Boatbuilders and designers of stepped hulls walk a fine line between getting the most speed out of a boat and making it manageable at high speed. Donzi got it right with the latest incarnation of its 38 ZRC.
The 38 ZRC first debuted five years ago as a twin-stepped model. In 2007, the manufacturer redesigned the bottom by adding shorter steps to further break adhesion to the water, which improved efficiency. With a pair of 700-hp Mercury Racing HP700 SCi NXT-1 packages, the boat ran 114 mph in windy conditions. In midrange acceleration tests, the boat ripped from 60 to 80 mph in 7.6 seconds and from 70 to 90 mph in 8.6 seconds.
The first step is 2½" tall and starts right under the quarter F-16 canopies, at about the 17' mark. Abaft 2'11" is a ½" step followed by another taller step that's 3' aft. The final ½" step is 3'8" farther back. Lifting strakes set close to the V in the forward section of the running surface help get the boat on plane quickly. Once the 38 ZRC is up and running, it rides on a keelpad with a shallow V. An 8"-tall transom notch spans between the outer strakes.
In washing machine-like conditions, the 38 ZRC has a reassuring feel. The boat carves smoothly through circles at 75 mph and zigs and zags through slalom turns up to 60 mph. Even at 100 mph the boat responded well to evasive maneuvers.
When you get in big water, you'll appreciate the 38 ZRC's heavy-duty construction. The bottom has a 1¼"-thick composite core with extra stiffening in the sides and deck. Stringers are composite cored forward of the engine compartment, and those beneath the motors are cored with marine plywood. The hull-to-deck joint is sealed with a methacrylate adhesive and bonded around the inside perimeter with fiberglass.