Ive just obtained a wooden planked IOM The hull is in need of a re varnish . I would like to keep the natural look so looking to re varnish. Obviously a good sanding to remove the old stuff. Is yacht varnish the stuff to use or is there some thing better. Does the raw hull need any sort of sealer before varnishing etc Or does a sealer go on top of the varnish I believe the hull is Mahogny