Designing for high-speed ships
Doctoral thesis
Permanent lenke
http://hdl.handle.net/11250/2453964Utgivelsesdato
2007Metadata
Vis full innførselSamlinger
- Doktorgrader [13]
Sammendrag
Fast patrol boats are high-speed vessels operated by the Royal Norwegian Navy
(RNoN). These ships are 36,5 meters long, have a beam of 6,2 meters and operate at high speed (32 knots – 16,5 meters per second) in very restricted waters. The fast
patrol boats are war ships and navigation tasks performed by the crews are different
from those in civilian high-speed craft. A team of five persons navigate the fast patrol
boats, and navigation is based on traditional means such as visual observations and
paper charts. The person leading the team is the navigator.
The ships were built in the late 1970s and upgraded in 2001 when new navigation
equipment was installed. However, the crews criticized the modern navigation
equipment for being complex and difficult to use. In 2002, an upgraded fast patrol
boat collided with a rock during high-speed navigation. The accident resulted only in
material damage. Following this accident the RNoN acknowledged the need to gather
knowledge about human factors and design of navigation equipment.
Navigating a fast patrol boat is about operating a complex socio-technical system.
Strong demands are put on both people and their tools. In order to design usable
navigation equipment for these ships, one has to have knowledge about the ships’
task, the crew that carry out the navigation, and the contexts in which navigation
takes place. To gather such knowledge, this study observed several navigation teams at work and used different approaches to structure and describe the work of
navigation teams.
A hierarchical task analysis was conducted in order to describe navigation in accordance with procedures and established best practices. The assignment navigate to destination was the highest level of the navigator’s work. The assignment included the navigation tasks; plan, start, monitor, change course, and arrive. For each navigation task, a detailed analysis was conducted. It was found that the crews used work practices that emphasize efficiency rather than accuracy in e.g. position fixing. Although efficiency was given priority, the navigation teams controlled system
variation in order to keep the ship within safe waters.
A usability study was conducted. This study treated navigation equipment that had
been fitted when the ship was upgraded. A cognitive walkthrough was conducted in
order to evaluate whether human factors guidelines were applied in the design of the
modern navigation equipment. In total 30 usability findings were described. The
study suggested that navigation equipment to little extent were user-centered. The
navigation teams compensated for lack of usability by expanding actions and by
modifying the equipment.
The framework of distributed cognition was used to describe the observed work of
the navigation teams. Distributed cognition suggests that cognitive processes are not
bounded by the individual person, but are distributed between humans and the
physical artifacts they use. Humans and artifacts that participate in goal directed
processes are said to be in a functional relationship. Within the functional
relationships information trajectories describe how information is gathered, shared
and used. Functional relationships are not static but can configure depending on the
context. In studies of distributed cognitive processes, investigating physical
representations are important as these are outside the head of the people, yet within
the cognitive system.
The navigation team and their artifacts were described as one cognitive system where the crew and their tools were functionally related. Navigation was in most cases founded on a detailed plan. The navigator drew lines and symbols in nautical paper charts in order to represent the plan. The navigation plan was a resource for the teams’ actions and the charts were a frame of reference for the teamwork on the
bridge. The crew enriched their tools in order to improve communication and information retrieving. For instance, information important to navigation was to large
extent noted in the chart. Another example was equipping the bearing device with
small pins in order to feel the direction of the device. Artifacts were also used to
support the navigators’ memory. Pointing the bearing device in the direction of the
upcoming course meant that the navigator did not have to remember the sailing
direction. The dynamic properties of the system did on the one hand provide barriers
towards erroneous actions. The crewmembers monitored each other’s tasks and
corrected mistakes when necessary. On the other hand, when the functional
relationship was not held together, the result was entropy.
The framework of activity theory was used to provide further descriptions of the
navigation teams’ work. Activity theory focuses on people working in a context. In
this study, activity was regarded as situated actions taking place in shorter time
frames. Activity theory claims that the elements of the activity encompass the persons and their use of tools towards a conscious goal. Further, the goals of the activity are influenced by the outcome of the activity and by specific constraints.
Activity theory describes the structure of navigation at different levels. The basic
constraints that influenced the navigation teams were related to the space available to maneuver the ship, and to the conditions for making visual observations.
Crewmembers’ behavior was not constant, but directed towards different motives
depending on the circumstances. The crew usually carried out goal related tasks.
However, in some cases the crew directed their work towards the operations of
equipment or towards solving problems. The framework of activity theory described
how internal and external factors influenced the focus of the teams’ work.
Both distributed cognition and activity theory findings suggested that the teams
frequently used artifacts for purposes beyond their initial scope of design. For
instance, bearing devices were used to augment navigators’ memory.
Based on the knowledge gathered from task analysis, the usability study, and from
the frameworks of distributed cognition and activity theory, a design study was
carried out. Four prototypes were produced in order to explore possible design
solutions that could improve the thinking and cooperation for the navigation teams.
The prototypes included an automatic steering system, an electronic chart, alarm
panels, and audio alarms. The prototypes emphasized the use of physical
representations and perceptually rich interfaces. The interfaces used for instance
sound, vision, and tacitle feedback.
Applying human factors principles in design suggested several design solutions that
possibly could improve navigators’ working conditions. However, there is a risk that
new design will create opportunities for new types of failures. For this reasons, user
evaluations were suggested as a necessary part of design development. However, user evaluation was outside the scope of this study.
This study suggested two outcomes of a design processes. One outcome is the
improvement of the design in question. The second outcome is the design seeds, that is concepts and techniques that can be reused in other development settings.
Development on navigation technology is at present an industry with strong
engineering influence and traditions. This study suggested that a user-centered
approach should involve engineers and work through the engineers’ domain. It was
suggested that a design process for development of navigation equipment would
benefit from being multidisciplinary, iterative and utilize user evaluation.