L.W.L. HALF-BREADTH PROPORTIONS

1

ship to the prismatic coefficient which varies with p and is equal

to

to where p ranges from .60 to .82, respectively.

p p .92 .99

By determining the value of the bilge diagonal coefficient “0," and referring to the diagram opposite, the offsets for a line enclosing an equivalent area may be taken off and run as a half-breadth line.

9

96

7th. The load water line and bilge diagonal half-breadths having been preliminarily faired, may be lifted off on a slip of paper and transferred to body plan construction lines, when there should be no difficulty in drawing in freehand the sections, having the "dead flat" section as one extreme, guiding curve and the transom frame as the other.

8th. After the preceding sections have been carefully outlined

2

heights on which to set off the rail half-breadths previously run in plan, as described in paragraph 4. This will enable the completed body plan to be drawn in approximately, from which spots may be obtained to fair up.

Having got thus far, the final work of fairing will be a comparatively easy matter. A buttock line half-way out on the counter will prove a very useful line for this purpose, thereafter taking buttock and water line alternately until the whole body is faired. Where great fairness is required, a complete set of diagonal lines should be run; but ordinarily this is unnecessary, unless in small craft where the sections are intended directly for the floor without further fairing.

The following will prove a suitable method for designing and fairing the bossed plating enclosing after-end of shafting. Having determined the outside diameter of the boss of spectacle frame, lay off the distance to outer edge of boss barrel at forward end of same on the half-breadth plan, as at A. Then take another spot at the fore end of the stern tube equal to the siding of the vessel's bulkhead frame plus one inch clear of the stuffing box flange on the stern tube bulkhead at "C." Through these two spots continue a straight line until it intersects the water plane at the shaft center level "D." The angular space formed by the junction of

the water plane mentioned and the projected line should then be carefully faired into the eye with a spline, when the resulting line will give you half-breadths at the shaft center height. These halfbreadths being transferred to the body plan, radii should be struck through them giving the contour of the bossing, which may be continued freehand into the frame sections above and below the boss, observing that the general tone harmonizes with the outline of spectacle frame previously drawn in, in accordance with the form advocated under that heading.

Having outlined the form of bossing on body plan, three diagonal lines should be struck, the lower one intersecting the arcs forming oxter under spectacle frame, the middle one through the

center of shaft, as shown to diagonal 11, and the other making a like intersection with the curves of the slope, as shown on the diagram. These diagonals may now be lifted off and run in the

usual way on half-breadth, faired up, and retransferred to body plan, thus permitting of same being more accurately delineated, as it will be remembered these were originally drawn freehand.

A