Today's research snippet - shiver me timbers!

Today's research snippet: 
Today it's back to Alexander Nequam, milk brother of Richard the Lionheart, and his descriptions of daily life in the 12th Century: Here he talks about aspects of a ship:
If anyone wishes to fit out a ship let him have an asbestos stone, in order that the benefit of fire may not be lacking. If such hearthstone is once lit it is unquenchable. He should have a needle placed on a pivot; the needle will rotate and revolve until the point looks toward the east, and thus sailors understand where they should steer when the Little Bear constellation is hidden in the storm, although this constellation never sets because of the brevity of its circle.
it is necessary also to be supplied with grain and wine, also with arms and with an axe by which the mast can be cut down when a storm comes up, which is the greatest of evils, and so that the traps of pirates can be avoided.
Side planking should be fastened with cords and nails, and, when fitted together, let them be daubed with pitch mixed with wax on the inside, or with paint and let them be smoothed on the outside, sparing the use of too much paint. Cross weaving and wattling are required, in order that the swift and frequent jarring is may not and fasten or loosen the joints. It is needful to join the boards proportionally, with the fore castle and after castle separated.
Let the mast be raised in a socket on the flooring, then let the sail be fastened to the mast, and have the cordage extend from side to side; the lowest part of the sail is fastened to a spar carried cross-wise. The swelling of the sail is its belly. Yard braces are needed; May these be placed almost before the water of which the upper ends are called horns. The sail yard is at the peak of the mast and in French is called a cochet.
Let there also be openings through which oars can run, if rowing is required when a wind is lacking. Let stays be extended,
Let the skipper have a transverse seat or thwart. Near this let there be a windlass that the lines may be bound more firmly and that the sail may be raised according to the shift of wind. An anchor is needed. Have a mallet by which the sailor gives signals to his comrades.

Today's research photo: These are ship's timbers from the mid 13th century.  They ended their life as a lining for a fish tank on the south bank of the Thames. The upper plank has holes for oars to pass through.