This lightweight yet warm crewneck jumper is made from extra fine and thin Merino Wool yarn, righteously called Extrafine by its makers for its incredible water-repellent, elastic and crease-resistant qualities. A regular fit, this jumper features a simple crewneck in tension 14 yarn, is incredibly soft to the touch and extremely minimal in volume: in fact, the perfect layer to wear on crisp autumn days, under a jacket in colder months, or even on chilly summer nights. Personalised Sebago flag. In shipbuilding, the Keel is the backbone of a ship or boat and runs along the centre of the bottom hull from stem to stern.