Rob copied the photo and text of the Marstrom 20 above from the European website link that is given with it. Just for the sake of clarifying terminology, I believe that device shown is for spinnakers rather than gennakers. At least in my own understanding, a gennaker (genaker?) is a cross between a spinnaker and a genoa jib and is basically the same thing as a reacher or screacher or hooter in that it is attached and sailed more like a big, full, overlapping, roller-furling jib than like a spinnaker, which is lowered when not in use.

Possibly the terminology is different in other parts of the world, and perhaps some people use the term "gennaker" (or genaker) to refer to an asymmetric spinnaker? I don't know. Rob says his understanding also is that the Marstrom device shown is for spinnakers and not gennakers.

Anyway, this instance is an example of the reason why Rob and others, especially from overseas, have suggested that we have a complete glossary of sailing and catamaran-specific terms so everybody knows what everybody else is talking about. It would also be helpful to translators who are doing English-language versions on websites in other countries.