Spiling battens may be used to determine the shape of either one or both edges of a plank and the principles of taking the spiling are the same in each case.

Fore and after hoods of the first garboard strakes are generally ordered wider than the balance of the strakes so that they may be spiled to fit. If this was not done it would not only require very heavy edge set to bring the hood ends down to the rabbets, but would throw a hump in the planking edge abaft the stem and forward of the stern post that would increase the difficulty of setting the next strake.

One method of taking a garboard forehood spiling is detailed in Figs. 159 and 160. The liner first runs in the line of the upper edge of the garboard, being careful to keep within the limits required by the available width of stock ordered for this piece. A thin wide spiling batten is then roughed out to clear both the rabbets and the line, and tacked in its natural position, as shown in the figure.

Then set a compass, or divider, at such radius as to permit the scribing of a good portion of a circle on the batten when the center point is held on either the line of the upper edge of the garboard or the inner rabbet line. With the compass or divider so set, scribe arcs on the batten as shown in the figure, at frequent intervals. Where the curvature is sharp they should be scribed very close together.

The batten is next taken off the ship and laid on the timber from which the forehood is to be cut. If the fore-hood is to be fitted without edge set the batten will be permitted to lay in its natural position in marking out the piece. If, however, the top edge of the garboard is to be left straight, it is most likely that the forward end of the batten will have to be sprung up to fit it. The amount of spring necessary to make the batten fit the straight upper edge of the hood will be the same as the amount of edge set required to fit the forehood in place on the ship if the upper edge is left straight. If this is excessive in the opinion of the liner some of the spring is taken out of the batten, and the upper edge of the garboard will then be cut with some curvature.

To scribe the points off the batten onto the hood timber, the compasses or dividers are used with the same radius as when the batten was scribed from the ship, the center point being set first at one point on the arc, then at another point about 90 degrees from the first, and short arcs drawn so that they will cross as shown in the figure. When the batten is sprung up to fit the straight upper edge of the garboard, the arcs at the top must cross directly on the edge of the timber. The balance of the points are then marked oft with the batten held in this position. It will thus be seen that with the same spiling batten, it is possible to lay out the garboard forehood with either no edge set, or the full edge set required by leaving the upper edge of the garboard straight, or any intermediate desired edge set, according to the conditions, width of available stock, and the liners judgment.

Figure 155. Showing Spiling Batten In Place On Ship (Port Side).

Figure 160. Showing Method of Marking out Garboard Forehood From Spiling Batten.

The after end of the batten should in any of the above conditions, be placed on the timber so that its upper scribe marks fit, or are parallel to, the upper edge of the timber. This end is then held in this position whether or not the forward end is sprung from its natural position. The width of the garboard at the point A is also generally made the same as the balance of the strake.

It should be noted in Fig. 160 that the cutting line indicates the shape of the faying side of the hood to fit the inner rabbet, and that, as the batten is scribed, the cutting line will appear on the outer face of the hood. The rabbet bevels therefore have to be taken and proper allowance made for them in establishing the corrected cutting line. The corrected line will generally be slightly outside of the first scribed line, the bevels reading under so that after the hood is cut, the lower inner corner will correspond to the first scribed line and will fit the inner rabbet. The bevels are taken in much the same manner as ceiling bevels, except that a calking seam is provided. This simply means that the bevel run on the edge of the hood is slightly less than that taken from the rabbet.

The rabbet on the keel, as it approaches the stem and stern post is gradually reduced, or tapered, in its depth, so that at the stem and stern post it will be only as deep as required by the top side planking. Hence fore and after hoods of the garboards must in all cases be tapered off in thickness to fit the rabbet. Since the after end of the fore hood and the fore end of the after hood must be the same thickness as the balance of the strake amidships, there is often a great deal of material to be taken off in thinning the hood ends. Very often the taper in thickness is cut with as much twist as the original thickness of the timber will permit, this twist being in the direction that the hood will have to be twisted in forcing it to its place. This reduces the amount of twist that the timber must stand and decreases by that much the difficulty of getting the hoods in place.

All planking which has to be bent, twisted, or edge set must be thoroughly steamed.

The bevels for the edges of the planking may in general be lifted in the same manner as has been p eviously described for ceiling bevels, except that it will not be found necessary to reverse them to obtain a surface for scribing the cutting line. This may be explained another way by stating that wherever the extreme breadth of either ceiling or planking is utilized, the bevels as taken from the ship must be converted into standing bevels, or the cutting line would appear on the extreme edge of the timber and could not be defined. Since planking bevels as taken from the ship are already standing, or where under, are at a point not using the full width of the plank, it is not necessary to reverse them.

The allowance for the calking seam is generally made when the bevels are lifted from the ship. It is customary in most yards to allow an opening not to exceed ⅛ inch at the outside face of the planking.