Custom Cable System Makes For Smooth Sailing for Crowley's eWolf

 

The maritime industry — like many industries — is seeing more electrification to reduce carbon emissions, enhance environmental sustainability and safeguard marine ecosystems. One recent example is the launch of the eWolf, an all-electric tugboat that eliminates emissions and is poised to significantly curb air and water pollutants.

One pivotal aspect of maritime electrification is the shoreside power infrastructure, which must offer quick connection and disconnection to the charging system to charge the vessel’s batteries. For eWolf, this meant designing a special plug delivery system that could meet several challenging technical requirements, all while providing a reliable and uninterrupted power supply.

Fortunately, igus® was up to the challenge. To support eWolf, the company designed a custom version of its e-dispenser® shore power system, which offers smooth cable retraction and extension for fast, efficient charging. In addition to being an important part of the tugboat's electric operations, the e-dispenser represents a milestone in the electrification of maritime vessels.

About the eWolf Tugboat

The eWolf electric tugboat is the first fully electric tugboat to be built and operated in the U.S. Designed to operate with zero emissions, it provides a sustainable alternative to traditional diesel-powered tugboats. Designed by Crowley Engineering Services, the 82-foot-long tugboat supports ship arrivals and departures at the Port of San Diego, California. It’s equipped with an integrated electric propulsion system, which includes a 6.2 megawatt-hour energy storage system (ESS) that enables the vessel to operate for a full day on a single charge.

Part of the Port of San Diego’s Maritime Clean Air Strategy, the eWolf’s zero-emissions design is part of broader sustainability efforts and is expected to reduce emissions equivalent to over 350,000 gallons of motor vehicle gas during its first ten years of operation.

The Need For an Innovative Cable Management System

igus® played a crucial role in eWolf’s development by designing a custom cable management system based on its e-dispenser® shore-power system. Essential for delivering power from the shore to the tugboat, the e-dispenser delivers a plug to the tugboat to charge its batteries.

The plug delivery system had to meet several technical requirements, such as handling the large cables and connector needed to meet the eWolf’s high power transfer requirements. It also needed to accommodate the tidal ranges at the Port of San Diego, ensuring there was always enough extra cable to cycle through the range without pulling cables attached to the vessel without impeding other operations on the pier. Part of meeting these requirements involved the use of special cables with very tight bend radii to prevent cable loops from protruding into work areas.

Perhaps most importantly, the cable system had to be fast. Tugboats have limited charging time, and operators need to connect and disconnect power as efficiently as possible. When these vessels dock, cable systems must deliver power immediately. Once the charging is done, the system needs to power down and disconnect rapidly so the tugboat can promptly return to service. This quick-connect capability maximizes operational time on the water and ensures vessels receive necessary power during their brief shore visits.

Customization and R&D Efforts

For igus®, developing the e-dispenser for the eWolf was a unique R&D effort, requiring input from various stakeholders, such as the battery system manufacturer, the vessel design team, charging system team and team from the port. igus® also worked closely with safety experts, who had to qualify the system for marine environments and ensure the system could withstand seismic events, wind speeds and storm conditions.

In this application, the e-dispenser included several igus® core products, many of which had to be modified because of the high loads and tensile stresses involved. For example, the system included triflex® e-chain® cable carriers, which the igus® team strengthened with the addition of a metal pin to the spherical ball connection. For cable management, the team incorporated standard chainflex® products, whose torsion capabilities and small bend radii are ideal for continuous flexing.

Durable yet flexible, igus® chainflex® cables and e-chain® cable carriers can withstand harsh marine conditions, including exposure to saltwater and extreme temperatures. They are also tested for over 10 million cycles, ensuring long-term reliability and efficiency.

Standout Cable System Features

The result of these R&D efforts was a custom plug delivery system that eliminated the need for slip rings, ensuring a reliable and uninterrupted power supply for eWolf. Thanks to its smooth cable retraction and extension, it created a fast yet safe plugging procedure. In fact, disconnecting the plug from the eWolf takes only a few minutes.

One of the e-dispenser’s standout features was its quick onsite installation. igus® delivered the entire system pre-assembled in a single open-top container, with the boom folded down for transport. Once on site, crews used just one crane operation to lift the complete unit from the container and position it on its foundation. The only other assembly processes were selecting the location to mount the operator stations and terminating the shore power cables.

The e-dispenser was also designed to handle different cable configurations and connector styles with the same delivery system. AC, DC or low- and medium-voltage can all be implemented within the same size, shape and function of the e-dispenser without custom multiconductor cables that drive cost.

The eWolf tugboat is a groundbreaking innovation in maritime applications, demonstrating the potential for zero-emissions operations in a traditionally diesel-dependent industry. igus®'s contribution to the eWolf project, through the development of a custom plug delivery cable system, was crucial in enabling the tugboat's electric operations.

This article is sponsored by Igus. For more information, please visit www.igus.com.