Editing Longship (section)

===Sail and mast===
Even though no longship sail has been found, accounts and depictions verify that longships had square sails. Sails measured perhaps {{convert|35|to|40|ft|m|abbr=in|order=flip}} across, and were made of [[wadmal|rough wool cloth]]. Unlike in [[knarr]]s, a longship sail was not stitched.

The sail was held in place by the mast which was up to {{convert|16|m|abbr=in}} tall. Its base was about {{convert|250|x|180|mm|abbr=in|0}}. The mast was supported by a large wooden maststep called a ''kerling'' ("old woman" in Old Norse) that was semicircular in shape. (Trent) The kerling was made of oak, and about {{convert|700|mm|abbr=in}} wide and up to {{convert|6|m|abbr=in}} long in the larger ships. It usually heavily tapered into a joint with the internal [[keelson]], although keelsons were by no means universal. The kerling lay across two strong frames that ran width-wise above the keel in the centre of the boat. The kerling also had a companion: the "mast fish", a wooden timber above the kerling just below deck height that provided extra help in keeping the mast erect. It was a large wooden baulk of timber about {{convert|3|m|abbr=in|sigfig=1}} long with a {{convert|1.4|m|ft|adj=mid|long}} slot, facing aft to accommodate the mast as it was raised. This acted as a mechanism to catch and secure the mast before the stays were secured. It was an early form of mast partner but was aligned fore and aft. In later longships there is no mast fish—the mast partner is an athwartwise beam similar to more modern construction. Most masts were about half the length of the ship so that it did not project beyond the hull when unstepped. When lowered the mast foot was kept in the base of the mast step and the top of the mast secured in a natural wooden crook about {{convert|1.5|-|2.5|m|ft|abbr=in|sigfig=1}} high, on the port side, so that it did not interfere with steering on the starboard side.

There is a suggestion that the rig was sometimes used in a lateen style with the top cross spar dipped at an angle to aid sailing to windward i.e. the spar became the luff. There is little or no evidence to support this theory. No explanation is offered as to how this could be accomplished with a square sail as the lower reefed portion of the sail would be very bulky and would prevent even an approximation of the laminar flow necessary for windward sailing. There is no evidence of any triangular sails in use. Masts were held erect by side stays and possibly fore and aft stays. Each side stay was fitted at its lower end with a {{convert|150|mm|in|adj=mid|long|0}} toggle. There were no chain plates. The lower part of the side stay consisted of ropes looped under the end of a knee of upper futtock which had a hole underneath. The lower part of the stay was about {{convert|500|-|800|mm|ft|abbr=in}} long and attached to a combined flat wooden turnblock and multi V jamb cleat called an angel (maiden, virgin). About four turns of rope went between the angel and the toggle to give the mechanical advantage to tighten the side stays. At each turn the v-shape at the bottom of the angel's "wings" jambed the stay, preventing slippage and movement.