Howdy, Divenut2001. Yes, I am out here, although occasionally, such as the past three days (and tomorrow), I'm underwater.
As everyone has been saying, DIR is not about brand names. I would say the best recommendation is an undergarment that allows you the most freedom of movement with the least amount of fabric, and keeps you warm with a minimum amount of gas in the suit. With that said, I have 2 different undies that I use in Nor Cal.
Probably the undergarment most associated with DIR is the DUI 400g thinsulate, and I have to say that it's the warmest undie I have tried, even under a sqeeze and wet. The benefits are of thinsulate are pretty well-documented; maintains loft without needing a lot of gas, stays warm even when wet. The Thinsulate B used in this suit is even better, as it's made to work under compression. When I'm diving, I don't even feel the water temp; the negatives are that it's thick and may feel restrictive , especially if poorly fitted, and then packed into a poorly cut drysuit. DUI will custom cut this, but as with their suits, it's not a true custom. They start with a stock size and make adjustments to arms and legs. Mine was a stock Medium, which I had altered in Berkeley for $40, and it fits well. Something you may want to do is have the legs tapered as well, but other don't feel the need. DUI may do it for you, but you might have to threaten to go buy a different undie before they will.
Some divers on the West Coast have been using Diving Concepts Stretch Thinsulate undergarments. This undie feels like a true custom fit, and is slightly stretchy, as well as much more form fitting than the DUI. You may have an easier time reaching your valves, and kicking. However, it's not quite as warm, in my experience. It's lighter weight (the extreme, which is what you ought to buy for norcal) is only 200g, vs the 400g for the other. Also, the all stretch thinsulate isn't quite as warm as the stretch/non-stretch hybrid. But the benefit is that it's really easy to move around in, and doesn't have much slop at all to bunch up under a drysuit. I have a Stretch Thinsulate Extreme with a 200g vest, which you need for CA; without the vest, you may be chilly. And it's still not as warm as the 400g.
I said brand doesn't matter, but vague suggestions aren't very helpful. The Stretch DC has about 300 dives on it, and still works OK; the vest/undie combination makes it good for kicking dives in the 60-120 minute range. The DUI 400g is getting more use lately and has about 50 dives on it, and I am warm even after 120-150 minutes; then again, I don't get cold that easy. Of course this is all my personal experiences with my gear, and should not be taken as the end all/be all of DIR. This is all in Nor Cal diving, 45-55 degrees F, with singles, doubles,stages, scooters etc.
Let me know if you have any questions,
Joe Talavera
www.subtidal.net
