Luggers are designed for fishing.

Conventional sailing boats have a mast and a boom attached at the bottom of the mast - the boom runs along the middle of the main deck - and the sail is a triangle.

So the main deck is cluttered with the boom, rigging and winches - very good for sailing but not much good for anything else.

Luggers have a yard that is hauled up to the top of the mast. The sail "Lug" is attached to the yard and has 4 sides.

The lug is hoisted using the halyard.

The result - the main deck is clear of clutter and is available to handle the fishing nets and fish.

You can see the mast, yard and lug sail in this picture.

 

And you can see that the mast is secured by a single rope - the "burton".

Happy Return is rigged as a "dipping lug".  This makes for some exciting sailing.  When you need to change course - the sail and lug are hauled down and transferred in front of the mast from one side to the other.  Similarly, the burton needs to be released and transferred to the other side.  Typically a job for 4 crew members.