the whole length of a a window board - using a jigsaw (I've never used one before !) any advice ? - other than have 999 dialled ready on my mobile phone !
You've drawn a pencil line along it of course. How critical is it that the line of cut is exactly straight. Probably not I would guess. Anyway, try not to cut your leg off.
you'll find it quite difficult keeping a straight line with a jigsaw, even when you've got experience. Try and keep the baseplate down on the wood with a fair ammount of pressure. If poss arrange the cut edge to be the least noticed. Good luck
i take it , a window board is a sill board
put a pencil line on it where you want to cut-put it down on something where your weight on it will keep it steady(even the back door step)-cut about two foot or so at a time if it makes things easier-then slide the sill board each time to let you work in a comfy position