While the US Navy goes back to using hydraulic deck machinery for its reliability, one manufacturer is using digital twins to improve equipment performance
After enduring performance issues with electric-driven deck machinery, the US Navy went back to ordering hydraulic winch systems when it contracted US shipyards to build a new fleet of service tugs.
As a milestone in this campaign, the first of a series of six new Z-Tech 4500 tugs (YT-808 series) was successfully launched by Dakota Creek Industries of Anacortes, in Washington state, at the end of May 2020. This was built to a Robert Allan Z-Tech 4500 design with hydraulic deck equipment supplied by JonRie InterTech.
These tugs have an overall length of 27.4 m, moulded breadth of 11.7 m, hull depth of 5 m and navigational draught of 4.9 m. Twin Caterpillar 3512E 1810 HP main engines drive Schottel SRP 340 fixed pitch Z-drive thrusters providing each YT-808 tug with 40 tonnes of bollard pull.
Deck machinery on these tugs will be hydraulic driven, with a JonRie InterTech-designed and supplied hydraulic power unit, rated at 56 kW, installed in the engineroom.
“US Navy had so much equipment in service not working it was time to fall back and regroup,” says JonRie InterTech president Brandon Durar. “The Navy went back to what they call legacy equipment that works.
“When we won the contracts for the Navy YT-808 class tugs, the project started out with electric winches, but to be similar to the YT-802 class tugs, the Navy went back to hydraulic JonRie winches,” says Mr Durar.
On the bow of each tug there will be a JonRie Series 210 heavy duty hawser winch complete with a standard render block. Mr Durar says these winches will have the capacity to spool 183 m of 18 cm hawser, a line pull of 9,070 kg, a line speed of 53 m/min and a brake capacity of 136,077 kg.
On the stern of these YT-808 tugs will be a Series 421 heavy duty capstan with a 45,360 kg of bollard capacity. The capstan will have a line pull of almost 70,000 kg and a line speed of 9.1 m/min.
Their engineroom drives will have a soft start and load sense system, plus controls and an electronic starter.
“A trend in the industry in deck equipment is to return to hydraulic systems for reliability,” says Mr Durar. JonRie also won the contract to supply deck machinery for the US Navy YT-815 class tugs.
“Again, these will be all-hydraulic winch packages with a Series 220 double-drum winch on the bow for submarine docking and a series 421 aft capstan,” says Mr Durar.
To complete the set, the US Navy’s new T-ATS-6 Navajo-class salvage tugs will have a full hydraulic package. “Again, this is due to the reliability issue facing the US Navy today,” says Mr Durar.
The US Navy’s LPD-17 class vessels all have electric windlasses, “but the next in the series will be a hydraulic drive again to return to legacy equipment that works”, he adds.
After launching the first YT-808 tug, Dakota Creek Industries expects acceptance trials will be conducted in July and delivery to the US Navy should be in August. It anticipates delivery of the other five tugs in the series will be from Q4 2020 to Q1 2022.
Gulf Island Shipyards is building towing, salvage and rescue T-ATSX-class vessels for the US Navy’s Naval Sea Systems Command. For these vessels, it selected MacGregor to provide deck machinery. These packages include a main towing and traction winch, offshore crane, Triplex shark jaws, towing and pop-up pins and a stern roller.
Digital twin design
MacGregor uses digital twins and 3D simulations of deck equipment to monitor their condition and performance in their operational environment. MacGregor vice president for digital and business transformation Dennis Mol says digital twins can be adapted for client requirements and different applications.
“A digital twin provides cost efficient and low-risk learning compared with the physical world,” he says. “It is tailored to different value streams of each customer process, by understanding its specific operation.”
Digital twins can be used during system design, engineering, building and testing, to simulate equipment operations, servicing and maintenance and provide a tool for training crew.
“In design verification, it is about saving time by rapid prototyping and faster requirements definition,” says Mr Mol. “It is about clear scoping in terms of functional features and benefits.”
Using digital twins to lower pre-calculated risk margins will “avoid cost over-runs and future failures” or excessive costs.
“It is about avoiding incidents by teaching correct equipment use,” he explains. “To train crew on board, thus saving travel to training centres and avoiding wear and tear on equipment.”
Digital twins can be used to provide maintenance advice to crew to fix operational issues. “We can avoid service visits and improve logistics,” says Mr Mol.
MacGregor develops digital twins in collaboration with its vessel-owner customers to produce value for all stakeholders. “Digital twins can replicate and predict future operations or help provide advice and actionable insights,” he continues. “With early-adopters we are striving and exploring value creation in their processes.”
Vessel owners gain value from the improved design and engineering of MacGregor cranes and winches, also benefiting from improved maintenance, higher safety and less downtime.
Turkish tug deliveries
DMT and Data Hidrolik supply deck machinery to tugs built in Turkey. DMT says it has supplied Type TW-E 250KN electric double drum hawser winches to tugs built by Sanmar Shipyards, including Boğaçay-class tugs. These winches generate a pull of 250 kN at up to 9 m/min on low speed and 80 kN at 28 m/min on high speed.
For Boğaçay-class tugs, Data Hidrolik supplies 5-tonne aft capstans and tow hooks. It offers five different models of towing hooks, starting from 15 tonnes up to 100 tonnes safe working load.
Data Hidrolik manufactures electric or hydraulic motor-driven windlasses and capstans in horizontal and vertical versions. Its capstans are rated up to 11 tonnes of pull. They are designed with gears and motors below the deck for an uncluttered deck. Its windlass range is from 8 mm up to 42 mm stud-link chain and up to 12 tonnes pull.
Palfinger supplies 21 Pacific patrol vessels
Palfinger is working through a major order to deliver foldable knuckle boom cranes for a series of patrol and emergency response vessels being built in Australia. Shipyard Austal is building these vessels for the Commonwealth’s Pacific Maritime Security Programme in the South Pacific.
These 21 Guardian-class patrol boats will serve 13 Pacific island nations by 2023. Each will have one Palfinger PK15500M foldable knuckle boom crane. Already, nine of these have been supplied for these 39.5-m steel-hulled vessels. These cranes will be used for multiple lifting applications.
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