I made a similar comment in another post today so, I decided to address this directly for those who’ve never used a wetsuit. Wetsuits are intended to be used in water. Underwater, there is no evaporative cooling so you stay warm (assuming proper fit, thickness and time in water). In air, a wet wetsuit constantly cools you (assuming an open cell neoprene that absorbs water). A wetsuit is actually a better choice for a hot day than a cool one. Spend a day on the water in a wet wetsuit and you will probably go hypothermic.
You make a good point about wet suits, but your alternative suggestion in the other thread (a windbreaker) was about the worst possible option available. If the problem is evaporative cooling, which it mostly is in air, then in cold conditions you are still likely to be warmer in a wet wetsuit than with a wet windbreaker on. A wet wetsuit still has insulating properties, though not as good as dry lofted insulation under a dry suit. A fleece pullover on top of a damp wet suit is quite warm indeed and you still have some thermal protection for unintended swims. When kayaking you need to consider both the air and water. The water is usually the more important factor because of how quickly and effectively heat is removed by conduction.
Wet suits were never designed to be the best choice for kayaking, despite many people taking this cheaper option early on. For the average kayaker they are better than no immersion protection but not as good as a dry suit.
Some good reading for the OP:
I’ve spent many days on the water in a wet wetsuit. In a sea kayak, with a skirt and lifejacket, there’s really not much exposure of the wetsuit to the air. The reassuring thing about a wetsuit is that it can sustain damage and remain effective. A drysuit is kind of like a car tire. So I’ve never been too down on wetsuits, even though I also have a drysuit. Spending time out of your boat on shore, while a worthwhile part of many adventures, is usually not the critical life and death moment. A properly fitted (and properly fitted is the part that seems a majority of kayakers wearing wetsuits get completely wrong - it needs to be skin tight, and it will feel at least somewhat restrictive) wetsuit can add a huge degree of survival time. A wetsuit provides a lot of insulation even if you stay dry all day. The more active your endeavor, the more you’ll feel it. I see a value in the post with regard to considering what your paddling day looks like…figuring how much time I will be po-dunkin around on shore, and then preparing accordingly. If you’re in a wet wetsuit, then it’s likely quite good that you have one on. Just control the exposure to evaporative cooling if you start to feel cool on shore.
For the past several years most decent quality full wetsuits have front panels coated with a material that sheds surface water and blocks wind, so your core is not really experiencing any more “evaporative cooling” than you would experience in a dry suit. My last suit like this cost $120 on spring clearance. You can spend a lot more on a crappy drysuit and not be safe in rough water conditions.
Evaporative cooling? Yes quite a bit. But pfd, skirt and gloves I often get sleeves wet for cooling.
On those out of the boat I use a spray jacket or a cag. I recently paddled ona chilly day in Alabama with the cag. on.
Spend a day on the water in a wet wetsuit and you will probably go hypothermic.
Spent many days on the water in a wetsuit, and never got hypothermic.
These debates about wetsuits often are about the old farmer Jane or John rather than a lot of what is actually out there in fancier wet suits.
These details matter. While they don’t work well for me compared to dry wear, as seadart says above, there are fancier ones that have wind blocking and thermal layers. Whether these would work for paddling as well as boarding is a matter of individual preference, but credit needs to be given where it is due.
The other thing is having a good windblocking top rather than a cheapo shell. As the temps drop this matters more.
I don’t bother with wetsuits anymore. I go from nothing to a progressively layered drysuit. Since a drysuit on it’s own offers zero thermal insulation you can layer up in small steps that would suit the conditions. A lightly layered drysuit can easily less warm than a modest 3 mm wetsuit.
My main reason for abandoning wetsuits is how disruptive it is for my posture in a surfski. But I quickly realized that there is basically no need for a wetsuit at all.
OP brings up a valid point. But evap cooling of a wetsuit can be addressed by wearing a wind protection layer over it. I used to always carry a windbreaker and a pair of splash pants when I was in a wetsuit which worked ok. I often carry a windbreaker during the “nothing” season. In summer a wet synthetic shirt can evap cool you successfully.