What characteristic of the Otterhound's coat provided superior waterproofing and insulation against the cold?

Answer

Dense, oily double coat

The breed possesses a dense, oily double coat which was essential for insulation and providing superior waterproofing necessary for working in fast-moving, icy water.

What characteristic of the Otterhound's coat provided superior waterproofing and insulation against the cold?
animalconservationstatusDogOtterhound