Inkscape strategies: line/paths vs. calligraphic tool

[FabioCapela]

I did a little experimentation with Inkscape's calligraphic tool, but found i difficult to draw a whole coastline in one go (I'm working with a mouse here!),

You can always increase the "mass" setting of the calligraphic brush; it should make the line much less sensitive to mouse jerkiness.

and failed miserably in trying to figure out how to join up the separate shapes created by drawing the coastline in multiple sections into one continuous calligraphic shapes.

Select all individual shapes and press <ctrl> + <+>. You might need to edit the nodes in the junction to make them smoother.

I decided it would certainly be much easier to just draw simple freehand lines that could then be edited and tweaked into shape if desired. It was easier to figure out how to join up different sections of simple lines! But now I wonder if there's a clever way to transform a simple line path into a calligraphic shape that follows the line? So, basically, the idea would be to draw a complete outline as a simple line, but then apply some transformation that made it as if I had drawn the complete line using the calligraphic tool?

Select the unified line, duplicate it (ctrl+d), move the copy a little to the side, select both the original and the copy, join the shapes (ctrl+k), create an edge between the ends on both side of the line and fill the shape with some color.