if your board is made from epoxy dont use flowcoat. flowcoat is polyester resin with heaps of pigment added so its incompatable.
you can put epoxy on polyester flowcoat but not the other way around....
just chamfer the crack back with grinder through the damaged area out 50mm on either side. then fill any deep gouges with qcell/microfibre/microballons/talc (depending on cost and if you give a **** about weight)
so now you have a area which should glass that is like this shape but blunter angles. (the filler is just filling any voids that wouldnt glass
/
\_________/
(not as deep.)
then just laminate with epoxy some rectangles of glass like 2 six ounces (cloth weight) or so
after grind back flat
fill weave of glass with filler
fair
mask rectangle wider than all sanding scratches
sand shine off up to tape (so paint will stick)
undercoat
sand undercoat flat (ie get rid of brush strokes)
mask new rectangle slightly wider than undercoat and again sand off shine
sprey 2 pack with touch up gun 2-3 coats

or just stop after glassing but sand off jagged edges first....
sorry for ridiculusly in depth reply been at work all day