I used to catapult when getting my back foot in the footstrap. I used to get in harness lines, then starting planning and get the front foot in the straps and then move back and get the back foot straps, but a lot of times with the gust or chop water i would miss the back strap and then catapult.
I solved this problem by doing the following:
1 - Get in Harness line
2 - Getting planing
3 - Get in front foot strap
4 - Out of harness line
5 - Get in back footstrap
6 - Get in harness line again
This avoids me a lot of catapults now.....thank God....