Central mainsheet jammers are an important bit of kit. They don't feature on all types of boats, but when they are used it's because they play a vital role in helping the helm or crew. Be it with manoeuvres or freeing up a hand to pull something else. Those that have sailed a single-handed trapeze boat, will know especially well how important they are.
 

However, most people who have sailed a dinghy or keelboat with a centre-mounted mainsheet jammer will have come across the issue of the jammer not rotating to the correct orientation after a tack or gybe and causing the mainsheet to get wrapped or twisted. It's extremely annoying, and in a worst-case scenario can lead to a capsize or broach.
 

We wanted to solve this issue, so we did!