I had our canvas guy add snaps when we did ours. You can see them on the front of the cockpit cushions and they wrap underneath on the stern perch seats.
So far they've held on through some pretty good storms.
The other simple change that made a big difference was breaking the port cushion in two so you can open the locker without flipping the whole cushion up; makes it a lot easier getting in and out of that locker.
It's the little things that make a big difference sometimes.
Those are really nice and I like the snap idea. We might think about that with the new ones. We also spit our bottom cushions and back cushions into 2. The use of them is more versatile for us. Ruth and I will at times be sitting on the same side and I like the back cushion and she doesn't.
Thanks for showing that,