Dorota & Wojtek(Offline)

We do get cold…
From the time we started to live in Africa, every temperature that is lower then 20oC seams to be a begining of a winter for us. This year we came back in winter to Europe to do some cold water dives, so we had to find a right undergourment. Undergourment that would not restrict our movements (like reaching the valves or putting the gear in the water), and at the same time that would give us maximum warmth comfort without being excessively baggy.


Here is the undergourment we have chosen:

SANTI BZ400.
The undergourment in current version comes from a modified model known as "BZ400-Andrew". It is designed for divers with high expectations regarding warmth comfort while long dives, like technical dioves, uw photo-video sessions or done simply in very cold conditions. So far the advertisemenst – but how it is in reality?

Before we start to discuss the structure of the undergourment it is good to mention that the main problem for dive undergourment producers is the lack of stretchability of the Thinsulate (the material that keeps us warm). To be able to reach valves without problems we need quite a lot of excess material – oposite to undergourments from stretchable material.
This couses that the undergourment tends to be baggy, and there is quite a problem with fitting it into a dry suit. And even we manage to fit it - the manouverability is just a memory.

How the problem was solved with BZ400 we will try to explain in a moment.

The invitation for testing and modifications came from Tomek Stachura – the owner of SANTI. The main goal of the whole modification action was to keep the maximum of manouverability along with minimum volume of the undergourment and all this with highest possible warmth comfort.

And here are the results:

General front view :




Undergourment consists of three layers:
-Pertex – outer layer
-Thinsulate BZ400 – „warming” layer
-Mikropolar – inner leyer


We have resigned (for our personal undergourments) from pockets on hips – there are standard in BZ400. We have left only the chest pocket equipped in zipper.


Back general view:



The trimming around the neck can have two options:
- with mandarin collar for divers usung latex neck seals
-without the collar for divers using the neaopen neck seals. We have tested this version so few more information about this solution:

Neopren neck seal creates two layers of neopren on the neck, additional layer is created by a hood – that is why we did not want the collar, because in our opinion it can restrict haed movement to the back. And here how it looks like:




Under the zipper on its whole lenght is a wide binding that gets wider closer to top. It keeps the air from escaping thru the zipper.



The volume of the torso was minimized but still alowing full range of movements needed for operations like valve skills.

Here is a test of „side line”. The ribbing around the waist is done with Thinsulate CS150.





Reaching behind with both arms is in reality a test for how the sleeves in the undergourmens are cut and how it fits in... the butt J






Great manouverability with one arm was achieved by modification of the cut style and by partly removing the Thisnlulate from the inner side of an elbow. Otherwise there would be a big roll of undergourment that hinders the back reaching.





Take also a closer look at the way the sleeve is attached to the schoulder area – this way we prevent the sleeve to slide down after putting it into the dry suit.






The ribbing under the arm gives almost unrestricted manouverability of the elbow and acts as “venting part” – from this part the air vents most easly into the suit and to the dump valve.







The way the sleeves are ended alows them to dry fast (most common leaks appear around the wrist seals) and additionaly it doesn’t excessively fill the sleeve of the dry suit






The changes were also introduced in the way the legs were done.
When we have taken under consideraton the technique of swimming of cave and wreck divers, and also the progression of swiming styles in the recreational diving (shins up), we decided also to remove part of the Thisnulate from the inner side of the knee area. Also the way the legs are cut around the knees is changed so that they are a bit “stuffed” to the front.






The leg of the undergourment bends easily while bending the knee.






What become very importand is that even thou we gained much manouverability in the legs we got rid of the baggy legs. In this way the undergourment can be used in dry suits with narrow legs.






Also the ankle part is very flexible and it is not resticting the movements of your feet.






The legs of the undergourment are stabilized by a wide rubber ribbing.





This kind of “endings” in the legs prevents the “puffy legs effect” .






The inner of the undergourment is equipped with suspenders – but this are optional.





In our opinion it is worth to have suspenders in all types of undergourments. There are two reasons: one is that the suspenders hold the thing in proper place – especially the crotch area (it is not sliding down restricting the leg movement). And the other reason is that between the dives you can take off the torso part (what might be importand for divers making few dives in a raw – instructors – and also in areas that are not so extremely coldJ)





And now few memories from our dives in BZ 400

It turned out that if the dives are not longer then 60 minutes in water with 5-7 degrees, the undergourment conected with termoactive underwear, fulfils the expectations. When the dives were up to 100 minutes and more in water of 5 degrees the case was a bit different. The warmth comfort was a bit less in the second half of the dive, what was especially noticable while stationary deco.

A solution to this problem was a functional vest from Thinsulte BZ200.






Its construction resambles a “bullet proof” vest – you put it from top, it has the sides free with some rubber ribbing.






In the back the Thinsulate covers the buttocks and the lower part of the back.





In front the vest is hold in place by a wide velcro and a rubber ribbing that goes thru the crotch area.





The way it is done doesn’t influance the maneouverablity, and also in this sense it is not interfearing with the main undergourment.





In such combinations we have done several dozen dives from 60 to over 120 minutes in water with 5-7 degrees. When we started to use the Thisnulate vest the subjective feeling of being more warm was about 30% then using only the undergourment. The vest needs about 1kg more weight.


An interesting experience was a failure of a dump valve. The undergourment was flodded from arm to troso, and leg on the same side that the valve is situated. From the first moment there was a feeling of having a “wet” undergourment, but the coolness appeared much later and slower that we expected. After the dive we could literally wring the whole undergourment.
Of course a undergourment from Thinsulate is not a remedy to cold water and flooded dry suit, but it evidently reducess the cooling effect in such conditions.


Below a GUE DIR Fundamentals class using this type of undergourment::








What is a Thinsulate BZ400?

Thisulate used by SANTI is produced by well known company called 3M. Thinsulate is a tangle of mikro-pipes that keeps-in big amounts of gases, what gives great insulating effect.


"BZ" means a Thinsulate with higher grade of compression and bigger strenght to crosswise tension (the Thinsulate itself in the most simple version is very delicate). "400" – means the density of Thinsulate – in this caseL 400g per square meter.
CS150 means “normal” Thisnulate with density of 150g per square meter.

* * *

In our opinion BZ400 undergourment is an interesting solution for demanding divers. When we take under cinsideration that all are custom made, we can get an undergourment that we realy want. The high quality of used materials connected with experience of SANT owner – Tomek (who is a experianced wreck diver) was appreciated by many divers seeking a way to warm divingJ









If any of you got so far – we trully admireJ
Still too little? – then check here CDS40 SANTI undergourment for dry suits - equipment test

We have also noticed that some people forgett about a propper undergourment fitting, and they stay only with sending thru the measurements to the producer. But the way the measurements are done is not always the best way. When you want to check how to fitt a undergourmet (and the rules are the same as while fitting a dry suit) – check here How to fit a dry suit... also.



PS.
The individual shown on most of the pictures is 180cm high and weights 85kg. For described undergourment he usues trilam BARE or nylon SANTI dry suits and steel dubles 2x12l. In full configuration he needs around 5kg of weight to be able to feel comfortable underwater.




Take care...

D&W

neilh(Offline)

Damn, and I thought my open water course in the UK in January was cold!

Nice write up and you've got me interested

Mike(Offline)

Hi,

I met Tomek at the "Boot" in Düsseldorf. The Santi is really an impressive suit with a lot of details to be mentioned. I am looking forward to receiving mine.

__________________
Dr. Jekyll & Mr. Mike

www.tauchcenter-rostock.de
www.Dive-Gear.de
Halcyon, DUI, Apeks, X-Scooter, BtS, Santi, ...

Michael-Fisch(Offline)

Looks interesting, but I don't know if it will be warmer than my Exotherm leggings socks top and vest combo coupled with Weezle Extreme+.
That has been keeping me comfortable during scooter dives in 4° water for up to 150 minutes. If it is better, I'll kill to get one though!!

Michael

Aapeli(Offline)

Hi Mike,

Same here, bought both the Enduro & the undersuit, oughta receive it by Feb 28th....cannot wait

Keiron(Offline)

I've got a 400BZ on order, but one thing was concerning me and an email to Marcin has so far gone unanswered.

It was concerning the ribbing at waist and armpits, now at least from the OP very informative post I know that it's Thinsulate 150, and not just simple elastic material. However, the armpits and waist are one of the major areas of heat loss after the head, so is the heat retention capabilities of this undergarment being severely compromised by the need for flexibility. Also, the backs of the knees are again another area of high heat loss and losing insulation here as in the OP post can't be good?

I realise there is a compromise to be made, but has this rather important part (in my mind) been overlooked? All the primary areas where major blood vessels are close to the surface seem to have little insulation?

Not relevant in the grand scheme of things? Someone put my mind at rest before I hand over my hard-earned! I don't have access to a DUI400g what is DUI's solution for this problem? No insulation or excess material? With the sudden large increase of price of the Santi it's not that far off a stock DUI which seems to be about my size.

A-M(Offline)

Nice, so we can see it in Hemmoor :-))

Aapeli(Offline)

Sure thing, just lemme have a go at it first

Aaaagth :-( delay in delivery...won't get these until the 2nd weekend of March, so no fiddling/drooling over the new suit in Hemmoor

Hybrid(Offline)

I've got a BZ200 - which I've dived for a year, and it is almost too hot for the conditions I dive in. This summer(20degrees) I've been diving either wet for shorter dives or in my drysuit with minimal undergarments for long hangs.

During winter here in NZ it gets down to 13 degrees C and then the BZ200 does a great job keeping me nice a warm. I was going to get the 400 but I think it would be too hot.

The built and cut of the suit was perfect and made my winter diving a joy

Dorota & Wojtek(Offline)

Thanks for the comment I was thinking a bit how I felt while diving it - and I can not recall feeling cool at those areas. Maybe it is enough material anyway - normally I have my knees and arms bent slightly, the material is "piled up" so there is a insulating layer. So maybe that is the "solution" with "compromise". Anyway - there is a thiner Thisnulate at those areas.