SEACOR CHEETAH: Fastest workboat on the waterNov 13, 2008 12:00 AM
|Capt. Martin Songer lets go the lines as deckhand Terrence Etienne looks on. (Brian Gauvin)|
While unable to travel quite 70 mph, the new 170-foot crew/supply boat did reach speeds of 42 knots during sea trials in the Gulf of Mexico, making it by far the fastest workboat ever built and challenging the dominant role played by helicopters as a fast, safe way to transfer workers out to rigs and platforms (box, Page 14).
|A view over the cargo deck aft from the pilothouse. (Brian Gauvin)|
The key to the speed of any vehicle, whether on land or at sea, is to look under the hood, or in this case inside the two slim hulls on which this vessel is built.
Each contains a pair of MTU 16V 4000 engines developing 3,305 hp and working into a Twin Disc Nico gear that reduces engine revolutions at a ratio of 2.17:1. The engines power Hamilton HM811 waterjets. In each hull there is also a 290 kW genset powered by a Cummins QSM11 engine and a 360°, 200 hp azimuthing bow thruster by Thrustmaster.
Look at just the hulls and you could be looking at one of several almost identical vessels designed by Incat Crowther of New Zealand and built by Gulf Craft Inc. at its Patterson, La., shipyard. In the past three years, Gulf Craft has finished out three of these hulls as fast ferries built to carry up to 500 people at 40-plus knots.
|Cheetah’s four MTU 16V 4000 diesels power Hamilton waterjets via Twin Disc Nico reduction gears.|
The new vessel can seat 149 passengers, the maximum for a Subchapter T vessel. Gross tons are also under 100, another requirement for Subchapter T.
The ability to transport a relatively large number of passengers at 40-plus knots changes the equation of using crew boats or helicopters for crew transport. With Cheetah, owners can carry more than twice the number of crew (149 versus 60 to 70 for a typical crew boat) at a speed differential of about 15 knots over existing boats.
“It is all in the numbers,” said Jason Miller, marketing manager for Seacor Marine. “Imagine a route where there are weekly crew changes from a Port Fourchon, La., base to two platforms about 83 nautical miles offshore, with Seacor Cheetah delivering and picking up 51 passengers at one platform and delivering and boarding 32 return passengers at the second platform, 15 miles away. Occupied seat-mile cost is 30 to 40 percent lower for Seacor Cheetah than a large, modern helicopter. This single crew change will save 40 percent in costs over the air route — and when the ability to carry 150 tonnes of deck cargo is factored in, the advantages of Seacor Cheetah are even greater.”
|One of two remotely controlled fire monitors capable of pumping 5,300 gpm.|
At 42 knots, Seacor Cheetah consumes 644 gallons of diesel per hour at 2,000 rpm. In cruising mode, at 38 knots, fuel consumption is 474 gph at 1,800 rpm. Even at economy speed, running at 1,500 rpm, the vessel scoots along at 31 knots using 265 gph — and Seacor Cheetah’s economy speed is several knots faster than the top speed of the vast majority of crew/supply boats.
“This vessel is unique in many ways,” said McCall. “The superstructure has one more deck than a typical crew/supply boat. Between the passenger compartment and the pilothouse is a deck for the crew. With the slim twin hulls devoted to machinery and tanks, the crew were allotted a deck of their own.”
This deck has five staterooms for 10 crew, with a galley, laundry facilities and a mess for eight people. Galley equipment includes a pair of refrigerators and two freezers plus a 27-inch TV with VCR/DVD combo in the galley.
“This is the first time in my memory that crew accommodations have windows,” McCall said. “We anticipate operating Cheetah with about five crew, but the extra bunks will come in handy during some trips.”
With twin hulls and separate engine rooms, the vessel is one of very few crew/supply boats with a DP-2 rating. At a rig or platform, the Kongsberg SDP 21 dynamic positioning system takes over the navigation of the ship.
The DP-2 system includes a pair of windbirds, two gyrocompasses, two position reference systems, two Garmin 2106 GPSs and two motion sensors. “Most rigs in deep water are floaters, moving in a 100-foot circle,” said McCall. “The vessel has to be aware of these movements and be able to adjust for them. Such precise navigation takes a toll on the captain if he is holding position near a rig for several hours without DP.”
Smooth ride ahead
Ride control is by VT Maritime Dynam-ics Inc. of Lexington Park, Md. For vessels traveling at speed, the ride-control choice is typically between trim tabs and interceptors, and Incat Crowther chose interceptors. “Interceptors can be easily integrated with most system configurations, are lightweight and use less power to operate than trim tabs,” said Joe Kubinec, general manager of VT Maritime Dynamics. “Effects of wave action are dampened by the interceptor, so the ride is better and the passengers arrive at the rig or platform more refreshed.”
Seacor Cheetah can carry up to 150 tonnes of cargo on its 91 by 30-foot rear deck. The rear deck is also approved for carrying combustibles in approved tanks.
Special equipment includes a pair of remote-controlled fire monitors with a capacity of 5,300 gallons per minute. While rig fires are not common, Seacor felt these would be helpful since, with its speed, Seacor Cheetah may be first on the scene of a fire.
Seacor Cheetah carries 25,900 gallons of fuel oil, about 50 percent of which is transferable. To document offloads, a 2-inch fuel meter with a ticket printer monitors the flow and delivers a receipt. Discharge rate is 120 gpm at 288 feet. Other liquids on board include 3,600 gallons of potable water, sewage, bilge oil, gear oil and main engine lube oil. Deadweight tonnage is estimated at 182 long tons.
Safety systems abound on Seacor Cheetah. For firefighting on board there is a fixed CO2 system in all machinery spaces. A closed-circuit television system covers the rear main deck, engine room and thruster room. There are 10 deck lights totaling 6,500 watts plus two forward searchlights and one 12-inch searchlight aft with a remote control. Smoke and heat sensors are located throughout the ship.
The pilothouse contains two Furuno depth recorders and engine control and steering by Hamilton, the waterjet manufacturer.
Navigation equipment in addition to the DP-2 system includes two Furuno 2127 radars and a ComNav 2001 autopilot. Communications gear includes two Icom M504 radios, a Furuno FS1503 SSB, International marine Sound Powered internal telephone, a Raytheon 430 loud hailer, VSAT Internet e-mail, and a Furuno NX700 Navtex.
A watchful eye
The vessel monitoring system is by CSP Electronics of Maurice, La.; all alarms and monitors are on a single display, which uses visual indicators as well as voice-annunciated audible alarms. Electronic modules can monitor up to 30 points on the touch screen, and interfaces allow the vessel to send critical warnings to shore personnel.
Seacor Cheetah will use night vision technology to help its captains see in the dark. Its Night Navigator 5000 image-intensified night vision and day color camera system will allow it to move around rigs and platforms without tangling with unlit buoys or other devices that are not picked up on radar. The system is made by Current Corp. of British Columbia. The day camera features a 26X zoom with continuous 360° rotation and a joystick.
U.S. Coast Guard documentation is Subchapter T/L, and ABS has certified the vessel as +A1 HSC Crewboat, +AMS and DP-2.
Outside its routine duties, Seacor Cheetah may be pressed into service during hurricanes when deployed in the Gulf. It started its working life off the West African nation of Angola; its first customer was Sonangol, which manages the country’s oil and gas reserves.
Each year, millions of crew transfers happen between boats or helicopters and the thousands of rigs and platforms that dot the Gulf of Mexico. Whether transfer is by sea, or air, the objective is to move personnel safely, efficiently and cost-effectively. Many think that helicopter transfer is the safest, but the numbers don’t bear that out.
Reflex Marine Ltd., of Aberdeen, Scotland, has developed a personnel transfer device that should eliminate almost all of these accidents.
Called the Frog, it is a stainless steel tetrahedral-frame capsule surrounded by crush-resistant flotation material that keeps the capsule upright and above the waterline. It also has a spring-loaded suspension system on the bottom to protect against heavy landings.
The Frog was initially developed to accommodate three or six people. Working with Seacor, Reflex Marine has developed a high-capacity, nine-person capsule, the Frog-9, for Seacor Cheetah. The capsule has been designed so that a stretcher can be used to remove injured workers from a rig or platform, replacing two of the seats. The stretcher can be restrained inside the capsule, protecting the victim from impacts and potential falls. A medic can occupy a third seat to provide medical assistance during the transfer.
According to a spokesman for Reflex Marine, Seacor took two Frog-9s to Angola with Seacor Cheetah. Both Seacor and Reflex think the capsule will supply a unique option for crew transfers in the Gulf of Mexico as well and may decrease marine transfer incidents by 80 percent. “The introduction of this vessel, coupled with the implementation of the Frog capsules, marks our attempt to shift the philosophy of personnel transfer,” said Jason Miller, marketing manager for Seacor Marine.