I had to make a better skeg with pivot bosses as I found Sand did jam it up

The easiest system I have found for preventing sand from jamming the skeg is to located it an inch off to one side of the keel.

By placing the skeg away from where it is most likely to hit the sand, you make it much less likely to get sand in it and thus less likely to jam.

The skeg in install on my Petrel uses a well supported cable that positively pushes and pulls the skeg out and in with good leverage, so if sand does get in, I can usually force the skeg to work without much effort. I also made the skeg box fairly wide with a small spacer to keep the skeg centered. The small contact area of the spacer reduces the chances of sand getting just to that spot, plus the spacer is located high in the box when retracted so any sand would have to be pushed way up to cause a problem.

There is probably enough info in the drawing below to reproduce the skeg, or you can get my plans http://www.guillemot-kayaks.com/guillemot/catalog/accessory_plans/sea_kayak_retractable_skeg_plans