A crew that is well-versed in situation awareness understands that success in the marine environment requires paying attention to a baseline of signs and signals that are always present around our operation. When something out of the ordinary shows up, our chronic unease kicks in and we mentally prepare for action.
A steering failure does not always give signs that a breakdown is about to happen. A weak circuit breaker, a broken feedback arm or a supply line leak can develop quickly without much warning.
Crew members who are well trained know how to react in an emergency. A steering failure requires quick thinking and a logical plan.
A seemingly routine voyage as the tow nears a bridge quickly becomes dramatic as the steering system fails to respond. The sticks are hard to port and nothing is happening. The tow is heading in the wrong direction and the bridge is coming up quickly.
As a wheelman, what would you do next?
As the tankerman on watch, what would you do next?
Step one should have already happened. In any critical operation, an escape plan always needs to be part of your operational toolbox. How do you react when the status quo changes? Are you ready to quickly assess a situation and make the right decision if something unexpected happens?
This escape plan must be part of your situation awareness thinking process. When evaluating an upcoming maneuver, gather critical variables (current, weather, traffic, etc.) and monitor surroundings as the maneuver is underway. Through it all, mentally prepare for a response to any unplanned contingency.
The deck crew must be ready to assess any electrical or mechanical failure with the system so the right response may be undertaken by the wheelman. Since time may be critical, understanding what to look for and where to look is key to stabilizing the situation.
But back to the steering failure. Where do you start?
To react properly to any failure, it helps that all crew members know your systems forward and backward.
Steering controls have changed over the decades of riverboat operation. In the early steamboat days, cables attached to the ship's wheel in the pilothouse operated via pulleys to the rudder in the stern. The larger diameter ship's wheels had mechanical advantage to transmit the pilot's commands to the rudder.
Today's Higman boats operate with "electric over hydraulic" steering.
What does this mean?
Quite simply, your movement of the steering stick or the joy stick is converted to an electrical signal that is sent to a series of open or closed solenoid valves that control hydraulic fluid flowing to or from the steering rams. The system will operate in two modes: "Non Follow Up" mode (NFU) and "Full Follow Up" mode (FFU). The modes are selected by the MODE switch on the pilothouse steering console.
Primarily, towboats operate on the "Full Follow Up" (FFU) mode.
FFU
Full follow up mode starts with the steering sticks. When the wheelman changes the position of the stick, the rudder begins to move and keeps moving until it reaches the ordered position indicated by the position of the sticks. To return the rudder to the amidship position, the sticks must be manually positioned to the centerline or zero degree position. The rudder position is sensed by a feedback unit located near the rudder quadrants. This allows the rudders to line up with the wheelhouse stick position.
The feedback unit also sends a signal to the rudder angle indicator in the pilothouse.
NFU
This is the most fundamental steering mode. This mode allows the wheelman the most direct control of the steering pump oil flowing into the steering actuators.
NFU uses the joystick control and causes the rudder to rotate port or starboard as long as the joystick is held in the left or right position. Upon releasing the joystick, the rudder remains stationary, holding position until the NFU joystick is again operated, or the steering mode is changed to a follow up mode. Setting the rudder angle to the desired position is achieved by the wheelman observing the rudder angle indicator and operating the NFU joystick left or right.
Evasive Actions:
If the boat losses steering while underway, follow this set of responses to help stabilize the situation and determine the problem so you can react properly.
With the system normally on FFU and your steering stops responding, what do you do?
The wheelman's response:
Alert the crew of the situation.
Switch to NFU and judge the reaction.
If the steering works, instruct the deck crew to check the feedback equipment. If the rudder angle indicator has also stopped working, it is probably a problem with the thin rod that connects the steering quadrant with the feedback equipment.
With the rudder angle indicator out, you may have to station a crewmember with a portable radio to relay rudder position to the wheelhouse to get the tow to safe mooring.
If that does not help, prepare to switch to the standby steering motor. If the maneuvering situation is critical, you may have to switch to the stand-by steering motor without verification of a non-leaking hydraulic system.
Alert area traffic of your steering failure. Prepare to ask for maneuvering help if needed.
The deck crews' response:
When alerted that the steering is unresponsive, grab a handheld VHF radio. It will be important that you can communicate quickly with the wheelman. In the wheelhouse, they should have already tried switching to the NFU control.
If NFU works, head to the back deck (steering flat) and check the feedback box, aft of the rudder quadrant. Look for a possible damaged rod that connects the rudder quadrant to the feedback box. This rod relays the position of the rudders to the system.
Look back at the wake. Is the wake matching the angle of the rudder? Relay information back to the wheelman.
If the wheelman says the NFU does not work and the system is still unresponsive, take a quick look at the steering flat for a leaking or broken hydraulic line.
If no leaks, head to the lower deck in the engine room. Look near the steering pumps for obvious hydraulic leaks.
If no leaks are visible, call the wheelman and tell him he can switch to the stand-by steering pump.
The wheelman's response:
Switch to the standby steering motor if there is no significant hydraulic leak.
If steering now works, have the deck crew look for obvious first motor problems:
Still no steering? Take actions needed to get to safe mooring.
Follow the decision tree below to help sort out the problem with your steering.