Starting Drysuit Class

[Mike126]

I've decided to take the PADI drysuit class in a couple of weeks. I have a few questions.

Last weekend I was at the shop trying on the rental drysuits to use during the class. Given these are rentals I was not expecting a perfect fit but the one that was wearable for be (Bare Nexgen XL Tall) had a latex neck seal that was just a little too big. It was not fitting tight enough. The shop owner recommeded that I try this suit during the pool dives and then use the owners suit (same size Bare Trilam) that should have a better fitting seal for my OW dives. She mentioned that the hood may help some to keep the leaks to a minimum.

I was wondering if taking a new latex seal and laying it over the existing drysuits neck seal once I have it on would work to seal my neck. Sort of like wearing a neck gator.

Also, in reading the PADI book they seem to recommend using the DS to manage bouyancy while diving instead of your BCD. Is this the preferred method or should I only inflate just enough to reduce the squeeze and use my BCD as I normally would?


Thanks!

 

[tbone1004]

1. no, it won't work, the neck will likely still leak.... Sorry, sucks, but such is life. The hood will help to mitigate it some, but not fully. The seal doesn't have to be tight, just tight enough to keep a seal. When you crane your neck is likely when it will leak on you.

2. no, it should only be used in an emergency, use your BC as your normally would and keep enough air in the suit so you are comfortable.

 

[spoolin01]

It's a pretty expensive possible solution for one or two dives, but Apollo makes an ultra-flexible neoprene neck gaitor, the BioSeal, that will add a little diameter to your neck, and provide a smoother surface for the seal to ride on. I use it and find it improves the seal (with my folded under neoprene neck seal). I don't know if you'll find further use for it once you get your own suit - I've read here that it may hasten the degradation of latex seals.... silicone or neoprene seals, prolly not.

As a cheaper alternative, I've heard you can wrap a bunch of electrical tape around the seal end once you've got the suit on. :evil: (might be better suited as a wrist seal trick...)

 

[highspeed]

Seals can usually be replaced fairly easily, and breaking the seals is actually quite common, so the newer dry suits have quick seal replacement technology. So you may be able to just put on a smaller seal. Wouldn't rely on a hood or anything else to keep you dry. all it takes is a bit of room in that seal and it will start seeping in. By the book, you are suppose to use ONLY your dry suit to stay buoyant. But in practice people use their BCD as well... If you find your self over weighted and are too lazy to fix it you can just inflate the BCD a bit. But I personally just use my dry suit for inflation.

 

[tbone1004]

unfortunately that book couldn't be more wrong wrt using the suit for your primary buoyancy control. The bubble is much harder to control combined with a whole slew of extra problems. PADI put that in there to reduce task loading so you are only managing one bubble instead of two, but that doesn't mean it is the proper way to do it.

There should be a line in there saying something to the extent of, use your suit for buoyancy, unless you have a neoprene suit in which case you'll need your bc for some of it. There should then be another line that says something to the extent of "in tec diving you use your BCD for buoyancy control"

There is a fine line where you typically start putting more air into your suit towards the end of the dive to combat the cold, but you should still only put the amount of air into the suit that you need to stay comfortable.

Your BC serves two purposes when diving in a wetsuit, manage the weight of the air in the tank, which can't be factored in during weighting and why proper weight tests should be to either weight the diver neutral with a full tank and add the amount of air that the tank is displacing to the weight belt, i.e. weight to neutral and add 4lbs for an AL80, or do the check with a tank at 500psi and call it good. Second purpose is to compensate for the wetsuits loss of buoyancy at depth which is the other part of why you have to add air to the wing on descent, and dump air on ascent as the suit decompresses.

Conversely in a drysuit, your wing still serves two purposes, the first obviously being to compensate for the weight of the tank, but the second becomes taking over lifting responsibility in the advent of a catastrophic drysuit failure.

So, what does this mean with regards to using the drysuit for primary buoyancy control. Your drysuit is nice because it maintains the same positive buoyancy with no change at depth, which eliminates that duty for the wing, BUT if you are also compensating for the weight of the gas, then you then have to manage that bubble which is anywhere from 5-15lbs of air depending what size tank/s you're diving. Twinsets of large steel tanks can have an air shift of up to 15lbs, which is too big to manage in a drysuit. An al80 doesn't have much of a swing, so it isn't too hard to compensate for in a drysuit, which is why PADI has that in the manual. For me, I always get my drysuit where I am comfortable, usually quite squeezed, and then take the rest up with my wing and it works much better, just a slight bit more complex having to manage two bubbles.

Also most suits don't have "quick seal replacement technology" which is not something I've ever heard of..... You can get zip seals as an option on the DUI suits, and you can have rings added to any suit, but only a small handful come with them standard. I'm frankly surprised the shop hasn't put them on their rental suits if they are doing this on a regular basis, they're just as easy to put in as a normal seal, use the same latex seals, and would save a lot of headaches, and are only about $150 to put in per suit for wrists and neck if you do it yourself.....

 

[FinnMom]

These threads usually get many knowledgeable and experienced persons very strongly on both sides of the suit for buoyancy control vs. BCD/wing for buoyancy control argument. I'd say the smart money is on knowing how to use either or in case of need. try for yourself the advantages and disadvantages and decide your own opinion.

 

[highspeed]

newer suits do have seals you can literally take off and put on in a minute, no glue or anything.

 

[tbone1004]

highspeed, they really really don't. Only those with the option at purchase, or the VERY small number that come with them as standard. DUI has zip seals as standard on their newer suits, so you are correct as it relates to DUI, but this is not standard across the rest of the brands.

A select few of the premium dry suits come with the Si-Tech ring systems installed, you may very well see a lot of suits that have them installed in the Midwest because of drygloves, but as a rule, drysuits come with standard glued on seals unless you pay the extra money to have the ring systems put on which is typically about a $400 option if you order it at the time the suit is purchased, and is only an option from certain companies that work with Si-tech or have their own system, which are 4th Element, Waterproof, Whites, Santi, and I'm sure I missed a few others. The point is, that it is a $400 ish option to add these systems to the drysuit, which can be added to any drysuit, but they do not come standard.

 

[Jim Lapenta]

Not all of them. Zip type seals are usually an option that must be selected on a new suit. You might get lucky and find one with them installed to begin with but I would not count on it.

As to using the suit for buoyancy? Nope. No dry suit mfg recommends their suit be used for primary or even emergency back up buoyancy. It is an exposure suit. Period.
What some do find out after some experience is that adding enough air to offset the squeeze in some configurations is also enough to get neutral, IF THE DIVER IS PROPERLY WEIGHTED TO BEGIN WITH, but not throughout the dive. I get lucky at certain depths with this but then descending just a little deeper where the squeeze is not uncomfortable means I still use the BC for primary buoyancy.

The reason why some teach to use the suit is that they underestimate the ability and intelligence of the diver. They wrongly think that managing two inflators and deflators is too much task loading. It's not. it just requires competence and patience on the part of the instructor and the student. It's not rocket science.

As tbone stated what you end up with is too large of a bubble to manage effectively and it becomes downright dangerous. What's even worse is new dry suit divers are often over weighted to "help" them manage the new gear. Another big mistake that makes using the suit for buoyancy even harder.


At least one agency is moving away from teaching using the dry suit for buoyancy and it will be reflected in the materials for the class soon enough. Enough air to manage the squeeze, proper weight checks, the BC for buoyancy control, and your buddy, dual bladders, lift bags, or sufficient size SMB's for emergency back up.

 

[boulderjohn]

Also, in reading the PADI book they seem to recommend using the DS to manage bouyancy while diving instead of your BCD. Is this the preferred method or should I only inflate just enough to reduce the squeeze and use my BCD as I normally would?

The PADI book does not give a blanket recommendation to use the dry suit for buoyancy. If yours does, it is far outdated. The course teaches that what you use for buoyancy depends upon several factors. In two of the three cases, they suggest using the BCD for buoyancy. the primary difference is the amount of weight you need during the dive, which affects the amount of air volume you need to maintain buoyancy.

One example they give is technical diving, in which divers are usually overweighted. If I am doing technical diving, I usually have just the right amount of air in the dry suit to be comfortable, and most of my buoyancy management is done via the wing. That is what most of the people in this thread have said so far. If you wanted to be buoyant using only the suit, you would need a ridiculous amount of air in the suit, and the PADI course says that specifically.

When I am diving with a single tank, especially an AL 80, and I am properly weighted, I start the dive with no air in either device. As I descend, I add air to the dry suit to avoid a squeeze. When I do, I usually find that I don't need much air in the BCD, if any. In that case, I still don't have more air in the suit than I need to avoid a squeeze, but I am primarily using the suit to adjust buoyancy. If you have a comfortable suit and a significant amount of air in your wing, there is a good chance you are overweighted.

Even when technical diving, though, I will sometimes make minor buoyancy adjustments with the suit. It depends upon the situation. Sometimes a little jab to the chest is just the right thing. I also do it sometimes when I am doing decompression stops. At the end of the stop, a little jab while inhaling gets me drifting upward, and a little lift of the arm 10 feet later is an easy way to stop that drift.