Originally Posted by FuturaRider
Thanks so much for all these explanations, it all makes sense. My next sail down is an 8.0m2 and weigh 83kg. It's just that I found myself several times last summer 'near-planning' but not quite in 10-12 knot winds (Mediterranean) and have built up a fair amount of frustration. Given what you have just said, not sure I should even consider upgrading, an perhaps work more on technique.
If you were just off planning with the 8m, consider how the sail has been rigged (e.g. more shape with a slightly tighter leach is good for bottom end power) plus a bigger fin with greater lift is a must. Also a slightly higher boom helps with bottom end of the wind range. This maybe enough to get you on the plan.
All this with some technique adjustments and your planning before your mates.