Computerized controls automate many vessel operations
By Larry Pearson
It was inevitable. For several years now crew/supply boats have been following, almost in lock step their "big brothers," the supply boats, with technical and other innovations. Drop down bow thrusters, DP-1 systems, better crew accommodations and advanced radar systems are just a few of the features first introduced on supply boats and now available on crew/supply boats. The next step in this evolution is the introduction of automated monitoring, control and alarm systems on crew/supply boats. Trico Marine, Houma, La., is now operating three 155-ft. by 28-ft. crew/supply vessels that feature what is believed to be the first ever state-of-the-art automation system on this vessel type.
Gulf Craft, Patterson, La., built the three identical vessels. The last of the trio, Tennessee River was delivered in March 2003. The Holston River and the French Broad River were delivered in 2002. The alarm and monitoring system covers 96 points on the vessel, but the system uses a touch screen monitor rather than banks of "idiot lights" to report on the condition of the points being monitored.
The systems covers main engine operation, generator operations, the bilges, the bow thruster and tank levels. A touch of the screen will instantly show the status of all points being monitored with those in an alarm status being shown in red. The Trico vessels have nine tanks below deck, four holding fuel and five holding water. The level of each tank is displayed on a single screen with vertical bars. Besides each bar is shown the condition of each tank in percentage full. Any tank above 94 percent full is considering to be in an overfill condition and that tank is show in red on the display. Once a tank falls below 8 percent full that condition is also reported in red. A Remote Monitoring/Valve Control panel contains an open/close switch for each tank as well as start and stop push buttons for the fuel oil pump and the cargo water pump. The tank switches operate pneumatically, a very simple and straightforward system, decidedly low tech. But how the valves get the signal and the amount of wiring to do the job is one of the exciting innovations on the vessel. As shown in Figure One, the conventional wiring method calls for nine five-wire cables to be installed, one cable for every valve. (Figure One only shows five valves, but these vessels have nine tanks, so nine valves are needed.)
On these vessels, Actuator Sensor Interface (AS-I, pronounced 'Ozzie') wiring is used. As shown in Figure Two, a two-wire cable is used, connected in series with all nine valves. One two-wire cable instead of nine five-wire cables represents a huge savings in both cable cost and the labor cost of installing this wiring. "The AS-I wiring method uses addressable signals," said Jack Rowley
, general manager of Engine Monitor, Inc. (EMI) supplier of the system. "That is, each of the nine valves has a distinct electronic "address" and respond only when that specific address is sent over the two-wire system," Rowley continued.
The Program Logic Controllers (small preprogrammed mini-computers) are one of the keys in operating the AS-I) system.
The vessel is powered by five Cummins KTA-38M2 diesels rated at 1,350 hp each at 1,800 rpm. That is a total of 6,750 hp for propulsion that provides a light ship speed of 28 knots and a fully loaded speed of 23 knots. The engines work into Twin Disc reduction/ reversing gears that are set for a 2.46:1 ratio. The shafts spin four blade Nibral propellers. To enhance maneuverability, the vessel features a Wesmar 200 hp tunnel bow thruster that is powered by a Cummins 6CTA8.3 engine. The other end of this engine drives a hydraulic pump. Other machinery on the vessel includes a pair of Cummins 6BT series engines driving 75 kW generators. Cummins Mid South, Morgan City, La., supplied all engines on the vessels.
In its role as a crew boat, the vessel can accommodate 78 passengers in reclining bucket seats. The air-conditioned main deck passenger compartment features a 32-in. television for passenger entertainment. Aft on the port side of this compartment are two heads. Crew accommodations are in the hull with five staterooms. Two of the staterooms are made up with a single berth with clothes locker and a television and a VCR. The other three staterooms have two berths and one clothes locker per cabin. The crew head is arranged with a lavatory, head and shower
Also in the crew quarters is a galley with an eight-person mess/lounge with an entertainment "wall" consisting of a television, VCR and stereo. A laundry room with crew clothes washer and dryer and an additional chest freezer is in an adjacent compartment. These three boats are prime examples of the forward thinking of vessel operators such as Trico Marine in devoting an increased amount of space to crew accommodations, off-watch entertainment and comfort. A well-rested and contented crew is obviously safer and more productive.
As a carrier of drilling liquids in the hull and bulk cargo on deck, these vessels have plenty of capacity. Cargo on the 88-ft. by 22-ft. main deck aft of the superstructure can reach 250 long tons. Liquid capacities include 31,500 gallons of drill or potable water and 24,000 gallons of fuel oil. Transfer rates are 300 gallons per minute at 220 ft. for both fuel oil and water.
The pilothouse includes well equipped forward and aft facing stations. Navcom electronics include two Furuno radars, three ICOM VHF radios, a Furuno single side band unit, a Garmin GPS, a Furuno depth recorder, a JVC Navtex receiver and a Raymarine loud hailer. The engine controls are by EMI and the steering is electronic over hydraulic, also by EMI. EMI supplied five engine throttles for both forward and aft stations. Even though the vessel has five engines and five propellers, it has two rudders placed behind the port and starboard engines. "The rudders have more "bite" placed over the far outboard engines," Rowley said. The three vessels have a Coast Guard Certificate of Inspection as Subchapter T vessels. They are also ABS classed ABS+AI HSC Crewboat + AMS and have an ABS Load line Certificate. The vessels have a DNV tonnage certificate of 95 Gross Registered Tons (GRT).