Signet Shipbuilding and repair (SS&R), Houston, is currently building two 103’4″x45’6″x15’7″, 299 gt. Robert Allan-Vessels designed for advanced Rotortugs 92-32W built specifically. Signet Sirius i Signet Chapel -to Maritime Seal body to support the Port of Corpus Christi Channel Improvement Project.
With an eye height draft of 24’6, Signet Sirius is 85% complete and will be launched on May 29, with a delivery date of July 2023. Signet Chapel is 65% complete, with a delivery date of November 2023.
“With the ships close to delivery, we have completed the full 3D design and build cycle, and it has significantly improved our shipyard’s production methodology and efficiency,” said Executive Vice President, Administration, Infrastructure and special projects Gayle C. Snyder. “All future ships built at SS&R will follow the same design regime.”
These 92 metric ton (85 reverse) vessel escort/support tugs are the result of years of iterative simulation and design, developed specifically to meet the challenges of escorting very large crude carriers (VLCCs) docked in the Port of Corpus Christi following the completion of the final 54′ channel improvement project. “Increased depth allows harbor vessels to achieve greater cargo drafts, increasing their hull strength and requiring deliberate tug design of this degree to assist,” Snyder said.
The three-propeller Rotortug is designed to increase maneuverability, but is also unique in that the vessel’s travel vector and line tension vector do not have to be aligned, as they must be on a conventional tug or on an ASD tug, which makes it more complex. , effective and efficient maneuvers during the escort of the ship at speed. “That, along with a new generation Markey Machinery The Agile Class III winch package exceeds the design criteria to perform a constant tension vessel escort in a wave period of up to 2 meters 6 seconds as found in the US Gulf of Mexico,” he said Snyder.
The main propulsion comes from three PERSON Marine engines 12V4000 M65L, Tier 4 with a total of 7,725 HP. The network connects to Kongsberg US 205 pitch controllable Z-units containing 2500mm diameter 4-blade nibral propellers in nozzles.
Snyder said that to Signet’s knowledge, the new tugboats are the first towboats to receive an ABS ENVIRO notation, the first in the U.S. to achieve an ABS LEV (low-emission vessel) notation, and the first in the U.S. to receive an ABS Cyber Security Notation-1 (CS-1). “When we started the ships, those claims were true, and we can’t speak to whether other smaller ships had beaten us with shorter deliveries,” Snyder said.
The ship’s service power comes from a level 3 pair John Deere 6135AFM85, generating 300 kW of electrical power each.
“The tugs are built in modules and represent some of the most complex ship structural construction in the United States, with complex geometries of strokes, bedbugs and hull structure for efficient hydrodynamics and escort stability,” Snyder said. “The fundamentals of Markey’s Class III render/recovery winches are integrated into the hull structure reducing weight and increasing escort performance.”
The new tugs will have two winches each: a Markey Machinery DESF-52 AGILE, 200 HP, bow electric winch; and a TESF-32 AGILE electric winch, 200 HP, at the stern.
Also on deck, the tugs are equipped with a Fire extinguishing systems AS (FFS) 1,000 kW SFP centrifugal fire pump and two FFS 1200LB monitors, remotely operated with a flow rate of 10,600 gpm and a range of 400′.
The deposit includes 45,000 gal. fuel oil; 3,500 gals. diesel exhaust fluid; 5,300 gals. potable water; 500 gals. Lubricating oil; and 160 gals. hydraulic oil
“We have also worked extensively with Robert Allan Limited to design to meet intact damage stability standards for all watertight spaces below deck, making the ship survivable for the crew in the event of a breach of the stern or forward propulsion, or from the main engine. room, not required by regulations and difficult to achieve in a vessel of this size, but critical to Signet’s safety standards in the design,” Snyder said.
