IN ACTION Part of the plan in the digital system is to
identify the settings that need to be used at various stages of the passage. We recommend setting COG vectors and heading vectors to a meaningful length. Other settings that may need to change are cross track distance, waypoint arrival distance, or depth alarms. Set alarms intelligently and identify a sensible value for triggering alarms. By setting these parameters you’ll see where
you’re meant to be (the route), where you are (the vessel position) and where you’re projected to be. This is the minimum to monitor progress and identify if action is needed.
Execution and Monitor Execution of the plan has not really changed in the digital world. Ensure that answers
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and assumptions used haven’t changed sufficiently to require a fresh look at the plan. With a carefully crafted set of waypoints, it is easy to monitor progress along the plan and monitor the reliability of position. Take every opportunity to monitor your position by means other than the GNSS data. If you have a heading sensor, as recommended, it can be as easy as using the courser range and bearing feature to verify the bearing of a charted object or a rising/dipping light. Perhaps the easiest is using radar overlay. If the radar targets match charted objects, then the position is good. Remember, electronic devices can take
much of the drudgery and human error out of passage planning but the one who must ultimately make the decisions is the person acting as navigator.
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The new edition of RYA Day Skipper Shorebased Notes is
Chart display explained:
1. Vessel position: shows current latitude and longitude in degrees, decimal minutes and is usually from GNSS.
2. Speed over ground: measured in knots and derived from GNSS. 3. Course over ground: the actual direction of progress of a vessel, derived from GNSS. 4. Depth: measured in metres. Derived from an echo sounder which may be adjusted from the water line or under the keel. From vessel picture it’s most likely to be from water line. Plotters may show charted depth as chart datum or adjusted for tidal height. 5. Object info: ˔˗˗˜˧˜˔ ˗˘˧˔˜ ˔˕˨˧ ˔ ˦ˣ˘˖˜Ѓ˖ charted object or area. 6. Range Head SCM: is a named waypoint. It is the active waypoint, indicated by the dotted line and the text box on the bottom left. Not all chart plotters use this technique but they will all identify the active waypoint in some way. Location and name are set by
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rya.org.uk SPRING 2024
the navigator in the planning phase. Each waypoint should have a meaningful name and represent an action or decision that is needed. 7. Cursor position: shown as a range and bearing from the vessel, derived from GNSS in chart-only display. 8. Route: a series of waypoints joined to create a route. The route is set and named by the navigator during the planning phase. 9. Heading vector: shows heading from a compass ˜ˣ˨˧ʡ ¯˘˖˧˥˦ ˖˔ ˕˘ ˦˘˧ ˔˦ ˜Ѓ˜˧˘ ˕˨˧ ˧˛˜˦ ˛˔˦ been set to the distance the vessel is likely to travel through the water in 12 minutes (N-up Vector 12 mins, shown bottom left of display). 10. Course over ground (COG) vector: shows the direction of travel over the ground. Derived from ˝ˁˆˆ ˜˙˥ˠ˔˧˜ ˔˗ ˖˔ ˕˘ ˦˘˧ ˔˦ ˔ Ѓ˘˗ ˗˜˦˧˔˖˘ or a time frame, such as 12 minutes, to help with scale and projecting your vessel’s position.
available to order
(code G113). This version
covers the balance of paper-based and digital techniques for navigation.
Mobile devices play a part in gathering information to create a plan, but their small size will limit their use for primary navigation.
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