Thanks to Billy Arthur for sharing this picture and information about an old ‘luder’ horn which was used by the Shetland haaf fishing boats as a way of signalling between each other in foggy conditions.

Billy writes:

“This was an important instrument for da haaf fishermen. Another important skill for da haaf men wis da knowledge o da Moder-dy (mother wave) which always headed in the direction o land, and I imagine essential knowledge if you were at da ‘far haaf’, 40 miles oot, at the edge o da Continental shelf, ‘rowing Foula doon’ so to speak, and especially wi mist…

Some reckon da Moder-dy is an undercurrent, but I remember when I wis a boy, an old Whalsay fisherman telling me hit wis da seventh wave, which always headed towards land.”