Pacific Maritime Magazine - Marine Business for the Operations Sector

Bay Delta Builds "Multi-Purpose" ASD Tug for Foss


September 1, 2017

Vessel Chartering LLC of San Francisco has introduced the multi-purpose 110-foot tractor Caden Foss to offer both ship-handling and long-haul towing capabilities in one hull. Photo courtesy of Baydelta Maritime.

The Pacific Northwest has been at the forefront of North American tug design since the 1980's, and has brought many innovations to both ship-handling and long-haul tugs. Over the years, a handful of boats have attempted to combine both these functions in one hull, but the goal of a truly "multi-purpose tug" has remained elusive. Vessel Chartering LLC of San Francisco, a division of Baydelta Maritime, is the latest operator to try their hand at this challenge with a 110-foot by 40-foot tractor design. It was jointly developed by Baydelta and Jensen Maritime, the Seattle naval architects who have produced many successful tug designs in this size range.

Construction began early in 2016 at JT Marine in Vancouver, Washington. The vessel was launched in May 2017 in Foss colors with the name Caden Foss and entered service in August for an initial three-year charter. Baydelta operations manager/port engineer Peter Zwart was responsible for this project, which utilized all the experience gained from the company's previous new-build program from 2006-2014 that produced a fleet of six versatile 100-foot tractor tugs. These were built by Nichols Brothers to a class design from Jensen with a 90-ton bollard pull. The Delta Audrey, Delta Billie and Delta Lindsey were retained for the company's own use, while three more were long-term chartered to other SF Bay operators Foss and Crowley.

Baydelta was formed in 1993 by three San Francisco Bar Pilots who brought all their experience to bear in their choice of tugs and gear. The company provides ship assist, petroleum escort and general towing services throughout the San Francisco Bay area as well as undertaking offshore assignments.

Baydelta completes 500 to 600 escorts annually as part of a system that is heavily regulated by California's Office of Oil Spill Prevention and Response (OSPR). The ships pass under three bridges, with strong currents and winds, narrow channels and commercial and recreational traffic.

Environmental Considerations

Zwart explained that company co-owner Captain Ron Charlesworth recognized in 2014 that there was an opportunity to build and charter a new boat on the Bay, particularly a court ruling on Chevron's Richmond refinery modernization project, which required the company to cap greenhouse emissions at current levels and provide electrical supply/cold ironing to tankers at the dockside. The choice of engine was also dictated by EPA rules, which now require Tier 4 emission controls, and the tug was also designed without any ballast tanks, eliminating the need for ballast-water treatment.

The decision was made to start with a clean sheet and build on the proven Delta 100's – with some ideas from Jensen's popular 120-foot Titan ocean-going class. Finally, Zwart was able to return to Jensen with a full-fledged concept for the multi-purpose boat. His checklist now included a full-length keel with an 18-foot draft for escort work, an aft deck laid out for barge towing with wire or on the hip with synthetics, and comfortable accommodations for long haul towing. The 100's can carry 70,840 gallons of fuel, but the new design would need a fuel capacity of more than 120,000 gallons to give it real long-distance towing ability.

That 70 percent increase definitely required greater length to support the extra weight, Jensen pointed out, and 110 feet was the absolute minimum. The foredeck was raised by four feet to allow full crew accommodations in the foc'sle. These were just the first of many compromises that were made to achieve the multi-purpose ability. An additional requirement was the ability to turn 11,000-TEU container ships in the confined (1,400-foot) Port of Oakland turning basin, and also be capable of moving barges around the bay.

According to Zwart, the key to a successful charter is to anticipate where the industry is heading and find new design features or technology that are likely to add value, safety or efficiency in the future, and incorporate these in a complete package to present to a potential charterer.

Selective Catalytic Reduction

A pair of the newest Caterpillar products, the 3516e Tier 4 diesels came packaged with Selective Catalyst Reaction (SCR) chambers. These neutralize the harmful NOx in the exhaust by scrubbing it with a urea solution carried in a 4,600-gallon stainless steel tank – enough to treat the maximum fuel capacity of 123,000 gallons at the standard 5 percent rate. The power is increased slightly to 3,385 HP and the engines and entire space is painted white – following a Baydelta tradition. The crew will transfer some of the 123,000 gallons of fuel between tanks in order to maintain proper trim.

On Jensen's first Tier 4 build, the 120-foot Earl W Redd, the 6.5-foot by 5.25-foot x 3.3-foot SCR container is placed on the main deck in the fidley, but on the 110, this free space was not available. Instead, the SCR unit has been turned on its side and attached to the overhead aft of the engine and above the Centa carbon fiber one-bearing shaft. It is wrapped in a standard insulation blanket, and is equipped with sensors to measure the percentage of the exhaust gases before and after treatment.

With the extra freeboard of this hull, the installation is remarkably clean. However, the exhaust flow builds up heat in the chamber, which has been found to raise the temperature in the engine room. This has been a real challenge that was not recognized initially, said Johan Sperling, a Jensen VP. He had to go back to the drawing board to increase the size of the ventilation ducts. Sperling says the vessel's length is sufficient to give it the towing performance and range of the Titan class, while still providing the maneuverability and feel of the Delta class tugs.

Two Cat 71-150 kW gensets are located forward and to port of the mains next. Like the Delta class, the 110-foot boat has firefighting ability with a Stang 1,400-GPM monitor driven by a 100-HP electric motor, giving it a FiFi Class 0 rating. The main switchboard is to starboard, and the third gen-set required by the OSPR for back-up during tanker escorts is a Cat 65 kW installed aft in an insulated cover to reduce noise when not under way.

There is also a centerline compartment aft of the engine room that is dedicated to housing the switchboards and control panels for all accessories, including both winches, the twin Rolls Royce 255/3800 FP azimuthing drives, pumps and hotel loads. On one wall, Woodward's easYgen-3000 Series paralleling genset controllers combine generator control and protection with advanced paralleling function through the LogicsManager programmable logic function that can easily integrate with SCADA or PLC-based control systems.

On the bow is an electric Markey Model DEPCF-52-75HP Class II Hawser Winch. It has a drum capacity for 450 feet of 3-inch diameter soft-line and has a rated performance of 30,800 lbs at 378 feet per minute, giving a 95 short-ton bollard pull that will be capable of handling container ships up to 18,000 TEU.

Included in the package is the Markey Render/Recover feature that allows for hands free operation at up to full rated line-speeds and line-tension.

For barge towing, the aft winch is a 100 HP electric, double-drum tow winch that is a brand new product from Rapp. It can pull more than 75 tons on the first layer, and wind 2,500 feet of 2.5-inch wire on the port side and wrap a shot of chain on top of it via an offset level-wind. The Rapp pin box holds four pins with hold-down hooks. To fulfill the dual-purpose demand, the starboard winch drum carries a synthetic hawser used to snug a barge up on the hip via a small 50-ton staple on the aft deck. There is a back-up motor if the primary driver fails, and all controls are pneumatic. This design is a significant addition to Rapp's range of winches, says Johann Sigurjonsson, president of Rapp USA.

The Caden Foss is well-protected on the bow by an unusual double row of Shibata rubber cylinders above a laminated wrap-around Schuyler pad, plus eleven vertical strips of D-rubber at the waterline. Two layers of D-rubber are wrapped around the stern, with tires amidships. This is to accommodate ships and barges of any size and draft.

The Caden's Selective Catalyst Reaction (SCR) chamber has been turned on its side and attached to the overhead aft of the engine and wrapped in a standard insulation blanket. Photo by Peter Marsh.

The spacious wheelhouse provides all-around visibility and also meets the multi-purpose description: while the pilot has a conventional ASD helm station, the aft end of the house is devoted to the boat's offshore function with matte black overhead paneling, a chart table, with an aft-facing set of duplicate helm controls plus the towing winch control panel. This uses Rapp's patented PTS Pentagon Control System providing the operator full control and data tracking of winch use for maximum safety at sea. Navigation electronics are by Furuno and the ergonomic helm chair is a Bostrom Sea Post.

The deckhouse is large enough to accommodate a spacious galley, mess and lounge, and officers' quarters. The three crew cabins in the forecastle under the raised foredeck are also very well furnished. The maximum capacity in the five rooms is ten, but Zwart expects the most crew will be six to eight when offshore. Fresh water capacity is 4,300 gallons, with a water maker available for the long hauls.

Zwart says Foss is pretty happy with the tug, which demonstrated a bollard pull of better than 91 short tons over the bow and 92.1 over the stern. "We've done our best to give the Caden the ability to handle practically every type of tug work on the west coast that we can foresee," Zwart told Pacific Maritime after the tug arrived on San Francisco Bay. "We think the industry will be watching it with interest."


Powered by ROAR Online Publication Software from Lions Light Corporation
© Copyright 2020

Rendered 10/30/2020 11:01