I'd like to paddleboard a bit during the winter. Living in Vancouver, BC, our seawater temperature goes down to about 7C (45F) in January. It's at 12C (60F) right now.
What I am concerned with are the best arrangements of clothing to paddleboard. This is a similar question to people asking the how to plan for winter hiking. In that case, the general recommendation, which I have followed in the past, is to dress in layers and avoid sweating which would sap heat as soon as you stop.
On a paddleboard things will be a little different:
I am going out for 60-90 minutes and will be going at a fairly brisk pace during that time.
I won't go out when it rains. Probably only when sunny and > 5-10 C. (40-50F)
I can't really take clothes on and off and put them somewhere.
One goal is to avoid hypothermia if I fall in (I rarely do, but it can happen). If so, I accept I'll just be miserable on the way back to my starting point.
Rather not expose goretex to salt water.
Currently I have a Farmer John (link isn't my specific model, just illustrative), which is good for in case I fall in as it will protect my core from heat loss. I wear it with the top down, so it really only comes up to my waist and have a belt CO2 expandable floatation device.
This question is mostly about my upper body. I suspect I can wear a jacket and then open it up as needed.
Edit: I am mostly concerned with managing heat buildup the 95% of the time I don't fall in at all, while wearing clothes to protect from hypothermia if I do fall in. I have experience with cold water, having gone swimming in mountain lakes and 2-3 Polar Bear swims as well and I will never be more than 200-300m from shore, in a harbor area.
Edit 2: As I am going at a brisk speed (5-5.5 km/h) close to shore, my main concern here is to keep from overheating, just as you would if you were slow-jogging in sub-zero weather. The advice there is - start out a chilly level, because heat build up will result in sweating through your clothing, which is neither comfortable nor safe. High speed paddleboarding requires a fair amount of up-down motion from your trunk above your hips, way more upper body movement than most casual kayakers. Your legs are mostly immobile and exposed to the elements however. I'm close to shore, good weather, leashed to the board which I can easily climb back on. The water temp is not something I'm very worried about for short immersions. The particular risk-comfort tradeoffs I am making are my own and may not apply to you, but I am not asking for kayaking gear recommendations here.
Anyone gone through this and have some advice?