Presuming that a canvas sail is to be turned into a boat cover, a wooden ridge should be fttted to support the cover, fore and aft resting on the breast hook forward, and the stern aft. The cover must then be made, if possible, in such a way that the seams will be athwart-ships, i.e. at right angles with the ridge over which it will be stretched, and secured by lacing through eyelet boles worked (or clinched,if metal) in every seam through the double part. For waterproofing use ordinary paint containing ochre, or one of the earth pigments in preference. Lampblack is also good, but does not reflect the sun's rays as do Lighter colours. For the first coat use equal parts of boiled and raw oil and a little turps, and allow plenty of time to dry; omit raw oil in the last coat, and omit the pigment in the first. If it is not possible to make the cover with seams athwart, let them be fore and aft (not diagonally), and work a tabling for the eyelet holes.