Dry suit weighting

[davisj]

I recently purchased a DUI TLS shell suit, which I am eagerly waiting for ;D. I used a wet suit on the Madeira last Oct, and froze !! Amazing how one can still have fun diving even though the feet are numb.

Anyway, I am trying to find out how much weight I will need to dive dry. I have a SeaQuest Balance BC, and it has a max capacity of 30lbs.

I will be diving using single aluminum 80's. In my 7mm jumpsuit I use 22lbs ( which I think is too much, but it has worked to this point ).

Will this setup work ? How much weight ?

Jeff

[Punky]

I recently got dry suit certified. I'm 5'10", 175 lbs, use Al 80 tank, have a Hunter vulcanized rubber suit w/underwear, &
Black Diamond BC. It took 34 lbs to get me under when I did
my dry suit/ice dive last month.
How much weight you need will depend on the insulation you
wear under the dry suit for warmth. The warmer the water the less insulation needed, the less weight needed

[lrmoll]

I remember when a group of us went out to Square Lake. One of the dry suit divers wore a snowmobile suit for insulation under the drysuit. He was up to 40 lbs or so and still couldn't get down ;D

[tbrown]

My goodness, just how cold is Square Lake? :o Seriously, Punky is right. With a shell suit, the weight you need is directly affected by your insolation. The more and loftier undergarmets you have, the more weight you will need. Unfortunelty, I don't know of a "magic" number to use. I started with what I used with my 7MM suit and worked down from there until I found what worked for me. Hey, look at it this way, now you have an excuse of why you HAVE to go diving! And probably several times to make sure that you have it right.

[wtdrm]

Dry suit weighting as in other types of thermal protection have to do with how comfortable you are as a diver also. I am a short fat kid. (275#) When I wear everything I need to keep warm in a drysuit I use 30#s I also usually use a steel 95. When I 1st started diving I would wear 40# and still not get down unassisted. I could probably use less but I would rather be a tad heavy for safety stops. The difference is I havee 200 more dives now than I did then.

[davisj]

wtdrm, Thanks for the feedack.

I don't quite understand the 10 lb difference between now and then, except for the possibility of using steel instead of aluminum, and also the "lung factor". I don't have 200 dives under my belt, but I can't remember a time that I had difficulty decending EXCEPT for my first( and only to this point) dive in Superior. The waves were huge and I have to admit that I was a little intimidated. I usually can exhale completely and drop like a rock, but for this dive in Superior I couldn't get myself to hold an exhale. I couldn't get under he water!

jdavis

[beeger]

With a shell drysuit, especially one like the TLS, your ballast requirements will be greatly affected by your underwear/thermo protection. What is critical is that you understand how much weight you need *and* how to distribute that weight. A while back I posted something in the "Drysuit or BC for Inflation" discussion in this forum that breaks down how to determine your ballast needs. You may find it useful.

One way you will be able to drop some weight is to move to a steel tank. The OMS/Faber steel 85 is an excellent tank for recreational dives in this area. I'm sure there are others, but this one seems particularly well suited. It is about the same size as an aluminum 80, but about 3 lbs heavier underwater. Of course, these cost more than aluminum tanks. Some shops around town do rent these, however.

The Balance is a great BC. Do you have the new style with the clips on the weight pockets, or the old with just the velcro? I would be careful putting more than about 7 lbs in each of these. While the pockets can handle up to 10 lbs each (just barely), it is very tight fit and difficult and annoying to slip into the BC. Plus, I woudn't trust the velcro with that much weight.

[Al]

I was taught to have enough weight to keep your head out of the water on inhale and go under with an exhale. This worked great until diving in Superior and I wanted that little extra air in my drysuit not just to fight off the squeeze but to keep me a little warmer. So I had to add a few more pounds. The whole point of getting a dry suit is to stay warm... However nothing is worse than being over weighted - especially when you find that anchor!

[tbrown]

Yeah, nothing like trying to pick up an anchor when you are weighted like one yourself. I think one thing about a drysuit that both wdtdrm and Al bring up (and correct me if I mis-read your posts) is that weight can also be influenced by how much air you put in your suit. I am by no means an expert, but the more comfortable I got adding the "proper" amount of air, the more weight I could drop as well. I think (for me anyway), it's just like any piece of new equipment, at first there is a learning curve, and then it becomes automatic the more dives you have on it. Just takes a little time, although I have been accused of being a slow learner.

[beeger]

Some thoughts: After watching and helping a number of people get comfortable with their first drysuit I've learned that getting comfortable with a drysuit primarily entails learning how to really get the air out of the suit while underwater (sometimes very quickly). It is likely that over the course of maybe 10-15 dives that you will find yourself dropping at least a couple pounds of weight for no other reasons than getting more comfortable draining the air in the suit.

There  is a big debate among some people around using the drysuit or BC for buoyancy control under water. Personally I think that using the drysuit as your primary buoyancy device is a bad idea for reasons already covered. There is nothing wrong, however, with maybe adding 1 or 2 lbs on some dives so you can keep a little extra air/argon in your suit, especially when you plan on not working very hard on the dive.

Sorry for the re-posting the content below, but some people emailed me offline a while back and said they found this very helpful. So I thought I would copy it over to this thread (originally found in the "BC vs Drysuit for Inflation").

"With full tank(s) determine the amount of weight you require to sink from the surface on a standard exhalation. This is the amount of weight that should be integral to your rig, distributed in such a manner that will provide for good trim in the water. Then, with almost empty tank(s), (maybe 200-300 psi) determine the amount of weight in addition to the above that you require to hover just beneath the surface (10-15 ft). This is the amount of ditchable weight that must be worn (weight belt, pockets, etc.) in addition to the integral weight. Once you have this down then consider the following factor: depending on the exposure suit being worn and the depths you will be diving to, compensation must be made for the compression of the exposure suit. This is done by figuring out how much buoyancy your *suit* loses, independent of the diver, at depth (remember your physics from OW class). The amount of buoyancy lost will equate to the amount of weight that must be moved from the integral component of your weight to the ditchable component. When diving a shell suit the buoyancy shift of the suit is not really an issue. When diving a foam neoprene wetsuit or drysuit it becomes a big issue. The thicker the suit, the bigger the potential buoyancy loss, the
more weight needs to be moved. Here's what it comes down to: The worst case scenario is that you have a BC and drysuit failure at the beginning of the dive (when your tanks are heaviest) and at max depth (when your exposure suit has compressed the most). Dropping the ditchable weight will reestablish your neutral buoyancy. And this is where ditchable weight systems that allow you to drop part OR all of your weight are really better than those that dump all your weight (like a weight belt). Given the above scenario, the shallower you are, the less weight you would have to drop. Dropping too much would actually make you overly buoyant."