The sun-drying of octopus has been practiced –especially in Greece- for centuries as a means to tenderize the octopus before grilling. Fishermen probably hung them over the ships ropes to dry out.
The photo which was taken in Salala, Oman shows a simple and a smart method in which the drying of octopus is done in a kitchen container placed on a car hood taking the advantage of the relatively hot weather during that time. As expected, the period required for the drying would depend on the weather and the size of the octopus.