The varnish I've used starts out milky but sets clear... I hope. The tide mark is now delineated by a line of sea weed. Not sure it completely works but I'll let it all dry out and see what it looks like then. The weed is some feathers soaked in paint and PVA.
I've also started working out what the scenery will be on this board; I was tempted to start gluing things down but I will discipline myself and make sure the track is down and wired first; at least on this bit of layout.
On the right hand bank the country side will rise up so that the line is in a cutting as it leaves the board, this will blend it into the next section. I'm also planning to have a wonky wooden footbridge right against the backscene which will hide the join and allow the fisherman to get from his cottage to his boat.