Why Thinsulate?

[Mo2vation]

Here's the scoop:

* I have the grey DUI Polartec undies, label rated 45 - 60 degrees.

* I just acquired in a package deal DUI Thinsulate 200 undies, label rated 50 - 60 degrees.

Seems to me the DUI gray polartech is a little thicker (as its new, and is two layer) and its very stretchy - I like it. Been diving this stuff for years.

The Thinsulate seems "thinner" - but it doesn't stretch. However, it is "slicker" against the inside of my suit, etc. But there is the whole maintenance thing (washing, etc.)

Question: Is there an advantage to be realized, one over the other, when they're both essentially rated to my general diving temperatures? I understand Thinsulate will still keep me warm is I flood, but I don't deco dive so that's really lost on me.

Just wondering if I'm missing a critical advantage, as I've only been diving the Polartec and never dived anything else.

For example, does Thinsulate generally require more gas or less gas, which will translate to more weight / less weight.

Thanks

Ken
Drysuit Undie N00b

 

[jerryn]

I was using 400g thinsulate and had a neck leak in 39 degree water. I felt real bad on the way in, but there was not so much that I had to abort the dive and I stayed warm during the dive. After that, I retired all of my undergarmets and went to thinsulate.

I dive my dry suit shrinkwrapped and do not find that I need any additional air with the thinsulate. I am using less than with fleece and cannot speak to polar tec.

Jerry

 

[Doc Intrepid]

Hey Ken,

The issue has lots of factors, but boils down to two or three basic functions.

Thermal protection, especially in the event of a suit failure (and if you don't look at long deco hangs, then you have less of a potential exposure than a guy with a flooded suit and 45 minutes of deco obligation to perform);

Flexibility - e.g. ability to reach your valves for valve drills, as well as reach around to cut yourself out of a net, reach back behind you for whatever reason, etc.; and

Amount of gas in the suit. Gas in the suit contributes to challenges with trim and bouyancy.

Undergarments generally work in one of two ways, either they reflect body heat back inwards - using thinsulate/mylar/aluminum membrane panels, for example, or else they create a dead air space. The thicker the air space, the more effective the insulating ability. Obviously however, the larger the air space underwater the more problematic.

Undies such as the weezle are wicked warm. But since the insulation mechanism involves airspace and fibers, there is a degree of loft required to achieve optimal thermal efficiency/effectiveness. Loft requires gas in the suit. The primary difference with undies like the weezle are that they require more weight than either polarfleece or thinsulate undies. More weight to offset the slightly higher bouyancy you experience from the additional gas in your drysuit. Weezles don't stretch much, so if you dive your drysuit extremely tight its possible to have difficulty reaching back behind your head to do the valve drills.

Stretch thinsulate, in contrast, doesn't require loft for thermal efficiency/effectiveness - so is (according to conventional wisdom) 'warmer without the excess gas in the suit'. Generally speaking, thinsulate doesn't require excess gas, so requires less weight on your rig.

Less gas in the suit means less gas giving you problems with bouyancy and trim, allowing you to dive a tighter suit while still being able to reach your valves, etc. - higher degree of personal flexibility.

There is also an anecdotal argument that underwear which works based on reflected heat - e.g. thinsulate, will continue to provide some thermal protection if the suit floods, whereas undergarments that use loft/airspace will lose any thermal protective ability. I simply don't have any data or experience to comment on that either way.

All else being held equal, stretch thinsulate undergarments ostensibly offer you increased flexibility, high levels of efficient termal protection, and continued effectiveness should your suit leak. Moreover, they offer you these benefits while still allowing you to dive a tight suit - ergo, no added problems with trim and bouyancy, as compared to undergarments that require loft for optimal performance.

But none of this has really been proven (to my satisfaction) yet, empirically or otherwise. What I know from my own diving is that with water temps in the high 30s, Weezles are real warm. I've not yet played with my 200 gr stretch thinsulate yet to really be able to compare and contrast, but to date - even with the problems that loft brings to the table, in extremely cold water I suspect that loft may ultimately be warmer than the thinsulate. It really comes down to what the water temps are where you're diving, and your individual, unique susceptibility to cold.

(If your suit floods in extremely cold water, I'm not convinced that either one will keep you toasty...)

FWIW,

Doc

 

[JeffG]

For example, does Thinsulate generally require more gas or less gas, which will translate to more weight / less weight.

It requires less gas. And that gas (thats is being held by the fibers) is very hard to displace with water, which is why it works better when flooded.

 

[Derek S]

Hey Ken,

I too myself dive a DUI Polartech fleece undergarment with my OS Systems drysuit. It works good for me, but I am a pretty big boy who stays warm well into the winter. Once I slim back down to my fighting weight, I'll be getting a new TLS350 and a set of 400gm thinsulate undies.

That being said, everything is YMMV. You might get colder than I do and need more gas to offset the temperature changes. You might not like the squeeze and want more gas in the suit to fix that as well. I usually keep my suit pretty tight, as long as no vital organs are in jeopardy from the squeeze (yes those ones), I lay off the inflator as much as I can.

Long story short, Thinsulate keeps it's thermal insulation even if the suit is completely flooded. Can't say the same for Fleece or Polartech.

Again, YMMV. :14:

 

[JeffG]

You might get colder than I do and need more gas to offset the temperature changes. You might not like the squeeze and want more gas in the suit to fix that as well.

Once enough gas has been added to the suit to give the underwear its full loft, any additional gas has no thermal benefit.

 

[jonnythan]

Disclaimer: I have used 300-weight fleece and 200-gram Thinsulate.

What do you want out of undies?

1) Keep you warm when wet.
2) Not require a ton of air [buoyancy] to do so.
3) Give you enough flexibility to complete the dive.

Let's take them point by point, because Thinsulate is the best on 2 out of the 3.

1) Thinsulate maintains its warmth better than any other insulation when submerged. Period. It will pick up less water and maintain the highest percentage of its original warmth compared to any other insulation. Fleece is particularly bad in this regard. When underwater it will become completely saturated and very cold very quickly. BTDT. Fleece is freezing-butt cold when wet. Additionally, fleece is simply not as warm to begin with when compressed.

2) Thinsulate has more warmth per unit thickness/loft than fleece or the Weezle stuff, so there's less weight required and less air you have to keep in the drysuit.

3) Fleece certainly has the edge here, I think, but DC did a great job of combining traditional Thinsulate with Stretch Thinsulate to provide a suit that gives a level of flexibility with minimal bulk that is just fantastic.

 

[Mo2vation]

I dive in 49 - 65 water year round - the cold end in winter, the warm end in summer.

I don't deco dive - so a flood simply meand a shorter dive.

I tried it on - and although its not a stretch Thinsulate, I don't see a problem with flexibility. I'm a stock medium, and the 350 is cut pretty big... so getting around in it is no issue.

I'm thinking I will personally not realize a benefit that will offset the care demands (or lack thereof - ie: dirty diving...ew) of Thinsulate. I suspected I'd use less gas, as there is no loft requirement to its warmth. I dunno.

I need to noodle on this a bit. It does fit closer, and is easier to get on and off. I may just flip it.

Thanks all.

Ken

 

[jonnythan]

Fleece sounds perfectly sufficient for your diving.

Take both in the water and see which you like better. Wasn't that easy?

 

[JeffG]

Fleece sounds perfectly sufficient for your diving.

Take both in the water and see which you like better. Wasn't that easy?

Well, after diving lots of flooded drysuits, you will never get me out of my 400 gm's undies (but that makes them a little on the ripe side )