There were always difficulties skiing on Windermere - for a start it doesn't slope down hill, so you need a speedboat to tow you.
Now that the limit is 10 knots, you have to have a bigger ski, and slalom behind the boat, so that your forward speed on the ski, is faster than the forward speed of the boat. (It's only POWERED boats which are limited - others can go as fast as they like!

)
Unfortunately that is not so safe, as the skier veers wildly from side to side, making passing more hazardous, and it uses more fuel (slightly).
The other main problem is that with less powered boats on the lake, the national Park have to provide more rescue cover, for yachtsmen and canoeists in difficulty, and are complaining about the cost!
SERVES THEM RIGHT!
In the meantime, the sport suffers!