.......Minnewaska could consider a spline repair if the crack is long and kind of straight. That would involve setting up a jig so that you could use a router to cut a fresh clean square channel where the crack is, then make a spline out of a bit of teak to fit into the channel. Once the channel is solvent cleaned, West System is your best pal in the adhesive department. Glue in the spline, sand it flush, finish with varnish.
This probably is the right thing to do, but a bit challenging.
To describe the crack a bit better, the piece is close to a 1" x 2" strip that is approx 3 feet long. It lies on its flat 2" wide side to made a piece of trim on the cabin top. It serves no purpose other than decorative. The crack is along the lengthwise grain in the wood. It extend approx 2/3rds the length of the piece, out the end grain at one end, but not entirely to the other end. Therefore, the piece would not come in two, if removed. It is screwed down with the holes plugged with teak dowel.
I could drill the dowels out and remove it easily enough. However, there is some structural integrity to the piece that would be destroyed, if I completed the break. I suspect that just separating it enough to get some epoxy inside could break it anyway.
I don't currently intend to varnish it, as I've adopted the grey look on all teak outside of the cockpit. Although, unless it is fully sealed, no varnish product would ever stay adhered to it.