I wish I had gotten into making canvas covers back in Dago, I knew a guy there that made pretty good money doing it, and there were always folks who needed covers due to the number of boaters out there...
Only cover I ever had made was for the padded hiking strap aboard my Laser... I had part of a pool noodle for padding over the webbing, then this rectangular cover with Velcro stitched lengthwise along the edges.
It worked great, and I could easily remove it to rinse salt water from the canvas... best of all, a friend made it for me out of a scrap of blue canvas and some Velcro he had in his garage, so it didn't cost me a dime, LOL.
My friend was a strack ex-Army paratrooper, and somewhere along the line he learned to operate industrial sewing machines (to repair chutes & harnesses). Kinda weird, seeing this burly combat killer sewing up my hiking strap cover, but he did a good job, the thing lasted for years & years.
For a full-sized cover as shown in the video, I'd probably just buy one, since I have zero experience with sewing machines... me beloved & dear departed mum was a pretty good seamstress, had her own Pfaff machine and everything, but I never developed the knack.
