Vessel having an improved hull shape

Abstract

This relates to vessels in general, but in particular to vessel designed to be exposed from low to medium to high waves. Both for comfort of persons, animals or fragile goods, steady sailing is preferred, without causing the waves slamming in on the vessel hull or excessive pitching of the vessel. This is also the case for service and supply vessels performing operations in relation to offshore or subsea installations. To obtain a solution to the aforementioned issues the present invention provides a vessel, wherein a stern ( 11 ) of the vessel extend below a design waterline (Tdwl), and wherein opposite side faces ( 14,15 ) of the stern ( 11 ), when seen in an opposite direction of the vessels primary sailing direction, form an acute angle under and above the design waterline (Tdwl) to decrease the vessels displacement in the rear end and are adjoined along at a line of symmetry forming a stern centerline (CL).

1 . A displacement type vessel comprising a rear end arrangement for reducing wave impact loads on the vessel, which rear end consists of the part of the vessel backwards from the vessel's midship mark, when seen in the vessels primary sailing direction, and which vessel has a transversely symmetrical hull shape about its center line, and a vessel bottom of the rear end arrangement conforms to an engine driven propulsion system, wherein a stern of the vessel extends below a design waterline, wherein opposite side faces of the stern, when seen in an opposite direction of the vessels primary sailing direction, form an acute angle under and above the design waterline so as to decrease the vessels displacement in the rear end, the opposite side faces being adjoined along at a line of symmetry forming a stern centerline, wherein the stern centerline of the vessel above the design water line has a non-concave shape and is sloped forwards in the vessels primary sailing direction, and wherein frame lines of the stern are outwardly sloping from the design water line and run upwards in a convex-like shape gradually back towards the center line thereby providing side faces of the stern having a substantially convex configuration, so as to provide a decreasing buoyancy increase in the upward direction of a the stern in combination with the shape of the centerline of the stern. 
     
     
         2 - 12 . (canceled) 
     
     
         13 . The vessel according to  claim 1 , wherein the centerline of the stern rises and has a substantially increasing curvature in the forward direction of the vessel in a lower part of the stern and in an upper part continues to rise with a substantially diminishing curvature. 
     
     
         14 . The vessel according to  claim 1 , wherein the centerline of the stern is arranged with one or more sections, which are straight. 
     
     
         15 . The vessel according to  claim 1 , wherein a spray board arranged in an uppermost part of the stern is extending outwards from the stern. 
     
     
         16 . The vessel according to  claim 1 , wherein at an upper portion located above midway between the design waterline and the top of the stern, the vessel has flare angles of the stern that are in the range of 5-50 degrees relative to a vertical direction. 
     
     
         17 . The vessel according to  claim 1 , wherein a curvature of the stern centerline located at an upper part of the stern increases from 0 degrees to 60 degrees in an upward direction relative to a vertical direction. 
     
     
         18 . The vessel according to  claim 1 , wherein the hull below the design waterline forms a bend or knuckle between a bottom of the hull and the stern, which bend or knuckle is of a smaller curvature than a lowest curvature of the centerline of the stern. 
     
     
         19 . The vessel according to  claim 1 , wherein the vessel comprises a foreship arrangement, which foreship arrangement consists of the part of the ship in front of the vessels midship mark, when seen in the vessels primary sailing direction, and which vessel has a transversely symmetrical hull shape about its center line and a substantially conventional form below its design water line, wherein a centerline of a bow of the vessel by the design water line is curved backwards in the vessels primary sailing direction, and wherein a shape of the bow is outwardly sloping from the design water line so as to create at least a lower portion of the bow, which is concave, and wherein the shape of the bow runs upwardly in a curved shape, which gradually runs back towards the center line of the vessel so as to create an upper portion, which is convex, and which provides a decreasing buoyancy increase, in the upward direction of a major part of the bow, by a combination of the curvature of the centerline of the stern and the shape of the stern. 
     
     
         20 . The vessel according to  claim 19 , wherein the vessel bow comprises a bulbous bow below the design water line, or a knuckle or beak above the design water line . 
     
     
         21 . The vessel according to  claim 1 , further comprising a helicopter platform on the vessel.