Self propelled dynamically positioned reel pipe laying ship

A reel pipelaying ship, having forward, midship, and stern sections, and baseline, tank top, and main deck levels, comprising:

• port and starboard side outer substantially longitudinal hull members and port and starboard side inner longitudinal bulkheads, each extending substantially the length of the ship, said hull members and bulkheads extending vertically at least between the baseline and main deck levels in the forward and stern sections and, in the midship section, substantially above the main deck level;
• port and starboard side substantially horizontal transverse midship structural members extending between the top portions of the raised midship sections of said outer hull members and inner longitudinal bulkheads;
• at least one port and starboard side intermediate substantially horizontal transverse member extending between said outer hull members and inner longitudinal bulkheads and vertically spaced between said tank top and midship structural members wherein the midship portions of said outer hull members and inner longitudinal bulkheads, transverse midship structural members, and the at least one intermediate transverse member together comprise a reel support structure;
• and
• bearing means for rotatably mounting a pipe-carrying reel to said reel support structure such that the load of the reel is distributed downwardly and outwardly, both longitudinally and transversely through the ship to maintain the stress on primary structural members of the ship within allowable stress limits for the materials used in the construction of said primary structural members.

A reel pipelaying ship having forward, midship, and stern sections, and baseline, tank top, and main deck levels, comprising:

• a hull composed of a plurality of longitudinal port and starboard side primary sturcural members;
• port and starboard side reel support structures, each having a substantially box-beam cross-section extending upwardly from said port and starboard side primary vessel structural members and above the main deck level of the ship in the midship section thereof to increase the section modulus of the ship in the midship section;
• a pipe-carrying reel;
• bearing means for mounting the reel for rotation about a substantially horizontal axis across the ship's beam;
• and
• bearing support means mounting the bearing means to the respective reel support structures and distributing the load of the reel downwardly and longitudinally outwardly through said reel support structures and primary ship structural members to maintain the stress on the ship's primary structural members within the maximum allowable stress limits for the materials used in the construction of the ship's primary structural members.

A reel pipelaying ship having forward, midship and stern sections, comprising:

• port and star board side reel support structures, each having a substantially box-bean configuration and located at a substantially midship portion of the ship on and above the main deck level to a height sufficient to accommodate the largest permitted reel diameter, based on maximum pipe diameter and length to be carried by the ship;
• a pipe-carrying reel rotatably mounted to said reel support structure about a substantially horizontal rotational axis extending transversely across said ship, said reel having a shaft, a pair of flanges spaced from each other and extending radially outward from the shaft, and a hub coaxial with the shaft and disposed between the flanges and containing at least one ballast compartment;
• and,
• means coupled to said reel for supplying ballast into said at least one ballast compartment in the hub and for venting the interior of the ballast compartment as ballast is supplied thereto.

A self-propelled reel pipelaying ship, having forward, midship, and stern sections, and baseline, tank top, and main deck levels, comprising:

• port and starboard side outer substantially longitudinal hull members and port and starboard side inner longitudinal bulkheads, each extending substantially the length of the ship, said hull members and bulkheads extending vertically at least between the baseline and main deck levels in the forward and stern sections and, in the midship section, substantially above the main deck level;
• port and starboard side substantially horizontal transverse midship structural members extending between the top portions of the raised midship sections of said outer hull members and inner longitudinal bulkheads;
• at least one port and starboard side intermediate substantially horizontal transverse member extending between said outer hull members and inner longitudinal bulkheads and vertically spaced between said tank top and midship structural members wherein the midship portions of said outer hull members and inner longitudinal bulkheads, the transverse midship structural members, and the at least one intermediate transverse member together comprise a reel support structure;
• bearing means for rotatably mounting a pipe-carrying reel to said reel support structure such that the load of the reel is distributed downwardly and outwardly, both longitudinally and transversely through the ship to maintain the stress on primary structural members of the ship within allowable stress limits for the materials used in the constructionof said primary structural members;
• and
• drive propellers mounted to drive shafts extending through the hull bottom;
• wherein the ratio of the diameter (d) of the propellers to the distance (H) from the mean water line of the ship to the center of the prop is in the range of from about 0.625:1 to 1.125:1 between high and low draft conditions, respectively.

A self-propelled reel pipelaying ship having forward, midship, and stern sections, and baseline, tank top, and main deck levels, comprising:

• a hull composed of a plurality of longitudinal port and starboard side primary structural members;
• port and starboard side reel support structures, each having a substantially box-beam cross-section extending upwardly from said port and starboard side primary vessel structural members and above the main deck level of the ship in the midship section thereof to increase the section modulus of the ship in the midship section;
• a pipe-carrying reel;
• bearing means for mounting the reel for rotation about a substantially horizontal axis across the ship's beam;
• bearing support means mounting the bearing means to the respective reel support structures and distributing the load of the reel downwardly and longitudinally outwardly through said reel support structures and primary ship structural members to maintain the stress on the ship's primary structural members within the maximum allowable stress limits for the materials used in the construcution of the ship's primary structural members;
• and
• drive propellers mounted to drive shafts extending through the hull bottom;
• wherein the ratio of the diameter (D) of the propellers to the distance (H) from the mean water line of the ship to the center of the prop is in the range of from about 0.625:1 to 1.125:1 between high and low draft conditions, respectively.