Marine vessel construction

Abstract

A double hull marine vessel is provided which includes a syntactic foam-macrosphere composition between the inner and outer hulls which dissipates force applied to an outer hull.

Description

BACKGROUND OF THE INVENTION1. Field of the InventionThe present invention relates to marine vessels and, more particularly, to a vessel including spaced apart hulls wherein the space between the hulls contains an energy absorbing composition. More particularly, the present invention relates to such a vessel wherein the energy absorbing composition includes hollow microspheres and macrospheres in a resin matrix.2. Description of Prior ArtSpillage of petroleum products, hazardous chemicals or other compositions damaging to the environment resulting from marine vessel hull rupture during grounding, stranding, collision or other accidents has become a major problem. The Oil Pollution Act of 1990 requires that all craft entering United States territorial water have double bottoms and double sides to form an inner hull and an outer hull, traditionally termed a double hull construction. In large marine vessels, the space between the two hulls typically is at least about two meters. The vol...

AI Technical Summary

Benefits of technology

In accordance with the present invention, a double hull construction is provided for a marine vessel which includes an inner hull and an outer hull and a space between the inner hull and the outer hull which is filled with an energy-absorbing composition. The energy-absorbing composition is a syntactic foam comprising a resin matrix and hollow microspheres and which includes hollow macrospheres. As used herein the term, “syntactic foam” means a hardened or curable resin matrix containing small hollow microspheres, such as glass microspheres ceramic or polymeric, e.g., polyvinylidenechloride, phenolic or polyurethane microspheres having a diameter between about 1 and about 300 microns as defined by the ASTM Committee on Syntactic Foam. As used herein, the term, “macrospheres” means low density spheres formed from a resin binder either alone or containing reenforcing fibers such as glass fibers, carbon fibers or the like having a diameter about {fraction (1 / 16)} inch and about 4 inches. The interior volume of the macrospheres contains gas or a low density solid which also contains gas such as a polymeric foam. The macrospheres have a low density of between about 5 and about 40 pounds per cubic feet. The volume percent syntactic foam of the syntactic foam-macrospheres mixture is between about 10 and about 60 volume percent, preferably between about 20 and 40 volume percent while the volume percent macrospheres of the mixture is between about 40 and about 90 volume percent, preferably between about 60 and about 80 volume percent. The syntactic foam functions to provide lower density and strength to the composition positioned between the two hulls. The macrospheres function to provide low density and energy absorbance capacity to the composition.

When the double hull is subjected to an impact force initiated on the outside surface of the exterior hull, the force is transmitted from the exterior into the composition positioned between the hulls and, if the impact force is sufficiently high, the macrosphere in close proximity to the point of impact begin to fracture under the force of the impact thereby absorbing the impact force. When the impact force is sufficiently high, the macrospheres fracture sequentially; first at the most proximate points to the point of initial impact and thereafter sequentially fracturing progressively away from the point of initial impact. Due to macrosphere fracturing, the impact force is dissipated significantly prior to its being transmitted, by way of the hardened resin matrix of the syntactic foam, to the inner hull. Thus, the composition positioned between the two hulls substantially reduces the impact force within the volume between the two hulls. By substantially reducing the impact force prior to the force reaching the inner hull, the probability of the inner hull being fractured is correspondingly reduced or eliminated. In addition, the presence of the hardened syntactic foam provides a physical barrier to the source of the impact force, such as another vessel or a submerged rock formation to prevent it from contacting the inner hull. Accordingly, the syntactic foam-macrosphere composition utilized between the two hulls provides substantial advantages over a hardened syntactic foam or an empty space positioned between the two hulls.

Problems solved by technology

Spillage of petroleum products, hazardous chemicals or other compositions damaging to the environment resulting from marine vessel hull rupture during grounding, stranding, collision or other accidents has become a major problem.

While it is known that double hulls can effectively protect against minor impact forces, it is also known that they are ineffective to withstand strong impact forces.

Such strong impact forces cause both the inner and outer hulls to be breached thereby resulting in spillage of material such as oil from the tank portion of the vessel or of water to allow water ingress into the vessel.

While the use of foam material or hollow beads comprise an improvement over a hollow space between the two hulls to effect absorbance and diffusion of force applied to the outer hull and to reduce force transmission to the inner hull, their use is undesirable since a significant portion of the impact force is transmitted to the inner hull.

Such modules are undesirable since they are subjected to the normal sea forces to which a vessel is subjected resulting in their detachment from the vessel.

Such syntactic foam compositions are undesirable for use between hulls of double hull vessels since they preferentially transmit rather than absorb forces applied to them.

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