Drysuit undergarment changes and weighing.

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Kevin A.

Registered
Messages
25
Reaction score
12
Location
Malta
# of dives
500 - 999
Hi folks,

Based on your personal experience, can anyone provide a guesstimates as to how much extra lbs/kg I should expect to add when adding thicker mid-layers (Bare SB system mid-layer) to the thin base layers (Bare SB system base-layer) I usually use?

Some info; diving in a compressed neoprene DS, I require 17lbs/7.6kg extra weight using thin undergarments.

Last year, diving a BP/W OC config; I had put on an extra 11lbs/5kg which seemed a lot.


Thanks
 
Size and compression matter.... however this last weekend. I added my mid layer. I also added 3 lbs of weight. I was a tad bit heavy. But less then 1 lb. so elected for the added weight then too light. This was in fresh water using bare base layer and adding the mid layer full jumpsuit.
 
When diving with thin fleece under suit (fleece pants and fleece pullover top) I used between 6-8kg of lead...I can go as low as 6 but I have to have less air in the suit at the end of the dive to remain neutral at my safety stop...having 7-8kg is much better margin and allows me to put more air in the suit for warmth at shallower depth due to the greater change in buoyancy at 10m and above...buoyancy is due to added air in my drysuit does not seem to be a problem below 12-15 meters and I can add as much air as I need to be comfortable without adverse affect on my ability to maintain position in the water column.

When diving a thicker undersuit (I used a Fusion Thermal), I need 10-12kgs of lead. I can go as low as 8 or 9 but at 8 I found I need to hang onto a rock if my safety stop is static....if I am swimming, I can maintain depth during the safety stop depth but have to focus on staying down and can't multi-task as I wish to so shooting a DSMB or assisting with an issue would be problematic due to lack of lead. At 9kg I would be on the border of being able to stay down at that depth, and at 10kg I have no issues with buoyancy but will need to suffer some chill due to not having much air in the suit. With 11-12kg I again have enough weight to manage my buoyancy while also being able to maintain air in the suit for comfort.

My configuration is a BP/W without any padding (except the sleeve on the crotch strap), and Fusion Bullet dry suit (nylon with a 1mm neoprene over-skin).

The idea, at least in my head, is to have a balance between control and comfort....there is no formula for that as the amount of air one person needs to be comfortable is different than the amount another person needs. Another factor is how compressed the undergarment is....when new fleece undergarments tend to be thick and have a lot of loft, but with washing and use they tend to pack down and become matted which often translates to them trapping less air...this means that one may not need as much lead to get/stay down but it may also mean that more air is required to manage comfort/warmth in the suit.

I think the best solution is to note in a log book the configuration of the exposure suit after every dive and annotate if the amount of lead was adequate. Then, at some point, you can reach back to this information to plan what you want to wear for the temperature and how much lead you will need to comfortably/safely manage.

I hope that helps.

-Z
 
Hi folks,

Based on your personal experience, can anyone provide a guesstimates as to how much extra lbs/kg I should expect to add when adding thicker mid-layers (Bare SB system mid-layer) to the thin base layers (Bare SB system base-layer) I usually use?

Some info; diving in a compressed neoprene DS, I require 17lbs/7.6kg extra weight using thin undergarments.

Last year, diving a BP/W OC config; I had put on an extra 11lbs/5kg which seemed a lot.


Thanks

Kevin...

In an attempt to answer your question...I'll explain my dry-suit system...and what I do...

I have a custom built DUI CF-200 Signature suit... size...probably best described as a ''Large-Tall''...if you're unfamiliar with this suit...it is manufactured from DUI's proprietary ''crushed neoprene''...neoprene neck and wrist seals...and soft feet...

The suit has a telescopic waist...with integrated crotch strap...and fully adjustable suspenders...the suit fits like a glove with absolutely no ''over- bulk''...this is the primary reason the system works so well...

Undergarment consists of two piece T-Max Heat suit and I layer up the top with a cotton ''thermal knit'' crew shirt...my socks are also T-Max Heat...

I regularly dive in Ontario Great Lakes water that is only a few degrees above freezing in mid July...and often dive in late November/early December...weather and conditions permitting...

This system combination keeps me nice and warm...and very comfortable...

As far as ballast...I wear no more than I would wear with a 7 mm wet suit...

It's not the dry-suit and undergarment loft that's keeping you positively buoyant...it's air trapped and not properly evacuated in the ''over-bulk''...

My rebreather is light...fully charged...less tanks...under 30 pounds...with tanks 50 pounds...for ballast I wear two six...and two four pound shot packs...20 pounds total...I prefer shot packs as they're not damaging to my integrated pocket system...and they mold to contours...

As I descend...my wing is empty...neutrality primarily comes from my counter-lungs...at depth I add a little gas to the suit...not the wing...and prior to my ascent...I exhaust the suit and ascend with the only buoyancy gas being the gas in my counter-lungs...and when reaching the surface...I then inflate my wing...

Spend a little more time evacuating trapped air...pre-dive...you'll find there is a significant difference...and you can start using the gas in your tank for breathing instead of filling and exhausting your BCD...as well as dropping a good portion of your current ballast load...

Hope this narrative helps...takes a little practice...you'll get it...and remember...more ballast is ''not'' the solution to the problem...

Dive Safe...

Warren...
 
Just like Zef, I note in my dive log what I was diving and how much weight I was using.
Adding an extra layer to my base ware (mostly wicking layer) will add #2.

Interesting....I am using underarmor polypro type garments as a base layer, but I have done a couple of dives without the bottoms...I have not found it to materially impact the weight I need....I wonder if it is because of a need to overcome the inherent buoyancy in the neoprene over-skin of my drysuit.

-Z
 
Thanks for the input all,

Ok, let me expand on the detail a bit.. I'm diving the 2mm hyper compressed Bare XCS2 Tech dry. This is a stretchy neoprene DS and very properly sized. So there's zero overlap with a perfect wetsuit like fit.

Here a DS is not an absolute necessity, sea surface temperature lowest is only about 15°C (59°F) in winter. So most of the time I'm just in my thinnest base layers for warmer months, and taking real measures to avoid pre-dive heat exhaustion in the peak of summer. I know most would ask wtf is he using a DS for.. but that's another topic. I'm just ready to accept the cons for I love some of the pros of DS diving.

I just switched from OC to CC earlier this year and so my rig is completely different. In OC I was used to jumping in slightly overweight as I was weighted for very low gas on all tanks. In CC I'm weighted right throughout the dive, so the wing is mostly empty and not much used underwater. A little gas in the DS to loft and get the right trim will typically mean I'm neutral.

The problem (I think?) with this thick material (Bare SB mid-layer) I rarely use is that it traps a lot of gas within (floaty?). A matter of ratio between material weight to material void to trap air.

My intention was to get some feedback before applying the seemingly massive change I had applied last year diving OC. I'm still awaiting a break of good weather over some weekend to sort this out. It's going to be lots of drop weights me thinks.
 
I am in similar situation as a new rb diver. Do you have previous OC experience with thicker ds undergarments? They are floaty, and make gas release difficult.

It's not the dry-suit and undergarment loft that's keeping you positively buoyant...it's air trapped and not properly evacuated in the ''over-bulk''...

This is true. Thick undergarments release air really slow, and make difficult to empty your ds completely. For rb buoyancy control you must have gas that you can dump relatively fast. To completely evacuate air with bulky garments requires quite a lot of work and anticipation during ascents. Thus your optimal weighting may be a tad heavier than what is the absolute minimum required to submerge with thoroughly evacuated suit and minimum loop volume. It just is easier to dive with thin garments.
I always do a checkout dive after making any significant changes to my undergarment configuration, including adding just one relatively thin layer.
 
As I said earlier, I don't dive thick undergarments very often. It's just in the coldest months when I get a chance to dip between bouts of bad weather.

Yes, this is the 'before' the checkout dive.
 
As I said earlier, I don't dive thick undergarments very often. It's just in the coldest months when I get a chance to dip between bouts of bad weather.

Yes, this is the 'before' the checkout dive.

Hey Kevin...

Not meaning to use the term ''Thinsulate'' because it's a brand name...but there are lots of ''thin'' undergarment/underwear combinations available now that make these ''early generation'' snowmobile type undergarment suits obsolete...

As well as the micro-fiber products there are also some Merino wool one and two piece sets available now...my three piece + socks set...when folded up will fit in a plastic grocery store bag with room to spare...

More bulk/loft no longer means more warmth...talk to the avid out-door winter sports people...they're out in much colder conditions than we are...

Best...

Warren
 
https://www.shearwater.com/products/perdix-ai/

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