my ski partner has a portable course that we leave in. Once it get a cross breeze it's always a banana. Like Ed said, a bucket of concrete just doesn't work as an anchor, horrible shape and it rolls. My concern with a portable course is and maybe @Ed_Obermeier can shed light here is: typically a portBle course is dropped in calm water, skied, pulled up, done. If you leave it in and put serious anchors to keep it tight, when it gets a 15 mph cross breeze now instead of bowing and the anchors dragging you are adding a lot of strain on the course that it's not designed for being 800+ feet long with flopping PVC arms 41' long, it's like a sail catching a lot of energy, how well will hold up like that?
I might have put a permanent course in two weeks ago. It's a homemade hybrid style course. After watching our issues with the portable course I decided what I wanted done differently. I essentially copied a portable main line minus the PVC turn buoys and arms. Screwed two mobile home anchors in lake bed, 4 (112lbs total) blocks on opposite end and used a harbor freight cum a long to keep tension on line. Then I took an old garbage can, cut it 8"x30" disc shaped sections for a concrete mold and filled with 80lbs concrete and attached a sub buoy for the turn buoys. FYI proto type was 55 lbs and didn't seem like enough once I sunk it.