The first cat that Windrush made (and their highest number of sales) was a 12' "surf cat". Cheap, strong, great fun for kids or for TWO adults. They were used for years also for "off the beach" hire fleets - always sailed with at least one adult (for hire) and often with two adults and one or two kids (even though with more than one adult on board they suffered obviously with performance), but they did bring many many new people into sailing catamarans.
In the mid to late seventies I used to hire out a fleet of 30 of them over summer, off the beach here at Somerton/Brighton together with a 13’ cat that we made just for that business.