Since we have this forum, I will include my initial response to Ed, along with a good friend's addendum.

If you do enough research, you find that dressing for the water temperature can be critical to survival. However, there are a number of ways you can manage your heat level above the water. 

• Many people do a little maneuver in which they grab the bow of a friend's boat, flip sideways to immerse themselves, and flip back up, using that bow they're holding for a great roll-up platform.
• Moulton has suggested saturating a cotton T-shirt on the OUTSIDE of your drysuit to enjoy the evaporative cooling effect.
• I often plunge my arms into the water and splash the water onto my shoulder and chest while wearing a wet or dry suit just to keep cool above water.
• You can wear a hat...dip it in the water occasionally and put it back on your head.
• You can do the same thing with a kerchief....wrapping it around your neck.

That's just a few suggestions. I'm sure that this great group has many that have yet to occur to me.

If you are wearing a Gore-tex dry suit, Once you get it wet on both sides with a dip, the fabric breathes and facilitates evaporation and thus cooling. Fabric has to be wetted thoroughly via a good dip with a buddies bow.

A member,  Azure has asked these questions:

I am a new OOOPS member and I have some questions about cold water gear. 

When you say 'minimum immersion equipment: drysuit,' is a two piece drysuit okay?

With a drysuit does the drysuit need to have built in socks? If not, then what is okay for foot coverage?

Thanks much,

Hi Ed,

I think OOPS guidelines on drysuit use are a great place to start for most paddlers & trips.  I also like the "120 rule". If the water temps and air temps add up to less than 120, dress for the water. For me I do similar to what Tim Mattson posted on the OOPS list-serve.  That said, I know Tim's skills.  I also know mine and know that I would wear a drysuit in conditions that he wouldn't because I haven't been paddling enough lately and I know my skills aren't as sharp as they were a couple years ago.

 For me, a drysuit was a great investment and actually helped me improve my skills much more rapidly than would have happened had I continued to use a wet suit and various iterations of dry tops, smash tops, etc. I found that when I wasn't as concerned about getting in the water I'd practice rescues, rolling, etc more often. I wasn't scared to try new strokes in dynamic water because I simply wasn't concerned about getting wet or cold. 

In regards to the question someone posed regarding a two piece drysuit, it all comes down to whether it's actually dry.  If you're curious, try it out in conditions where you have a safety net. I have bibs and a couple different tops. Even if I'm really careful rolling them together, I still get a bit of water entering the suit, though I don't think it's enough to be more than an annoyance unless it was a really long swim, and odds are, if I were in conditions where a really long swim was a possibility, I'd probably be in my full drysuit.  My own opinion is that used correctly, a two piece drysuit should suffice on an OOPS trip as the odds of a really long swim aren't that great.

My thoughts regarding drysuits:

1) My bottom line is they're a great investment and can make you comfortable in a much wider range of air and water temperatures than any other configuration

2) If you swamp out the inside of your drysuit with sweat, you significantly decrease its ability to protect from hypothermia because you lose heat rapidly via conductive transfer once you're swimming. It's important to stay cool enough that the insulating layers between your skin and drysuit can do their job.

3) Especially with a PDF and spray skirt tunnel, it's difficult to get much cooling benefit from evaporation. If you've been maintaining the DWR on your drysuit, the water just beads off anyway.

Better to just flip the boat and hang out upside down for about 10 seconds. Conductive transfer (i.e. that same effect that gives you hypothermia) will cool you off much faster. If coming back up is a concern, just dip yourself while hanging onto the bow of another group member.

4) It is possible to dry out once you've sweated inside a drysuit. Gore-Tex works because of vapor pressure. This means if your body is hot and you're effectively in a Gore-Tex glove fully immersed in cold water, vapor pressure will help push the moisture through the suit into the surrounding water. 

5) It takes just a little accident to rip your drysuit and fill it with water so be equipped for repairs. Gorilla tape can help you limp in. Also, test your drysuit before every paddle -- I like to go for a short swim. This gets the air out and verifies beyond a shadow of a doubt that you have no significant leaks and didn't accidentally leave a zipper open.  You do not want to discover during an unplanned swim far from any takeout area that you accidentally left a zipper partially or fully open.