I have used both the flare 2009 98 and 106.
I have mostly been using the flare 98 because I feel that it fit my style and weight at best and I am about 74kg.
So my ideal size of Flare for you will be the Flare 106
. because you are 80 plus kg.
and since you are going to be using it in flat water and it will give you better balance and more enjoyable time on the water. fin size on this board can be 20cm for your weight.