Small Boat underdeck furling units are ideal for sportboats and daysailers from 4.8 m to 9 m (16 to 30 ft). The drum is located beneath the deck, lowering the tack height for maximized sail area. An optional hoistable ball bearing halyard swivel can be installed on your headstay so you can raise or lower the sail without removing the headstay. Swivels are independent of the headstay, allowing you to tension the luff separately from the mast rake.