 7 of them. The issue we've both been having is about weight. I'm about 135 lbs, he's maybe 150 lbs. I wore 38 lbs last dive, he wore 40 lbs, which surprised the divemasters who took us out on the club-dive, considering we're not big guys and that (apparently) is a lot of weight.

Like the others have said, a lot of factors affect how much weight you carry. Basically you trade weight for warmth, the more air you keep in the suit and the thicker your undergarments the more lead you need to carry to compensate. First of all make sure you have a suit that FITS! I can tell you from personal experience that a suit that is a "close enough" fit will frustrate you to the point of wanting to dive naked in cold water rather than fight with the thing. Diving should be fun, you will have more fun wet than in an ill-fitting drysuit. You sound like you aren't happy using the drysuit for buoyancy so do your next dive with the BC for buoyancy, I bet you will be much happier. Leave your vent in the open position (unscrewed) so the suit can vent as it needs to. Dump all the air out of it on the surface and burp it again when you get in the water. Drop to 20 feet, notice what the suit feels like. This is a good amount of squeeze to maintain throughout your dive so as you go deeper add just enough air to the suit to maintain that "feel." If you are getting cold you will want a bit more air but again, not too much more.

When you are ascending you NEED to be aware of what the suit feels like. There is an "uh oh" moment when you feel the suit stop squeezing you as tightly, this is when you need to raise your arm and dump the suit because shortly afterward you will ascend. Personally when I'm ascending I dump some air from my bc first so I'm a little negative then I swim to the shallower depth dumping the drysuit as needed. If I'm using an upline for ascent I completely dump the bc before ascending and again can control my ascent speed by kicking and dumping the drysuit as needed. Once you get the hang of that you don't need to kick any more you can actually maintain your ascent rate by dumping air.

I am about the same size as you and carry 28-32 pounds depending on what I wear under my suit. My husband is over 200 pounds and carries less lead than I do--go figure but I'm wearing heavier undies than he is because I get cold easier.

The thing is, we've both had trouble with keeping bouyant, and will often begin to float to the surface when around 20 ft after getting down to about 1200 psi

This is the hardest place to control a drysuit believe it or not. I can tell you if I'm at 17 or 18 feet because the characteristics of my suit are completely different at that close interval. I'm at 17 feet and I feel like I want to shoot to the surface, 18 feet and I feel like I'm going to plummet. Mastery begins in the shallows so if you can control a finicky drysuit in 20 feet of water you will be fine in deeper water, Boyle's Law will see to that

So far we've both kept relatively shallow for our first few dives, but I'd like to start getting down to 50 or 60 ft now that I'm getting more comfortable underwater. Still, I have trouble staying bouyant, and am often afraid to releave the squeeze of my shellsuit by inflating air into it in the fear that it won't vent fast enough as I slowly surface, causing me to shoot up and get bent. How real is this concern?

Take it from someone who had a REALLY hard time learning to dive in a drysuit, it's easy to end up afraid of the equipment. Some people just click with their suit and dive great out of the box, others of us struggle for a while before the click finally happens. I struggled for 75 dives and have had my share of uncontrolled ascents because the drysuit wouldn't dump until I was 4 or 5 feet from the surface. One of those ascents was from 50 feet, another one from 100 feet and it is scary. I lost all faith in my suit after that 100 foot ascent, I'd even had the valve pressure tested and all had come back fine prior to that incident so that enhanced my fear of the suit. I bought another suit just like it but cut "thinner" so it fit better and I have been a happy, in-control drysuit diver ever since. I was even able to give up the ankle weights!
Ber :lilbunny:

 

[Bismark]

I live on Vancouver Island. PM me and I will connect you with some people in Vancouver (close to the Uni) who will help.

Cheers,

 

[Doc Intrepid]

I live on Vancouver Island. PM me and I will connect you with some people in Vancouver (close to the Uni) who will help.

Cheers,

I suggest you take Bismark up on his offer...the very best way to learn this stuff is in the water with a mentor who has their act together... FWIW...