Kurt Jackson: The Lights Of West Cornwall, Messum's Cork Street, London

Kurt Jackson paints amiable enough, easy-on-the-eye seascapes and lighthouses in West Cornwall and the Isles of Scilly – or, to put it slightly differently, he is a recorder of that point where the land abuts the sea, and the eye stares out towards a fathomless nothingness, punctuated by rocky outcrops whose only sign of human habitation is the odd, lonely lighthouse.

Long shadows are flung across the sea. Fumy mists blow about. Birds perch on tiny outcrops. The manner of painting shifts from the wildly splashy to an almost combed meticulousness, and, where appropriate, Jackson adds bits and pieces of this and that to the surfaces – sand or netting, for example – in his pursuit of authenticity. He's after the tanginess of the place.

This huge show of 124 paintings is the culmination of a two-year project, and it represents a kind of diary or note-taking in pictorial form. We see that from the long, narrative titles, and from the way that they are often scribbled across the works themselves.

The vantage point is often high – Jackson has been hoisted up to snatch the view from some helipad – or low: a video shows him at work on a beach, painting and flecking and generally punishing a canvas as it lies flat on the sand. This plein-air painter works fast and furiously. It's a lonely vocation, but also one whose outcome has a ready appeal to the eye. Yet the sad truth is that, as paintings of coastal scenes, they are not, in fact, very good at all. They often seem forced and tonally inconsistent, or tonally crude. Colours, and the way they are juxtaposed, jar more than please.

Jackson often scratches into the surfaces of rocks to give them texture, but the scratches seem to hang there, unsatisfactory gestures towards a solution to a problem. Or the paint seems too thickly applied to no good end – look, for example, at Dawn, Porthtowan to Godrevy Lights. Does afternoon sunshine really stipple the sea molten? Do waves crash in bobbles? The effects, all too often, look neither consistent nor aesthetically right.

There is a great deal of strained painterly rhetoric here, but the paintings seldom hit home.