Cover Plate Construction for Boat Decks

This invention relates generally to removable cover plate constructions for installation in the decks of boats, and more particularly to constructions employing threaded cover plates which can be readily installed or removed to provide quick access to areas below the deck such as a storage space, the bilge, and areas where shut-off valves, instruments, and the like are located. Where such plates were employed with instrument gauges, the plates were sometimes constituted of transparent material such that the gauges could be read with the cover plate still in place.

In the past a number of deck cover constructions employing a deck fitting and a cooperable closure member have been proposed and produced, and have met with varying degrees of success. Several problems were encountered, however, with the prior art constructions. Where the closure member and the deck fitting had cooperable threads of conventional construction, there was a likelihood of binding of the two parts in the event that either became warped. When the parts were constituted of molded plastic, a limited amount of such warping was inevitable as the plastic cured. The deck fitting part, being generally of annular configuration, sometimes assumed a slightly egg-shaped configuration, causing interference or a poor fit between the threads, and resulting in binding as the closure member was screwed in place.

The deck fitting part usually had an apertured annular mounting flange by which it could be screwed in place on the deck. In the event that the latter was not perfectly flat or planar, but instead slightly skewed, the fitting tended to follow this contour, thereby assuming a bowed configuration. This also caused interference problems with the cooperable threads. In addition, it was usually considered important to provide a good sealing surface on the closure part that was engageable with the cooperable surfaces of the deck fitting. When the latter was bowed, such surfaces did not meet uniformly at all points around the periphery of the closure, resulting in a poor fit and the likelihood of leakage of water past the cover and into the area beneath the deck.

There were also cost disadvantages involved in providing, on such fittings, threads extending beyond 360.degree. in spiral circumference, since the provision of such threads made molding of the parts difficult. A suitable location for a parting line in a pair of mold cavities is often difficult or impossible to find when it is desired to mold each of the parts in a single step or operation. In addition, where relatively small gauge threads were involved, there was a likelihood of large grains of sand or dirt becoming lodged in the areas around the threads, resulting in undesirable binding or seizing thereof.

The above drawbacks and disadvantages of prior access cover plate constructions for boats are obviated by the present invention, which has for an object the provision of a novel and improved access cover construction which is both simple in its structure and reliable in operation over extended periods of use and under adverse conditions.

Yet another object of the invention is the provision of an access cover as above, wherein the parts are constituted mostly of molded plastic and wherein a highly leak-resistant seal is obtainable even in the event that the parts undergo a slight warping due to curing of the plastic, or due to slight imperfections in the deck of the boat with which the cover is used.

Still another object of the invention is the provision of an improved access cover construction wherein the individual parts can each be molded as a single integral piece, in simple cavities and at low cost.

A further object of the invention is the provision of an improved access cover construction wherein the likelihood of binding of the parts is greatly minimized, and wherein the chance of particles of sand or dirt becoming lodged in the cooperable thread formations of the parts is substantially reduced.

The above objects are accomplished by the provision of a threaded access cover plate construction for the deck of a boat, comprising a novel deck fitting and means thereon, engageable with the deck for securing the fitting thereto in sealing relation therewith, together with a unique screw closure that is receivable in the deck fitting. The screw closure and fitting have cooperable, mating buttress-type threads which are engageable when the closure is screwed into the fitting. The fitting includes a rim which is engaged by a centering shoulder on the closure. The threads are so dimensioned as to provide excessive slop and looseness between the fitting and closure, so as to enable lateral shifting of the closure to occur when it is screwed into the fitting. By virtue of such lateral shifting, the centering shoulder can precisely seat into the rim of the fitting regardless of the relative positions of the threads, thus insuring an adequate seal even in the event that a slight warping or distortion of the fitting has occurred.

Other features and advantages will hereinafter appear.

In the drawings, illustrating a preferred embodiment of the invention:

FIG. 1 is a vertical section of the improved threaded access cover plate construction of the present invention, comprising a deck fitting and a screw closure received therein.

FIG. 2 is a top plan view of the cover plate construction of FIG. 1.

FIG. 3 is an enlarged fragmentary section of a portion of the cover plate construction of FIG. 1, particularly showing the thread forms and sealing means associated therewith.

FIG. 4 is a fragmentary bottom plan view of the deck fitting part per se, of the cover plate construction of FIG. 1.

Referring to FIGS. 1 and 3 and in accordance with the present invention there is provided a novel and improved access cover plate construction for the deck of a boat, generally designated by the numeral 10 and comprising an annular deck fitting 12 and a circular screw closure 14 receivable in the fitting. The fitting 12 comprises a tubular body 16 which is adapted to extend into a hole in the deck, and an annular mounting flange 18 engageable with the upper surface of the deck surrounding the hole.

As shown in FIGS. 3 and 4, the mounting flange 18 has a series of circumferential ribs 20 on its underside, and multiple mounting holes 22 to receive wood screws (not shown) which secure the fitting to the deck. Suitable sealing compound can be applied to the underside of the flange, over the ribs, and the fitting then installed to provide a water-tight seal with respect to the deck.

In accordance with the present invention there is provided a novel sealing arrangement between the screw closure and deck fitting, involving a centering shoulder on the closure and the provision, on both parts, of cooperable buttress-type threads so dimensioned as to provide a relatively loose fit which permits limited self alignment of the closure to occur as the latter is tightened. In accomplishing the seal, the fitting is provided with an annular sealing rim or lip 24 (FIG. 3) which is adapted to be engaged by the centering shoulder of the closure, indicated by the numeral 26. The shoulder is preferably, but not necessarily, conical in shape.

The cooperable buttress-type threads are indicated by the numerals 28 and 30. As shown in FIG. 3, they have corresponding helical surfaces of engagement wherein the axes of the helices are coincident with one another and with the axes of both the closure and the fitting. In addition, there is provided a substantial amount of slop and looseness between the threads of the two parts such that as the closure is screwed into the fitting, it can shift laterally of its axis as determined by the engagement of the centering shoulder 26 of the closure and the rim 24. In particular, FIG. 3 illustrates that the diameter of the external thread 28 at its root 32 is significantly less than the diameter of the internal thread 30 at its crest 34. Similarly the diameter of the external thread 28 at its crest 36 is seen to be significantly less than the diameter of the internal thread 30 at its root 38. The resulting clearance spaces give rise to the capability of the closure to undergo the lateral shifting mentioned above, as the closure is tightened.

Such a construction has been found to be very effective in establishing a primary seal between the rim 24 and shoulder 26. In the event that the mounting flange 18 has been slightly distorted by virtue of its being screwed down to a non-planar or warped section of the deck, the particular self-centering configuration of the shoulder 26 effects a proper, optimum positioning of the closure to compensate for such a condition. In the event that one or both of the sealing surfaces 24 or 26 are slightly out of round, following curing, the above construction has been found to minimize the adverse effects resulting therefrom. Accordingly the likelihood of undesirable leakage is greatly reduced. In addition, there are eliminated other problems associated with binding of threads due to distortion of one or both of the cooperable threaded parts, resulting either from improper curing or from stress due to installation of the fitting on the deck surface.

Further in accordance with the present invention, the thread 30 of the fitting is constituted as a single helix extending through an angle of just under 360.degree.. The beginning and the end of the thread are particularly shown in FIG. 4, and designated 40, 42 respectively. The provision of a single thread makes possible the molding of the fitting in a single two-part cavity, with the parting line extending through the crest of the thread 30 from its beginning 40 to its end 42. Reduced manufacturing cost is thus realized. In addition, by the provision of a single buttress-type thread 40 there is a relatively small area of engagement thereof with the closure thread 28. Accordingly, there is greatly minimized the likelihood of undesirable binding of the threads, due to sand or dirt becoming permanently trapped therebetween, or due to the formation of salt crystal deposits on the threads. Smoother operation and virtually complete freedom from seizure thereby result. Moreover, where the single helical thread is carried by the fitting which is secured to the deck, there is encountered less difficulty in keeping the thread clean, since there are no "grooves" between adjacent thread crests, in which dirt can become trapped. Accordingly, any foreign matter which does become lodged in the vicinity of this single thread can be quickly wiped away with a cloth or towel. On the other hand, the closure part can still be provided with a multiple thread, since it is more readily accessible due to the fact that it can be completely removed from the deck fitting, and any foreign matter thereafter wiped or brushed away, as required.

Further in accordance with the invention there can be provided an optional secondary seal between the closure 14 and the fitting 12. In accomplishing this the latter has an annular peripheral groove 44 in which there is received a resilient sealing gasket 46. The gasket is adapted to be engaged and somewhat flattened by a peripheral sealing surface 48 on the closure when the latter is tightened. The amount of distortion of the gasket is limited somewhat by the engagement of the shoulder 26 and rim 24. Accordingly, excessive flattening of the gasket does not occur; such flattening otherwise might adversely affect the sealing capability of the gasket, since excessive deformation thereof might conceivably give rise to the taking of a "set".

As particularly illustrated in FIGS. 1 and 2, on the closure there are provided means defining a pair of finger engageable notches 52, 54 to facilitate grasping the closure during opening or closing movement. Also, extending downward from the closure is an integral stiffening rib 56, for added rigidity and strength.

In addition to the advantages of smoothness of operation and freedom from binding mentioned above, the present construction enjoys the advantage of low overall cost, since the deck fitting 12 can be molded of plastic as a single integral piece, the same being true of the closure 14. The gasket 46 may take the form of a simple O-ring as shown, and can be merely pressed into place following curing of the fitting. Also, installation can be readily accomplished, all without the need for special tools, skilled personnel, or the like.

The device is thus seen to represent a distinct advance and improvement in the technology of boat accessories.

Each and every one of the appended claims defines a distinct aspect of the invention separate from the others, and each claim is accordingly to be treated in this manner when the prior art devices are examined in any determination of novelty or validity.

Variations and modifications are possible without departing from the spirit of the invention.