PLANKING 72. The planking of a boat is quite an art. A house carpenter can measure the length and width of a roof and tell just how many boards of a certain size it will take to cover it, but a man cannot tell, by measuring a boat, how much lumber it will take unless he has learned by experience how much waste there will be. Every change in a boat's shape makes more or less waste in getting out the planking; while this waste also depends on the character of the lumber at hand with which to do the planking. Some boats require crooked plank to cut to advantage, while others require straight ones. 73. Woods for Planking.-The size of the boat determines in a measure the kind of wood that shall be used for planking. On most small boats, from 30 to 40 feet long, white cedar is generally used. As cedar runs in market lengths of 12, 14, 16, 18, 24, and sometimes up to 32 feet, it would make too many butts to use this wood for the planking of larger boats. Yellow pine of the long-leaf variety is more suitable for boats over 35 and 40 feet, because it may be procured in very long lengths and is not so expensive as cedar, while being a tougher and stronger wood. Oak is the best wood for the plank next to the keel, known as the garboard, followed by a couple of yellow-pine strakes as each line of plank is called. The first plank next to the garboard on either side is known as the first broad strake, the second the second broad strake. The top plank of the hull proper, not the raised-deck part, but the strake that comes flush on top with the main deck beams, is called the sheer strake, as it is the plank whose edge outlines the sheer of the boat. 74. When planking a boat, the work is started alternately from the deck down and from the keel up. The last plank to go on, the one that closes in the hull, is called the shutter. The various planks referred to are shown in Fig. 65. Sometimes a boat is so big around the middle and so small at the ends that to use the same number of planks from end to end would make them come too narrow at the ends. A plank or two are then worked in that do not go all the way to the ends, but merge the two into one; such planks are called stealers. 75. Butts.-A boat of any size with her planking in one piece from end to end. is a rarity. Owing to the crooked shapes the planks have to be made it is difficult to get lumber from which they can be so cut. A butt, or the joint where the two ends of a plank meet, if made properly is stronger than the board itself, as it is backed inside between the two frames by an oak block called a butt block that is about one and one-fourth to one and one-half times as thick as the plank, and is wide enough for its edges to lap over the planks above and below it, as shown in Fig. 66 (a) and (b). This gives additional strength to the butt. Only an inexperienced builder would try to nail both ends of the planks forming a butt on to one frame, as in (c), as such a construction is not only faulty but dangerous. In some very lightly constructed boats, the planks are halved together and the joint glued and riveted. The lap on the outside is never allowed to come to a sharp edge, or as boat builders call it a shim point, as it will curl and split with the Outside Inside FIG. 67 heat of the sun. It is always cut so that it is at least inch thick. The inside, however, may be a shim edge, as shown in Fig. 67. 76. Carvel Plank.-There are number of ways in which the planking of a boat are joined at their edges so as to make the seams water-tight. The general method in use all over the United States is what is known as the smooth, or carvel plank, where the edges lie square one against the other. The inner edges should fit closer it is called when the seam has a wider opening on the inside than on the outside, the pressure forces the caulking through the seam and causes it to leak. The right and the wrong ways of caulking seams are shown in Fig. 68. 77. (c) (b) FIG. 69 (d) Lap-strake, or clincher built, boats have the planks overlapping each other and the lap riveted together as shown in Fig. 69 (a). Such seams do not have to be caulked. Hollow and round planking, shown in (d), is an attempt to make a seam tight without the use of caulking. By forcing the round edge tightly into the hollow of the next plank a water-tight wood-to-wood contact is obtained. This is not a good system to follow, as unless the seams are absolutely perfect and watertight it is impossible to make them so. Strip-built boats, shown in (b), are boats whose planking is a series of parallel strips nailed edgewise together as well as to the frames. Bevel-lapped seams, shown in (c), are used in light construction, the edges being beveled off acutely and then laid together in glue and varnished. Halved lap seams, Fig. 70 (a), are a modification of the bevel-lap seams and are riveted together in the same Halved Lap Seams. (a) Ribbands. (b) Double Planking. (c) FIG. 70 79. Double-planked boats have two thicknesses of very thin planking, sometimes with only paint between and sometimes with painted or varnished canvas. This method is illustrated in Fig. 70 (c). Diagonal-planked boats are almost the same as the doubleplanked, but the inner thickness is laid across diagonally. Sometimes a second diagonal thickness at right angles to the first is laid over the frames and then the third and final thickness of plank is laid fore-and-aft over all. This crossing of the grain makes a very strong sort of veneer construction. Mahogany is generally used for the outside planking of boats built in this way as it is durable and gives a fine, smooth surface. 80. Canvased Hulls.-Canoes and some of the smaller runabouts have canvas stretched tightly over a thin wooden planking. When the pores of the cloth are filled by painting, this material makes a tough smooth skin that will not leak. DECK CONSTRUCTION 81. Decks are constructed or laid in various ways, the principal ones being shown in Figs. 71 to 74. A straight laid Covering Board FIG. 71 deck, Fig. 71, is one where the planks run straight fore-andaft, and the outer ends are nibbed into the oak covering boards, plank sheers, or waterways as they are variously known. A sprung deck, Fig. 72, is one where each plank is bent so that it follows the curve of the side line of the boat and the ends are then nibbed into the FIG. 73 partner plank, or king plank. A taper-laid, or yacht- number of deck planks at each end as there are in the middle, each plank being worked out to a true taper. |