Chart correction tips
In this section, we want to share a little bit of our experience in chart corrections.
The following examples are one way to perfom them.
We hope to ease your task when comes the time for you to update your charts.
This page can be considered as a complement to the ADMIRALTY NP 294 “how to correct your charts the ADMIRALTY way”.
We use ADMIRALTY notices to mariners printed on tracing paper in our examples.
ADMIRALTY Videos regading chart updates are also available on The ADMIRALTY TV
Chart corrections tips
• 0.25 magenta pen, the only one authorized for chart corrections
• 2B pencil and eraser
• A screw: my option to mark the corrections positions on the charts (7H pencil is recommended by the ADMIRALTY)
• A compass where the magenta pen fits
• A ruler and a circles template (very useful)
• A NP5011 (when i have a memory loss on symbols and abbreviations)
• Tracing paper to print the corrections
• chart availability list to check the last edition date to prevent correcting a withdrawn chart
• www.nmwebsearch.com webpage to see all the nms for a chart reference
• NP133A, the chart maintenance catalogue to record all the updates per chart
• Notices to mariners
My tools for chart corrections
In this section of the charts you can see:
• The last edition date of the chart. This can be verified in the chart availability list. if your chart is older then it need to be replaced as it is not safe using it due to possible changes affecting the area.
• A QR code that redirect you to the www.nmwebserach.com web to see the all the notices to mariners numbers for this chart reference.
• All the notices to Mariners nº applied on the chart should be written after the text “ADMIRALTY notices to mariners updated to”.
As you can see on this picture, the last corrections made on this chart is dated 2018 and the notices to mariners nº is 6189.
Bottom left of the chart
At the bottom of the chart you will find a succession of underlined value (Years) and notices to mariners numbers. If the last number on your chart correspond to the last one the nmwebsearch webpage, your chart is up to date (it is recommended to check if all the numbers are the same)
if it is not the case then you have some work to do!
The notices to mariners update list
1. Chart reference (or nº)
2. Chart Edition date
3. Correction position in the chart
4. Current notices to mariners number
5. Previous notices to mariners number that should appear on the bottom of the chart
6. ADMIRALTY charts are grouped in Folios which represent an area on the map. In this example, Folio 25 is part of the mediterranean.
Make sure to always check that the previous notices to mariners number is written at the bottom of the chart. if not it may be because the update is not done or just an oversight
Top section of a tracing
To avoid overlaying or deleting information, we draw our buoy in clear space.
A non direct arrow will connect our buoy to it’s position.
Arrows on ADMIRALTY charts have specific signification. It is recommended to use S type arrows in this type of situation.
Mark the buoy position on the chart
The buoy should be drawn in this exact
position.
position the tracing paper on the chart.
BUOYS
With the tracing positioned on the chart we can see the lack of space to draw the buoy.
We use a 7H pencil or other tool to mark the new buoy spot.
As we have a clear space just above our mark, we can draw our buoy there and connect it with a non direct arrow.
New objects should always be at 2cms radius max from their spot.
Buoys
Example 3 : deleting a buoy
The symbol pointed by the red arrow means DELETE.
It is used on the tracings to identify the object and it’s characteristic we have to remove.
It should not be drawn. two simple lines as shawn in the picture are enough. We recommend to use the ruler for a clean job.
Buoys
Double lines to delete buoy A4 and A5.
Undirect arrow to tie the buoys to their positions when lack of space.
We have to insert and delete several buoys.
the tracing show the positions for the new buoys and the ones that need to be deleted.
Buoys
Several depths to insert and others to delete in this correction.
In the first picture we can see the positions for the new and the ones that we have to remove.
Mark the positions, they are signalled by the red arrows in the second picture.
Always do the insert before deleting anything, sometimes the info we have to delete can be usefull for the new info we have to insert.
Use non direct arrow to connect the depths to their positions when lack of space and double lines to delete the others.
Depths
An enclosed depht as to be updated to the value 19.
Drawing a little circle in the center of the enclosed depth will determine the position of the new value.
Short lines to delete the old value.
A non direct arrow wil connect the new value to the center of the enclosed depth.
Depths
We have to add a new marine reserve limit on this area.
We first mark the different lines intersections leaving space for the «MR» caption.
We then connect the dots with discontinued lines.
Remember to never write on existing information.
Cables and lines
In this example we will have to draw an electrical cable and 2 water lines.
Mark the lines positions.
Draw a guideline for the power cable with your 2B pencil.
Hacksaw blade can be used to draw the cable to gain time.
We don’t use it as it end up deteriorating the magenta pen.
Delete the pencil line and write the captions for the water supply.
Cables and lines
This update is about drawing a prohibited entry area.
We mark the circle position and it’s diameter.
Using the circle template, we can draw our picked line leaving space for the “forbiden” symbols
Once the big circle is drawn, we can use the template again for the signs.
Circles
In this example we will have to draw an electrical cable and 2 water lines.
Mark the lines positions.
Draw a guideline for the power cable with your 2B pencil.
Hacksaw blade can be used to draw the cable to gain time.
We don’t use it as it end up deteriorating the magenta pen.
Delete the pencil line and write the captions for the water supply.
Cables and lines
