Professional Mariner - Puget Sound ferry uses its design to good effect in difficult waters
Professional Mariner, Alan Haig-Brown, April 4, 2011
The Port of Keystone in Washington state's Puget Sound sits like a reversed barb on a fishing hook with the long stretch of Admiralty Bay extending southward like the shaft of the hook. The bay collects and focuses the north-flowing ebb currents from the bay and whips them around the stone jetty that forms the harbor. On a strong ebb, the currents can reach 7 or 8 knots off the jetty.
Mark Haupt, the senior Washington State Ferries captain on the route that runs from Keystone on Whidbey Island to Port Townsend on the northeast corner the Olympic Peninsula, explained that the port is more like a keyhole than a keystone. The run from Keystone to Port Townsend is only 4.9 miles, but tidal currents that can exceed 4 knots across the ferry's track can require a modified route of more than twice that distance.
The route saw the inaugural run of a new ferry, Chetzemoka, in mid-November 2010. By Dec. 7 the crews had had enough time on the new vessel to confidently declare it to be up to handling the difficult run even on those winter days when strong winds built sharp-crested waves when pushing against the strong tides that attempt to fill and empty the whole of the expanse of Puget Sound in five or six hours.
The route is located just around the corner from the 80-mile reach of the Strait of Juan de Fuca, so large Pacific swells can add to the confusion of seas built by winds from either the northern or southern reaches.
We can get 20-foot seas in here explained Capt. Haupt.
He has not yet had to put the new ferry through the most extreme maneuvers that heavy weather can dictate. One such is to leave the harbor at Keystone and turn southwest to quarter into the seas built by winds from southern Puget Sound. Then, having traversed half the width of the channel but remaining well south of Port Townsend, the crew will reverse the double-ended ferry and proceed on a northwesterly course to their destination.
Such a maneuver also requires handing off controls from the wheelhouse on one end of the ship to the wheelhouse at the other end. On the new ferries, the wheelhouses might more properly be called bridges, as they extend the full width of the ship and provide good visibility on either side. For passage through the narrow entrance of Keystone, Haupt has lookouts on both of these bridge wings.
The design of Chetzemoka was adapted from the East Coast ferry Island Homeoperated by the Woods Hole, Martha's Vineyard and Nantucket Steamship Authority. To reduce costs, the two wing controls were deleted in the redesign, but the fore and aft visibility afforded is still much appreciated. In another innovation from Washington State Ferries, no photos are allowed on the bridge or in the vessel's engine room. This measure, along with a cage-like structure over the bridge deck access, is apparently to foil pirates or terrorists who might endeavor to take over the vessel.
On a crossing from Port Townsend to Keystone, veteran quartermaster Bill Britt navigated across the channel. As the ferry neared the entrance to the harbor, Capt. Haupt took the helm and Britt moved to the port bridge wing, while another crewmember observed from the starboard wing.
A gravel beach to port and a kelp patch to starboard encroached on the already narrow 360-foot harbor entrance. With a draft of 11.5 feet and three decks of sail-effect, the ferry can pose a challenge to the crew trying to fit the ferry's 64-foot beam between the shallows on either side of the entrance. On this relatively calm December day, it was a smooth entrance; but it is easy to see how, with 30 or 50 knots of wind and strong tidal currents swirling around the rock jetty, this would be no easy task.
In extensive sea trials, Washington State Ferry skippers like Haupt worked with Karl Senner, the Reintjes gear supplier, Prime Mover Controls and EMD to find just the right ramp speed to avoid propeller cavitation and the resulting vibration. Once the correct rate for increasing speed was determined, it was programmed into the controls software so that the boat is now a very smooth operation.
This is a very situational run,â€ Haupt explained. We dont enter Keystone for one hour on either side of the peak of a 3.5- to 3.7-knot ebb or for an hour and a half on either side of a 3.8 or greater maximum ebb.
To avoid shutting down operations, although that can happen, Haupt sits down with the terminal supervisor to map out replacement trips for cancellations due to the tidal current limits on entering Keystone. These three-month projections are then published so that people can plan their ferry rides to avoid those times when the ferry would be unable to enter Keystone.
The fore-and-aft propulsion allows for a controlled entry to the ferry slip, while Chetzemoka's Becker-type articulated rudders will allow for precise alignment.
The rudders are particularly impressive to Haupt and his crew. In a demonstration midway between the two ports, the rudder was set at 25° and this allowed the 273-foot vessel to make a 360° turn and end up just inside its starting point. Traveling at its transit speed of 13 knots at the beginning of the turn, the vessel had slowed to 4.5 knots at the completion of the circle, which took only about two minutes.
Haupt explained that the turn was made with very little list because of its shallow draft and rolling chocks that extend out from the upper chine and extend over about 40 percent of the vessel's length.
Loading and draft are always a concern on car ferries. Haupt likes the Weir-Jones Group Automatic Draught Indicator mounted on the bridge that allows him to see at a glance the port and starboard draft and freeboard at each end and midship.
Much of the automated engine room can be controlled from the bridge. But there is plenty to do for Staff Chief Engineer Eric Liu with oilers Scott Ohman and Beth Bland. The team is kept busy maintaining the engines and the complex of generators, boilers, sewage, and water-fog-fire-suppression services that a large passenger vessel requires.
With capacity for 750 passengers and 64 cars or a smaller number of heavy trucks, the ship's services require constant monitoring, which is done in a control room with excellent visibility of the two 3,000-hp EMD 12-710 main engines. A full slate of software allows monitoring of all systems with graphic displays on monitors. When the ship is in one of the slips, the display shows the propeller on one end to be green to indicate that it is pushing the boat into the slip, while the other end is clear indicating that it is not in gear. When the ferry is traveling, the forward prop is allowed to freewheel, while the rudder is locked in a neutral fore and aft position.
Liu's oilers follow the regular circuits of the engine room required by Washington State Ferries. Recalling the instruction he received when he was starting out, he encourages them to take a hands-on approach.
Touch the engine; see which lines are hot and which are cold. If you see oil where it shouldn't be, then check it out. It is too easy to become detached with a keyboard and a computer screen, explained Liu, adding, When things are going wrong, it is not the time to be figuring things out.
The hull has seven watertight compartments, with water and sewage in the two end compartments, workshop and stores in the next compartments. The two compartments adjacent to the centrally located engine room contain the big Reintjes WAF 3445K reduction gears that are separated from the main engines by a shaft that passes through a watertight bulkhead. A tail shaft then carries the 3:1 reduced rpm to the propeller. The single centrally-located engine room has the two EMDs mounted nose to nose with their cooling systems mounted off to one side and a pair of Detroit-powered 300-kW generators on the opposite side.
The engine room crew is one of four crews working 12-hour watches with seven days on and seven off. In this way, the maintenance is done by the crew on the night watch. With the existing shift rotation, everyone gets sailing and maintenance time rather than having separate sailing and maintenance crews. Crews switch between the day and night watches with each rotation.
The deck crew comprises captain, mate, three able seamen and two ordinary seamen.
Ordinary Seaman Allan Stewart has come in from the deep-sea ships and lives a quiet life on the Olympic Peninsula a short drive from the ferry's home terminal of Port Townsend. He acknowledges that this run, in spite of the heavy weather, is a far cry from some of his early voyages in the 1970s with long periods away from home, such as the time his crew took the ship Steel Director to be scrapped in China.
They flew us home and I still have the ship's engine room clock, he recalled.
Although most crew can get home when off watch, a number of crew and officer bunk-rooms are provided for those who wish to stay on board.
After only about three weeks in service, Chetzemoka was getting high marks from passengers and crew alike. Nos. 2 and 3 in the series of new ferries, Salish and Kennewick, will have controllable-pitch rather than fixed propellers. Other minor changes are being made to the design, which originated with the Elliott Bay Design Group.
One feature of the original East Coast ferry Island Home that might serve the Port Townsend-Keystone route would be the car deck doors that would reduce the effect of waves that can come over the bow and wash down the car deck, requiring that all passengers be off the car deck even in moderate seas. At the same time, the absence of the bow doors made it possible to cut the center section of the foredeck back to form what some call â€œpickle forkâ€ decks, which allow excellent view of the loading ramp from the wheelhouse.
Capt. Haupt rode Island Home as part of a team that Washington State Ferries sent to investigate the design in 2008. Although he believes that an in-house design allows a boat to be tailored to the specific needs of a region, he is well pleased with the performance of this adopted design.