Minimost, the playmate for the Minimax - By William Jackson. Five evenings building, $50 for materials and then comes the real thrill of owning and running your own 8-ft. outboard sports hydroplane. Minimost hydroplane was designed as a low-cost playmate for the Minimax, Science & Mechanics most popular sport boat. By using stressed-skin construction and advanced under-hull design, however, it's been possible to wring more speed out of the same size hull. When fitted out with outboard motors in the 10 hp class, you've got speeds well up into the 30-mph range.