Santi BZ400X 'Extreme' thermal undersuit

I must be getting soft in my old age....five years ago no hood or gloves at any time of the year, then I started with a hood, then gloves, then dry gloves and now this a new undersuit as the 4th Element kit doesn't seem to be 'cutting it' in the winter!

It was after a particularly cold dive at St Abbs that I thought, 'no more', I was a shivering bloody wreck despite multi-layering the 4th Element stuff and decided to look for a new winter undersuit.

After spending a little time looking at various options I went for this bit of kit from Santi, initially for a couple of reasons:-

A total density of thermal insulation at around 420 mg/m2 would mean that it would tick the box regards thermal insulation; and

The style of manufacture with the suit being quilted would mean that the insulation would not migrate about as a relatively well fitting dry-suit was put on, I was concerned that the bulkier suits would be fine under a 'large' membrane suit but might be a bit problematic when pulling on my o'three suit.

I know that there are cheaper options on the market, with this suit retailing at a RRP £350 but actually closer to £299 from most stockists but it is extremely well made and should last a long time. So what do you get on-top of a standard undersuit? Well quite a few of the features are the type where you go 'aaaaaaah what a good idea'.....

There is a tailored hole complete with grommet to allow you to wire in an electric vest, useful if you really feel the cold or you are planning on some dives with long hang times doing deco

There are a couple of flaps built in at 'hip' level allowing you to plumb in a pee valve, and with one either side it accomodates guys who dress to the left or right!

Braces, ahh yes there are braces and these are the only feature that are a negative, or relative negative. The first time I used the suit I went 'commando' and it was certainly warm enough but there was a big problem, the braces are quite rough, on both sides, and after two shortish dives of just under an hour duration for both I had a case of joggers nipple so if you are using this suit you really do need to wear a vest to prevent this painful occurence! I wore a light vest on the second day and had no issues.

And yes a 'tailored fit' which looks ok compared to some of the shapeless options, so great for all of your poseurs out there!

I did appreciate that my weightings would change when wearing this suit so had a 'cheeky' check dive before going on real dives where I may need to do deco and as such it would be very important not to be 'floaty'. During this check dive I found that I would need an additional 4kg (four!) to keep me at an acceptable level, now that is quite an increase in weight and does impact on your general 'agility' when out of the water so please be aware that if you are going from two piece protection systems to this suit you will need a significant amount of jiggery pokery to get you back to your usual diving attitude.

I must say that during a weekends diving I was very warm whilst spending up to an hour in this suit, even at water temperatures around 70C... and then going in for another hour after a surface interval in temperatures barely above freezing point. Well I say that I was warm, my body was but my feet started getting a bit chilly but that is my fault as these were proteced only by normal socks and a neoprene boot inside rock boots........I can feel a need for thermal socks in winter 2018/19!

Richies rating 9/10; great piece of kit, a bit more expensive than some of the options but you do get what you pay for! My only down rating would be based on rough braces and the associated joggers nipple but all you need to do is wear a thin t-shirt.


Recommended suppliers

Latest Photographs