Shorebased


Never, ever, use an iPad for navigation… and other myths exploded!


N


ever, ever use an iPad for navigation – surely this is obvious to anybody who


has mastered the noble art of traditional navigation. What if the battery runs down? It doesn’t use official charts! It isn’t waterproof! In truth there are few arguments against using tablets that cannot be overcome. It could be connected to the vessel’s power supply, it could be in a waterproof case and there are apps that use official charts. It is common to see modern


vessels with little or no table space for chart work, the preference being a bank of electronic aids. Now that electronic chart plotters are common place on boats and navigation apps can easily be downloaded to phones and tablets, we need students to be able to identify which systems to trust and which require extra caution. Unfortunately there isn’t an easy list of approved/not approved as there is no design standard for leisure plotters or applications to be measured against. An added complication is that just because an app is well designed with an easy interface, it doesn’t automatically follow the underpinning navigational prowess of other more trustworthy sources. So, to get to the point, the RYA Training Plotter is intended to be used to help students to: » identify the traits to look for in electronic charts and chart plotters,


» assess the extent to which any given system can be used,


10 | www.rya.org.uk


» be able to make appropriate use of electronic chart plotters in the appraisal, planning, execution and monitoring of a voyage.


If you consider the relationship between the shorebased and practical courses it is reasonable to suggest that the shorebased course is predominantly about teaching students how to appraise and plan voyages, with due consideration for the execution and monitoring phases. The practical courses consolidate the appraisal and planning stages but are really about developing the execution and monitoring. To use a simple example, when planning a route, shorebased training requires you to place waypoints in locations that can be verified independently of the satellite derived fix. On the practical course the instructor hammers home the importance of this independent verification and helps to refine the placing of these waypoints based on practicalities.


The RYA Training Plotter is


designed with this division of training in mind. It is predominantly about the appraisal and planning stages, with some execution and monitoring. To start the ball rolling there are


three questions that we should encourage all students to ask themselves when looking at any data, be it electronic or not. 1. What exactly is it telling me? 2. How reliable is the information? 3. How am I going to use this information?


The answers to the first two questions really drive the answer to the third. With an electronic chart plotter there are two distinct elements to assess: 1. the electronic chart itself 2. the plotter’s functionality as a navigational tool.


Let’s apply them to an electronic chart first. We’ll use the one in the Training Plotter, as shown below, and pull out what a student should be able to read and understand from this display:


What exactly is it telling me? 1. It is showing an Electronic Navigation Chart (ENC), an Approach chart to be precise, at a scale of 1:22,000. It is chart edition 1.001


2. The display is over-zoomed by 1.5 times the compilation scale, so it is zoomed in beyond the level of detail available for the compilation scale.


3. The Zone of Confidence for the data within the green highlighted section is A, so the tolerance of charted depths is estimated to be within +/- 5%. The zone of confidence areas are the digital equivalent of the source data panel on paper charts.


4. The chart layers for spot depths are turned off (the ‘Anchoring mode’).


5. The depths are in metres, distance in nautical miles and positions are expressed in degrees and minutes.


6. Bearings are expressed as True


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