: My mother in law just bought a cape Ann expedition from a fellow in
: town, ( she couldn't not have a wooden kayak after seeing mine
: last year). Anyway it could use a freshening up as it is four
: years old and has some good scratches in it. Question is how
: much material to re varnish this kayak? I don't know the amount

I would suggest a quart of good marine varnish, some mineral spirits to thin and a handful of disposable foam brushes. Plus 320 grit wet sand paper for between coats. Give it 4 or 5 coats and she will have a new boat!
Of course one or two may do it but once started you may as well go ahead and work on that shine