Philip Marsden’s new book is subtitled ‘A Voyage of the Imagination’. During the course of his voyage, he incorporates some intriguing thoughts about Celtic mythology and the splits it reveals in the ‘fabric of the world’. But this is really just literary window-dressing. At heart, this is a tale of good old-fashioned adventure, and all the better for it.

Marsden decides to take a 31-foot sloop from Cornwall to the Summer Isles, off northwest Scotland, and to do it the hard way – not up the sheltered Irish Sea (‘for pussies’, an old sea dog tells him), but along the Atlantic coast of Ireland, with its treacherous islands and rocks.

While a competent sailor, he is not an experienced one, so the reader will share the state of continual mild anxiety he describes as he makes his way north single-handedly in a relatively small boat. Halyards jam,