Welcome to the third part in the Shore and Ocean Effects for Overland Maps series.

In this part we well be focussing on adding rhumb lines to beautify a relatively smooth ocean texture.

Arumnia, the example map used in this tutorial, was drawn in the John Roberts overland style, which was recently included with the core CC3 app as part of Update 25.  If your software is up to date you do not need to own any of the annuals or add-ons to make use of the FCW file included in this blog.

Portolan Charts

The first maps created of the real world that contained rhumb lines were called Portolan Charts.  Rhumb lines were an important and practical part of the map.  However, in more modern times thanks to modern navigation aids rhumb lines are no longer necessary and have largely disappeared from our ocean charts.  Meanwhile, they have become an increasingly popular part of fantasy maps, though mainly as a decorative element to enhance the appearance of the map and give it an older appearance.

Rhumb lines usually radiate out from a simple compass-like rose along the 32 points of the compass which we can draw quite easily using CC3s basic shape drawing tools and a few simple commands that are conveniently available from the menus.

Constructing the rhumb lines

It is best to use a style that has a relatively smooth ocean texture as the background for this project.

Hide all the sheets except the BACKGROUND of your map, and if you haven’t already got one add a new sheet called NAVIGATION LINES just below the BACKGROUND sheet in the list.  Make sure this is the active sheet, and that the NAVIGATION LINES layer is also selected.

Right click the GRID button at the bottom right of your screen and pick a suitable grid.  I’ve chosen the 10 mile, 1 snap grid, which seems to work well in this exercise on a default overland map of 1000 x 800 map units.  Whether you go larger or smaller than this will depend on the overall size of your map.

Turn on the SNAP and GRID, and with the Line tool set to use a line of zero width and a suitable colour for your rhumb lines, draw a vertical line from somewhere near the middle of your map to the top edge.

Right click the Copy tool on the left and pick Circular Array from the drop down menu.  Pick the line you just drew and Do It.  The line will go pink and nothing else will seem to happen, but check the command line at the bottom of your screen and you will see a prompt asking you for the Number of spokes.  The default is 1.  Type 32 on your keyboard and hit the Enter key.  Next you will be asked for the Number of rings.  Leave that set to 1 and hit the Enter Key again.  Now CC3 is asking you for the Array Centre.  Click once on the end of the line in the middle of the map.  Then you will be asked for a Copy Origin.  Click once again in the same place as last time.  Finally, you are asked to approve the Angle between spokes.  Hit Enter on your keyboard.

The result should look something like this (right).

As you can see, a simple design choice was made when rhumb lines were first ever used to avoid the nexus of ink that simply crossing them in that one place would have caused.  It would have been the darkest spot on the map by a very long way.  So instead of allowing such a massively distracting structure early mappers joined the lines to a circle instead of crossing them over.  Whether these circles were intended to represent compasses or to be called compass roses is a matter of debate, but that is how we see them today.

Before you draw your own compass rose make sure that your fill style is set to Hollow.

Pick the Circle tool on the right and zoom in to the centre of the crossing place enough to be able to draw one hollow fill circle of approximately 60 map units in diameter with it’s centre placed where the lines cross.

Go to the Edit menu and pick Trims->Trim to entity.

Pick the circle first.  This will highlight it pink.  Then click each of the radial lines outside the circle.  This will cause them to be trimmed up to the circle.  Right click once when you have finished and click refresh.

Your drawing should look a bit like this (right).

If you wish to make a more complicated rose like the one in the example map, you might need to draw more circles, beyond this one and trim every other rhumb line to thin them out a bit more near the centre.  The final design is your choice, but if you have had quite enough of drawing and trimming this simple rose is good enough.

Once you have finalised the design of your rose and rhumb lines go to the Tools menu and pick Groups->Group.  Select all the lines and the circle and Do It.  This will make it easier for you to move the rose and rhumb lines around your drawing until you find the right place.

Placing the rose

Reveal the rest of your map and use the Move tool to pick up your new rhumb lines and move them around the map to find the right spot in the ocean.  Rhumb lines often pass through places of importance on the coast (though this is not essential), and the rose itself is usually placed somewhere where nothing else will obstruct it.  Since our rhumb lines are decorative more than functional a certain amount of artistic license can be used in the placement, so don’t tie yourself to those rules.  The rose in the example map doesn’t show any rhumb lines going through important places on the coast, and the rose itself is obstructed by one of the islands and an ocean label.  I put it there because it looked good.

In case you are wondering, there are several sheet effects on my NAVIGATION LINES sheet.  These are glows and blend modes designed to make the lines more subtle so that they do not entirely dominate the map.  These effects can be examined first hand if you download the FCW file here.

Finishing the job

There is just one more thing that we have to do to make our rhumb lines perfect, and that is to trim them to the edge of the map.

Make absolutely sure you have the rose in exactly the right position.

Hide all the sheets except the BACKGROUND and NAVIGATION LINES sheets and fetch the same trimming tool you had earlier from the Edit menu.  Click the Locked button on the bottom right of the window so that it shows as Unlocked and pick the background as the Entity to trim to. Proceed to click each of the radial lines in turn to make them grow outwards to meet the edge of the background.  Right click to finish and click the Unlocked button to re-lock all the groups of things in your map.

You should now have a completed rose and rhumb lines on your NAVIGATION LINES sheet, to which you can add your own choice of sheet effects.

I have enjoyed making this rose and rhumb lines for you.  I hope you get just as much fun out of it as I did 🙂