Starboard start style deck padding. I can get my hands on an old free formula board (sorry dip916, not yours). I want to convert it into a kids learner board. literally just to float around on non planning, so I am thinking the width of the free formula will be good. They won't be in the straps or turning so I not worried about the sharp rails. What I would like to do is cover the board with the type of grip that comes on a starboard start. Any ideas where I can get some really cheap stuff.

You want EVA foam. Try Clark Rubber.

cheap yoga mat?

Forget Clark rubber they sting u BAD
Look for anywhere that sells closed cell EVA foam that is not Clark rubber lol

For watersports (with some grip cut into it)
pjbowers.com.au for very think boat deck stuff - umm 'Deck Tread' I think
australian jetski parts (on the seadoo website) for 'Hydroturf'
They are both about $80 for a square meter


Or pjbowers also sell standard EVA 10mm sheet for 2m x 1m is about $60.