Baydelta's Hybrid Tug: Batteries Not Included
Vessel Profile: Delta Teresa
July 1, 2019
The Delta Teresa, the first hybrid diesel-electric tug designed by Jensen Maritime Consultants, was successfully delivered to Baydelta Maritime in San Francisco by Nichols Brothers Boat Builders on April 19. It arrived ten years after the world's first hybrid tug, Carolyn Dorothy, was launched by Foss into the Columbia River and began service in Long Beach, so has attracted national attention as the new generation in hybrid technology for the tug sector.
Delta Teresa joins the Bay delta fleet of six conventional 100' x 40' Valor-class tugs all designed by Jensen and built by Nichols. They are responsible for assisting many of the large container ships and tankers that visit San Francisco Bay.
This large body of water is covered by strict state emission/environmental rules for all marine traffic, which has resulted in a steady upgrade in the engine technology used in the Bay Area's many ferries and tour boats that lead the nation in application of clean-propulsion technologies. However, American tug operators as a whole have been reluctant to test hybrid concepts in the last decade, and Foss re-assigned its first hybrid from Southern California to the Columbia River in 2017.
The next region to test hybrid tugs is the busiest port in Europe, Rotterdam, which also has strict air quality rules. In 2012, the E-KOTUG RT Adriaan was converted into a hybrid with a battery bank and control system from Xeropoint, the Canadian specialist that had supplied the software for the Foss tug. KOTUG followed this success with two newbuilds, using KOTUG's patented Rotor propulsion system of two ASD's forward and one ASD aft. Power came from three Caterpillar 3512 C main engines supplemented by large (117-kW) battery banks.
This system of main engine plus battery bank is the standard approach for hybrid vessels of all types, especially ferries, since it allows them to use silent battery power while docking and idling, and permits hybrid tugs to shut down the mains when on stand-by or in slow transit. However, despite the huge amount of research and development by international engine manufacturers and the success of hybrid cars, this remains a complex and expensive strategy for a one-off tug.
To meet all of the San Francisco region's future environmental rules, Baydelta chose a simpler hybrid alternative developed by Rolls Royce Commercial Marine. This follows the traditional diesel-electric model by connecting the gen-sets directly into the ASDs via a "Power Take-In" (PTI) that eliminates the cost and weight of a battery bank, but still provides operational flexibility. It consists of the company's own electric motors, azimuth thrusters, control system, main switchboard etc. with the vessel owner's choice of main propulsion engines and gen-sets.
(Note: With the sale of the Rolls Royce marine division to Norway's Kongsberg Maritime on April 1, this system is now called the "Kongsberg PTI Hybrid Propulsion System.")
The Delta Teresa was the first-ever hybrid tug application for Baydelta, Jensen and Nichols. Like the latest Valor-class tugs, the Delta Teresa is powered by two Caterpillar C3516 C Tier 3 diesel engines each rated at 2,650 hp/995 kW at 1,650 rpm for a total of 5300 hp. The conventional power drivetrain uses Centa carbon fiber shafts to turn the two ASD's (now re-named Kongsberg 255FP's) and produces a bollard pull of 70 short tons. The Kongsberg control system allows the vessel to operate in either a conventional diesel-mechanical mode, diesel-electric from the four gen-sets, or boost mode configuration combining shaft power from the mains and electric power from the gen sets.
Supplementary electrical power is provided by three 300-Kw CAT C9.3 generators and one 150 kW CAT C7.1 – all 480-Volt 3-phase at 1,800 rpm – that power a pair of Kongsberg 454-kw electric motors mounted horizontally on the ASDs. They add approximately 1,300 hp to the mains, resulting in 21.5 short tons of additional bollard pull in combined mode for maximum thrust of more than 90 short tons. Free running speed under electric power alone is better than 9 knots.
The bow hawser winch is a Rapp HAW-75E with electric drive that can pull 16 tons and store more than 850 feet of 8-inch circumference hawser rope. The electric tow winch on the aft deck is a Rapp AHTW-50E single drum, which is set up for softline towing and offshore rescue work and will hold approximately 1,200 feet of 2-inch synthetic rope. Both winches are equipped with level winds and multi-disc clutches that will disengage the drum from the drive line for either routine operations or in the event of an emergency.
The main control stations for both winches are situated in the wheel house and employ the company's advanced Pentagon Tug PLC Control System that provides more efficient and safer operations for towing vessels. Secondary controls are located on the winch. For a full description see the Deck Gear survey in this issue. Note that Rapp is now owned by McGregor, part of Cargotec.
The large pilot house has all-round visibility and is equipped with a full range of Furuno electronics.
The deckhouse has space for a large comfortable mess, galley and lounge area. Accommodations include staterooms for the captain and engineer and three staterooms for crew. The seven crew are served by two heads, a shower, laundry and a lounge, which includes wi-fi and cell phone boosters and digitally controlled air to liquid HVAC systems for each space.
Commenting on their operational performance, Baydelta's Captain Mike Peery said, "The Teresa is equal to our other Valor-class vessels in power, but exceeds the others in versatility by increased propulsion options and infinitely variable thrust, provided by the Kongsberg PTI system, for sensitive operations demanding less prop wash."
Owner Baydelta Maritime is a family-owned tugboat operating in San Francisco Bay since 1982. The company has around 30 customers, including major oil companies, and served the five oil refineries in the San Francisco Bay. The Delta Teresa cost more than $10 million, according to Ralph Silverman, commercial director at Baydelta Maritime, and the hybrid system probably added about 5 percent to the total cost, he estimated.
"This is our seventh Delta Class tractor tug for Baydelta Maritime," said Matt Nichols, executive vice president of Nichols Brothers Boat Builders. This is the most developed and cleanest hybrid we've ever done. Everything keeps improving all the time – process, equipment, electric panels."
Peter Zwart was the VP of Operations at Baydelta Maritime who supervised the design and construction of all seven Valor tugs and the 110-foot multi-purpose Tier 4 design Caden Foss. Sadly, the company reported his death at age 68 on January 11 in Sausalito. He was born in the North Sea port of Ijmuiden in the Netherlands. In his 20s, he sailed around the world as an engineer until he was in his 30s when he settled on a houseboat in Sausalito and joined Baydelta. As port engineer and operations manager he was responsible for the company's new-build program from 2006-2014. The Delta Teresa was named after his wife, Maria Teresa Aguirre Guarneros.
Bryan Nichols, director of business development at Jensen Maritime, said: "We have a long-standing partnership with Baydelta and are proud to once again be chosen for this historic build. It demonstrates our commitment to innovative, environmentally friendly design while continuing to deliver powerful, high-quality performance."
Kongsberg has already installed hybrid systems in almost 40 vessels around the world that include DPV's (dynamic-positioning vessels), ferries and a 1914 Danish sailing ship that can produce its power when sailing at speeds of more than 8 knots with the propeller connected to a shaft generator.