I'm with Carl. Until I can afford the RIGHT drysuit (not the cheapest), I've managed to get by with a 2-piece spray suit and fleece underneath. It worked in 40 degree (F) weather and 30 kt breeze, but not as warm as a drysuit.

Fleece seems to help retain heat even when it is wet, which is good. It's soft and flexible, and lighter than wool.

With my spray suit (bib and top) and the harness on, it was strange that water only goes up to my mid-thigh if I take a swim for a minute or two (because of the harness straps). The top portion stays dry for up to about 10 minutes. But because of the fleece, it stays a bit warmer even so.

Of course, when you're wet, it's a bit harder to haul your butt on the boat...