layering wetsuits

Question
Hi Mike,

I have a 6.5mm wetsuit and dive in cold water. I'm not looking at dry-suits but I know several people who use a combination of a 3mm shorty wetsuit and a steamer. My question is: is it better to have the shorty underneath or on top of the steamer for warmth?
For maneuverability having the shorty on top seems to be the go but keeping your core warm by having it underneath seems to be logical.
Your thoughts please?

Answer
Hi Bruce,

I have to confess to not knowing what a "steamer" is.  I'm going to assume that it's a thinner, and possibly fleece lined, full wetsuit.  If that's the case then I'd definitely wear the shorty over the steamer.  

First, it will be much more comfortable that way.

Secondly, as you know, a wetsuit works by trapping a very thin layer of water between your skin and the wetsuit.  Once this water is warmed by your body, it's critical to keep it from moving around and possibly escaping...only to be replaced by cooler water from the surrounding sea.  Wearing the steamer under the shorty prevents water migration in two ways.  First, it provides a continuous layer of fabric right next to your skin and, while some of the fabric may be compressed somewhat by the shorty, it will still keep warmed water from migrating around.  Secondly, and in the same thought process, if you wore the shorty under the steamer then you've got a small gap where the steamer fabric rides over the shorty at the sleeve ends,cuffs and zipper.  These channels will allow water to move more easily and defeat the purpose of the wetsuit.

Bruce, I hope this provides the information you need to keep warm and make the best use of your exposure suits.  I apologize for not knowing just what a steamer is but I hope my guess was close enough to answer your question.

Thanks for writing and I wish you warm diving!!

Mike
mikescuba.com