El Cid - By Hal Kelly. Build this sportboat in days for less than $100. It’ll provide hours of safe fun for youngsters of all ages. El Cid is a mini inboard hydro that’s powered with a 4 H.P. air-cooled engine. Its top speed is about 16 mph with a 100 lb. teenager aboard. It features a “dead man’s” throttle that shuts the motor when the driver lets go of the throttle, so there’s no danger if the operator falls off the boat. Safe enough for an eight-year-old, it’s a great little boat for the young to start out on. Use is limited to well-protected waters, of course.