Title:
Ship hull
United States Patent 2361409


Abstract:
This invention relates to ship construction and more particularly to hull design. The main object of the invention is to provide a boat or ship hull of high efficiency and strength but of simple form and therefore of low cost. As a general rule, in marine design, complication in hull construction...



Inventors:
Gordon, Munro
Application Number:
US51256543A
Publication Date:
10/31/1944
Filing Date:
12/02/1943
Assignee:
Gordon, Munro
Primary Class:
Other Classes:
114/61.3, 114/63, 114/140
International Classes:
B63B3/00
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Description:

This invention relates to ship construction and more particularly to hull design.

The main object of the invention is to provide a boat or ship hull of high efficiency and strength but of simple form and therefore of low cost.

As a general rule, in marine design, complication in hull construction has been justified to some degree by improved performance secured by the thus constructed hull. But construction costs increase so rapidly with complication in design that performance has almost always been sacrificed to some extent when cost was an essential factor, as is usually the case.

My invention provides a hull form which.gives highly efficient performance but in which complications in building construction are minimized, and costs thereby reduced.

To this end, my hull is a combination hull and is based upon the utilization of a substantially flat-bottomed hull, or variant thereof, supplemented by a complementary construction in the form of an added lower hull designed to overcome the performance deficiencies of simple flat-bottomed hulls, particularly forward, where entrance characteristics are of predominating importance.

In my construction, such desirable entrance characteristics are produced without sacrificing under-water performance of the submerged portion of the hull. In fact my construction permits the application of independent Surface and submerged design techniques aft of the entrance portion as will be hereinafter explained.

Secondly, my lower hull is of substantial crosssectional depth and stiffness, and extends fore and aft for such distance that it provides sufficient strength to prevent sagging and hogging. Costly details of keelson or deadwood construction are thus obviated.

Features of my hull may be more readily understood by reference to the accompanying drawing illustrating a preferred example of my invention, in which: Fig. 1 is a side elevation of a hull embodying my invention; Fig. 2 is a bottom plan view thereof; Fig. 3 is an enlarged cross-sectional view indicating the exterior contour of the hull along the line 3-3 of Fig. 1; Fig. 4 is a similar enlarged cross-sectional view indicating the contour of the hull along the line 4-4 of Fig. 1, and Fig. 5 is a still further enlarged cross-sectional view taken along the line 5-5 of Fig. 1, and illustrates certain construction details.

As shown by the drawing, my hull is a combination hull formed of two component parts, an upper hull I and a lower hull 2. The upper hull I has a substantially flat bottom 6 and is suitably shaped longitudinally, as shown in Figs. 1 and 2, to distribute the displacement of water as desired. A preferred form of curvature of the sides 7 is illustrated in the drawing although this curvature may be increased or decreased as desired or, for the purposes of simplicity and economy, the curvature may be eliminated to form a substantially straight line contour from the chine to the sheer or deck line. The deck 8 of upper hull I is shown as cambered though in some constructions it may be flat in cross-section.

Unsatisfactory performance of the flat-bottomed upper hull I is overcome by combining with the upper hull a simply constructed lower hull 2.

The hull 2 extends from the stem aft a distance preferably substantially equivalent to the waterline length of the combination hull and, in any event, to some point abaft midships and abaft the maximum beam of the upper hull. The lower hull 2 is of such form that it may be combined with the substantially flat bottom of the upper hull along a line of juncture 11 which may be and preferably is substantially a straight line athwart the ship throughout the length of the juncture.

The forward end of such juncture is adjacent the forward end of the load water-line (indicated by dots and dashes) and may be above it (as shown in Fig. 1), or at or below the same.

As illustrated in Fig. 2, the maximum beam of the lower hull 2 is at a point forward of the maximum beam of the upper hull 1, and tapers forward of this point to a stem line forming a continuation of the upper hull stem line 10 from a point just above the water-line. The lower hull 2 is so shaped that its upper side edges merge with, and become coincident with a substantial length of, the upper hull chine lines. In the form shown in the drawing, the upper hull is flared forward and the forward side portions of the lower hull continue in fair curves the flare of the upper hull. In this particular case, highly desirable entrance characteristics are secured.

In order, however, to prevent the lower hull 2, aft of the forward portion, from detracting from performance of the combination hull, its maximum beam, as has been previously stated, is carried forward of the point of maximum beam of the upper hull, and it is streamlined aft in order to offer the least possible resistance to its passage through the water. Furthermore, while the exterior cross-sectional contour of the lower hull forward is substantially trapezoidal, as indicated by Figs. 3 and. 4, for the major portion of its length aft its side portions become substantially vertical, as indicated at 15 in Fig. 5, providing substantially rectangular cross-sectional contours. This box-like straight-sided, flat bottomed construction is the simplest type of construction whether the lower hull be made of metal or wood.

As will be readily seen, the sidings of the two hulls are designed independently of each other aft of the entrance area and consequently the upper hull may be designed for pleasing appearance and best surface performance while the lower hull may be independently designed for best submerged performance. By utilizing the water-exposed under-portions 6 of the upper hull as part of the bottom of the combination hull, the under-water portion of the lower hull 2. can be of relatively narrow beam thus offering minimum resistance to the passage of the hull through the water.

The parts I and 2 may be attached together in accordance with established engineering principles and according to the particular materials of which the two hulls are made. For instance, as shown in Fig. 5, the upper hull 1, deck planking: 8, deck beams 16, frames 17, and side planking 7 are formed of wood, while bottom frames 19, bottom plating 6, chine angles 21, and gussets 18 are formed of steel to provide a composite construction.

The lower hull 2 is likewise formed of steel having welded reinforcing plates 22, and may be welded to the bottom steel plating 6. In the case of such construction, bulkheads 12, 13, and 14, indicated in Fig. 1, may be welded at suitable intervals in order to form oil-tight compartments useful as fuel tanks. The upper hull and lower hull conveniently may be independently constructed and then combined after their construction as separate units. This affords more rapid and easier working conditions, which also tend to reduce cost.

While I have shown the lower hull developed aft into a skeg 2l0, it will be understood that other forms of sections aft of midships or aft of the point of maximum beam of the upper hull may be substituted. The lower hull, because of its substantial depth and because of its position extending at least the major portion of the waterline length of the combination hull, imparts a longitudinal rigidity sufficient to withstand stresses whether afloat or ashore and permits elimination of any reinforcement in the form of deadwood along the median line of the upper hull.

As a result, the bottom frame angle irons 19 may be uninterrupted centrally. This eliminates complications of:fitting and labor usually encountered in keelson or deadwood construction.

As will be readily understood, the invention can be incorporated in boats and ships of widely different size and type and of various forms of construction, including hydro-airplanes and pontoons.

I claiTm: 1. A ship hull having, in combination, an upper hull, and a lower:hull extending fore and aft a distance equivalent to a major portion of the water-line length of the ship, the cross-sectional juncture between said hulls athwart said ship being substantially a straight line throughout the length of said juncture, said lower hull tapering aft and forward of its maximum beam, with upper edges of the forward side portions of the lower hull generally'following the chine lines of said upper hull, and with said lower hull forward side portions conforming in general with forward side portions of the upper hull, thereby providing desirable entrance characteristics for the combination hull, and said lower hull side portions being carried aft of said fairing portion independently of said upper hull side portions, thereby permitting independent lower hull submerged and upper hull surface design aft of said forward fairing portion.

2. A ship hull having, in combination, an upper hull, and a lower hull extending fore and aft a distance substantially equivalent to the waterline length of the ship, the cross-sectional juncture between said hulls athwart said ship being substantially a straight line throughout the length of said juncture, said lower hull having its maximum beam forward of the maximum beam of said upper hull and tapering aft and forward of its maximum beam, with upper edges of the forward side portions of the lower hull generally following the chine lines of said upper hull, and with said lower hull forward side portions conforming in general with forward side portions of ;25 the upper hull, thereby providing desirable entrance characteristics for the combination hull, and said lower hull side portions being carried aft of said fairing portion independently of said upper hull side portions, thereby permitting in,0 idependent lower hull submerged and upper hull surface design aft:of said forward fairing portion.

3. A ship hull having,,in combination, an upper hull, and a lower hull extending above the water:35 .line of the combination hull forward and extending aft to a point abaft midships, the crosssectional juncture between said hulls athwart said ship being substantially a straight line throughout the length of said juncture, said lower hull tapering aft and forward of its maximum beam, with upper edges of-the forward side portions of the lower hull generally following the chine lines of said upper hull, and with said lower hull forward side portions conforming in general with for-5 .ward side portions of the upper hull, thereby providing desirable entrance characteristics for the combination hull, and said lower hull side portions being carried aft of said fairing portion independently of said upper hull side portions, 5 thereby permitting independent lower hull submerged and upper hull surface design aft of said forward fairing portion.

4. A ship hull having, in combination, a substantially flat-bottomed upper hull having side portions tapering to a stem line, and a lower hull substantially flat-bottomed throughout a major portion of its length extending fore and aft a distance substantially equivalent to the water-line length of the ship, said lower hull having an exterior contour substantially rectangular in cross-section athwart the ship from its point of maximum beam aft and substantially trapezoidal in cross-section athwart the ship from said point forward, with upper edges of the forward side portions of the lower hull merging and becoming coincident with the chine lines of said upper hull, and with said lower hull forward side portions Jairing together with forward side portions of the upper:hull and tapering to a line forming a continuation of said upper hull stem line, thereby providing desirable entrance characteristics for the combination hull, and said lower hull side portions being carried aft of said fairing portion independently of said upper hull side portions, thereby permitting independent lower hull submerged and upper hull surface design aft of said forward fairing portion.

5. A ship hull having, in combination, a substantially flat-bottomed upper hull having side portions tapering to a stem line, and a lower hull substantially flat-bottomed throughout a major portion of its length, said lower hull having its maximum beam forward of the maximum beam of said upper hull and having an exterior contour substantially rectangular in cross-section athwart the ship from its point of maximum beam aft and substantially trapezoidal in crosssection athwart the ship from said point forward, with upper edges of the forward side portions of the lower hull merging and becoming coincident with substantial lengths of the chine lines of said upper hull, and with said lower hull forward side portions fairing together with forward side portions of the upper hull and tapering to a line forming a continuation of said upper hull stem line, thereby providing desirable entrance characteristics for the combination hull, and said lower hull side portions being carried aft of said fairing portion independently of said upper hull side portions, thereby .permitting independent lower hull submerged and upper hull surface design aft of said forward fairing portion.

6. A ship hull having, in combination, an upper hull having metal bottom plating, and a lower metal hull extending fore and aft a major portion of the water-line length of the ship and welded to the upper hull, the cross-sectional juncture between said hulls athwart said ship being substantially a straight line throughout the length of said juncture, said lower hull having its maximum beam forward of the maximum beam of said upper hull and tapering aft and forward of its maximum beam, with upper edges of the forward side portions of the lower hull merging and becoming coincident with the chine lines of said upper hull, and with said lower hull forward side portions fairing together with forward side portions of the upper hull, thereby providing desirable entrance characteristics for the combination hull, and said lower hull side portions being carried aft of said fairing portion independently of said upper hull side portions, thereby permitting independent lower hull submerged and upper hull surface design aft of said forward fairing portion.

GORDON MUNRO.