HUNT'S THE ordinary method of constructing jibs is to have the cloths run- In describing his method Mr. Orr observes, " Its advantages are, to produce a more favorable effect of the power acting upon the sail, than what is produced by the old established method of construction, and consequently imparting a more advantageous impulse to the Orr's jib is a very strong and flat standing sail, when properly NO. 1-VOL X. B constructed, it is also known amongst yachtsmen under the name of the "Scotch cut jib," probably from the fact of its being principally used by Scottish yachts. For the method of construction, see plate 44:-With the lengths of the three sides of the proposed jib, construct a triangle ZYX, then make an allowance for the proper roach, or arc on the luff of the sail; this is done by setting off from 2 to 3 inches for every cloth in the sail, at right angles to the straight line zy and opposite to the clew, and then describing the roach or arc through its extremity; then taking x as a centre describe the arc a b, and with a and b as centres describe arcs cutting each other in m; draw the line x m w, which will bisect the angle X. From w let fall the perpendiculars w e, on z X and Y x; xe equals the amount of the seam gores. Divide we into as many equal parts as there are cloths required to fill up that space, and through the points of division draw lines parallel to z x and y x respectively, and meeting in the line w X, from which the length of every gore to the scale of dimensions may be accurately found, as the perpendiculars zc of the small right angled triangles shown z c d at the head of the jib in the plate. Next comes Mr. Andrew Taylor's plan for constructing a jib, in which he gores the after-leech as well as the luff and foot, gets the foot gores more approximating to a thread of the canvas, thereby obviating so much stretching, and reducing the roach on the luff: for it is to be observed that the roach comes in as well to assist the stretching of the sail at foot as to meet the strain from the clew. This jib stands very flat, and forms a powerful and effective sail; to make a draught of this sail, see plate 45. Take the lengths of the three sides from a scale of equal parts, and describe the triangle z Y X, give the proper roach or arc to the luff z Y, and the foot YX; then take a square a X b, and place the right angle on x at the clew of the sail; with a pair of dividers take the widths of the cloths that are gored in the after-leech from the same scale of equal parts; put one point of the dividers on z, move the top of the square until the side a x touches the other point at right angles to it, and mark the point a; then draw lines to the sides of the square as seen in the plate, and the line y b drawn from Y at right angles to the side of ths square x b, will give the requisite foot gore. Divide z a and xb (whcih are equal to the widths of the cloths in the leech and foot) into as many equal parts as there are cloths, and through the points of division draw lines parallel to x a, from which the depth of each gore can be accurately found. Mr. R. Kipping's plan for an improved, or modified Angulated Jib, is a combination of the principles of Orr's and Taylor's methods. It differs from Orr's in having the joining seam in the body of the sail, lower down on the luff rope, and more in the direction of the direct strain of the jib; and from Taylor's in having the upper cloths more oblique to the leech, and having much less gore on the Corres Depth ponding on the Length Selvage. of TABLE L-FOR EIGHTEEN INCH WIDE CANVAS. Length of the eating in seaming to be allowed on the selvage according to the width of seam. Gore. ~400 222222∞∞∞∞ 1222 22 2 2 2 ∞∞∞∞334 222222222∞∞∞∞ luff, approximating more to a thread of the cloth. It is calculated to make an exceedingly strong, flat standing, and most effective sail, combining the best properties of the other two, with a better distribution of the canvas whereby to ensure equality of stretching all over the sail. For the mode of constructing this jib see plate 46: with the length of the three sides, taken from any convenient scale of equal parts, construct the triangle z Y X, describe the proper roach or curve TABLE I.-(Continued.)-FOR EIGHTEEN INCH WIDE CANVAS. 6666aaaaa666 9 9 9 7 9 81 8 9 9 9 9 10 9 10 9 111 01 10 11 10 110 21 10 210 3 10 310 4 10 410 5 10 10 510 64 610 7 10 18443830 788∞ ∞ ∞ ∞ ∞ ∞ σ aaaaaaaaaaa966 1400-400-400 8 10 113 12 12 12 12 2 122 123 41 124 5 12 64 811 11 on the foot Yx and luff z Y; draw the line x w from the clew to the luff in the direction of the strain of the jib sheets; then with any radius xa, describe an arc a b, intersecting x w in m; make, mb equal to m a, join x b and produce it to T, and the angle mxb will be equal to the angle mx a, and therefore x w bisects, or equally divides the angle Y X T. From w let fall the perpendiculars We on XT and X Y respectively: produce we to any indefinite length, and from z let fall the perpendicular z d upon it. Divide TABLE IL-FOR TWENTY-FOUR INCH WIDE CANVAS. |