Staying both warm and dry makes any kayaking adventure that much more pleasant. I’ve been kayaking for over 25 years now and am amazed how much the kit has moved on during that time. Way back then getting soaked to the bone was pretty much a standard feature of paddling even if you didn’t swim. Even though staying dry is much easier and therefore makes keeping warm itself so much easier it’s important to get your insulation layers right.
I tend not to feel the cold as most folk but I still pick my insulation layers really carefully to make sure that I not only stay nice and warm but that I do not over heat. I personally find overheating way worse than being too cold.
As in any outdoor sport layering is the key. A few thin layers will always be better than one big thick layer. For most normal conditions in the UK I wear a thin merino thermal top, long or short depending on the dry top/suit I am wearing and will often supplement this with another merino thermal. As yet I have not found the need to add another or thicker top to this setup.
On my legs I’ll wear a pair of merino longjohns and a pair of Ronhill tracksters. If you were into climbing in the late eighties through to the mid nineties you will probably have owned a pair of tracksters at some point. I find that wearing two layers under my dry suit/pants helps keep the chill of my backside when I am sitting in the boat.
Many paddlers like to wear a one piece suit (onesie) under their drysuits. I can see the logic but I much prefer the ability to mix and match my layers to get the right level of insulation for the given conditions.