Well I'm no expert, but as a rule its two fastenings per plank, certainly for a folkboat where I suppose the planks are 2.5 or 3" at their widest.

I always find making a template from scrap cardboard (keep those flatpack furniture boxes somewhere dry) are excellent for this. cutting blocks to fit the stepping of the inside of the hull before adding the laminate strips is a good idea. And you'll need quite a few G clamps.