IN ACTION eNavigation
Passage planning in the digital age
Soon the sun will set on some paper charts; we ask which skills should we develop and which may become redundant
T
he four stages of passage planning and making still apply when navigating with electronic equipment: Appraise, Plan,
Execute, Monitor. In almost every way, once you have mastered your onboard system and identified your go-to sources, passage planning can become infinitely quicker by letting the electronics do the heavy lifting.
Appraise
There are new skills to learn, new equipment to master and new sources of information to explore, but the human gathering the information will still need to link pieces of the puzzle into decisions and a plan. The
information in publications such as Reeds Almanac or pilotage guides will still be relevant, but in future it may be presented in a digital format, or within electronic charts. In this lies not only great benefit but also hidden dangers. Many manufacturers have their own operating system, terminology, user interface and even chart formats. We’ll need to develop skills to identify systems and sources that we trust or simply prefer. Screen size will be a limiting factor. A mobile phone charting app may be useful for bigger picture overviews of an area, but the limited screen size increases the risk of missing detail. It’s also predominantly deriving its navigational information from a single source – Global Navigation Satellite System (GNSS). The golden rule that navigators should not rely on one source of information remains true.
Plan
This should cover the full voyage from berth to berth. When creating a plan we need to place waypoints and routes in such a way that we can independently verify that the GNSS position is accurate. This independent verification is essential for spotting when things aren’t right. We can use Dilution of Precision numbers
as an indication of likely precision and on more modern systems we may have a traffic
light system. Whilst electronic methods indicate reduced precision, they don’t tell you what that means in terms of error in position. This is where pilotage routines using visual, compass, depth or radar techniques remain valid.
Building a route in your electronic
chart systems (ECS) is essential to monitor
progress against your plan. The most common ways to
manage lack of screen space is to use
rubber banding or auto-route. Rubber banding is the practice of starting with the first and last waypoints, then working forward from the start waypoint to place additional waypoints as needed. Auto-route is implemented differently in each brand of ECS, from using minimum depth required to all vessel dimensions. The autoroute will usually be created by entering start and finish waypoints and the ECS suggests a route. We should never use an auto route without checking each waypoint, adjusting its position or adding or deleting as necessary to ensure the route is correct. If you cannot adjust the waypoint on your system, stick with rubber banding.
The route in itself is not a plan, and you cannot create a route until you have identified all the limiting or significant factors. When creating the route, we can incorporate much of the additional information needed for a plan – each waypoint should mark an action or decision to be made.
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dentified When
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“The digital system plan helps identify settings needed for various stages of your passage”
rya..org.uk SPRI SPRING 2024 45
org.uk Using
electronic equipment can aid speedier planning, as long as you’re not relying on just one source of data.
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