I haven’t. I’d say my biggest learnings/changes over the past few years are:
-More merino or similar near the core (I use either Patagonia Capilene Air undies or a 250 weight merino)
-Dressing in a fashion to minimize any possible sweating, even if that means hopping in a 1°/34° pool to cool off in between moving gear to the water and formal gearing up.
-Upsizing boots if necessary to be able to wear two pairs of socks that loft and are not cutting off any circulation. Kind of critical: when people layer socks, they’re often of the same size and too constricting relative to the amount of motion our feet are doing and our bodies generating. In ice climbing, I can loosen boots at a belay stance. This isn’t true in a suit, so an extra foot size or upsized boots is preferable.
-I’ve grown fond of the Halo AR or the Weezle Extreme + depending on what can fit under your suit
-There’s a couple more hood manufacturers (my go to is the thickest Neo here: 11mm Hood - Fathom Dive Systems )
-The BZ400x doesn’t hold up to washes given the amount of Thinsulate it used. I’d order one of the Ukrainian full suits if I was looking in this direction. Hauberk is half or less the price of the Santi and has the option for two fully redundant sets of panels.
-I’ve trimmed another two rings off of the wrist seals inside of my dry gloves. They would be far too loose without dry gloves, but did also add a wrist warmer (fourth element, but a sock would do)
-Finding a set of dry gloves that are thick enough to not constrict blood flow with a liner
-Warm thermos and a massive fatty breakfast. Will Gadd has some old blog posts about this that I’d recommend digging around for.
Lastly, cold water immersion. Probably not worth it for most, but there’s a reason it’s mostly Finns and Norwegians doing the super nasty long cold stuff. Brown Adipose Tissue Development and Metabolism - PMC My understanding is 10-20min a day in 15°/60° water is no worse than extended periods in colder temperatures to generate a higher concentration of brown fat. An anecdote: While my training partner did put on 30lb during training for the channel and 20bridges swims, he credits most of his lack of cold (11hr in 15° water in a speedo) to frequent cold water baths.
For experimentation:
There’s the option to sew your own heated vest and panels if stock stuff isn’t cutting it. The Lola XXL has an extra heating element than the smaller sizes and gets you up to 80W of panels.
There’s also the ability to use a VBL or vapour barrier layer. I’m mixed, as it tends to make my feet slide relative to the sock. You can experiment with a thin sock, then a bread bag, then your normal layers. If you’re a heavy sweater, this may keep more of your insulation dry.
This all has gotten me up to 2.5hr in 1.5° water but with 2hr of it swimming. I do not thing I could safely do longer without a habitat and especially if scootering and then static deco the whole time.
