Lets hope this larger thumbnail works: (Click on this image, then again on the next image that appears and it will grow again!)
Hobie, being a sailboat manufacturer for so many years, was naturally well versed in all the nautical terms. So when the Mirage drive first appeared, they had to come up with names for all the parts. Since the fins reminded them of sails, they so named them and all the parts took their names from sail parts. For instance, the metal rod for the fin is called the
mast. The rearmost attachment point of the fin is called the
clew. The
outhaul block, which the
clew normally attaches to is symbolic of what you would find in the corresponding position on a sailboat.
So, Avast, matey, once you get your sailing terminology down, twill all make sense!