This catamaran was built by martijn boon from andijk – the netherlands. martijn is a welder and machinebuilder who also likes to design and built special. Open/dayboat, free sailboat plans hobby kat. everyone who digs boating has heard of the hobie cat, the sleek little catamaran that burst on the scene and captured the. Construction is stitch & glue plywood, well within the ability of most amateur builders. the rig uses aluminium, grp or carbon tubes for the free-standing mast but.