Two words Ocean paddling One more Clapotis
One word about those conditions: kayak.
To paddle in rough open ocean or clapotis the important thing is to have the right hull. The right hull is one designed to sit on or near the bottom--a decked kayak or undecked kayak such as a surf ski. These sit-on-or-near-the-bottom hulls are appropriately paddled with double blades. One can paddle a SOB hull with a single blade but, to me, it's mechanically awkward and unappealing.
Pack canoes are not designed for open ocean, but as sit-on-or-near-the-bottom hulls, they too are best paddled with double paddles.
There are hulls designed for single blades that can handle rough ocean: sit-near-the-bottom decked canoes with rudders, and outrigger canoes. If one is going to paddle in rough ocean or ocean-like conditions, the best thing to do, in my opinion, is to choose an appropriate hull, not to rely on a double paddle in an inappropriate hull.
I thought the topic was day paddling or tripping in a traditional CanAm open canoe hull with a double blade. It makes no sense to me to day paddle a traditional canoe with a double blade. If that's how one wants to paddle for fun or exercise, I suggest getting a better hull for that technique--namely, a fast and sporty decked or undecked kayak. If one needs the space of a CanAm open canoe for tripping loads, I can understand using double blades if one does not confidently have "reasonable single blade wind and wave skills", which was my stated premise.
The main reason I did not have solo confidence in flat water wind and waves 30 years ago--even though I was a solid class 3 whitewater paddler--was that I was paddling the wrong hull with the wrong flatwater correction technique. I was trying to horse a heavy tandem canoe with a novice (and evil) J stroke. That was tiring, stressful on the wrists, forearms and shoulder, and flat-out unpleasant after a few miles.
Once I got into a light and fast solo canoe and learned the traveling C stroke, the pitch stroke and the Canadian stroke, all the stress and unpleasantness transformed magically into proprioceptive and aesthetic bliss. I was then able to combine my whitewater wave and J lean lower body skills to confidently attack flatwater waves and wind with a single blade. To finish of the skill package, I had to learn reasonable Minnesota switch technique and become reasonably ambidextrous with the single blade on both sides of the canoe.
You
have to become competent, comfortable and confident on your off-side in wind and waves. That takes practice--preferably when you are young. That's why I advise all beginning open canoeists--those who really want to learn the rapidly dying art of the single blade--never to touch a double blade. It's like crack cocaine.
First: Learn how to completely control an open canoe with a single blade in all water and wind conditions, using all available single blade techniques. That will take a few years of practice, but the rewards are rich.
Then: You can play with a double blade if you like, without feeling that you have to.
To those who are experienced or whose paddling habits are fixed, I'm not addressing you.