PLANING HULL A hull designed to ride across the top of the wter, rather than plow through
it (as does a dispalcement hull like a pontoon)
A boat hull has all sorts of shapes, bends, fins and grooves—things you can see most clearly when the boat's on the trailer. Surely, you've wondered: Why the hull do the makers do that?
Well, they do it because a deep-V hull is seaworthy but slow, and a flat-bottom is fast but flakey. Finding a blend of seaworthiness and speed has become a tantalizing challenge for some builders. Here's how a few standouts have gone about it with their own trademark design.
Stingray's Z-Plane Hull
Stingray president Al Fink once said his goal was "to make a boat as fast as it can be, but safe and easy enough for your grandmother to drive."
Stingray, which introduced its CAD-designed and patented hull in 1989, knows plenty about the pluses and minuses of the V-bottom boats with lifting strakes. Typically, lifting strakes are roughly parallel to the water's surface and the keel—until the boat turns, when they dig in and force the driver to slow down. They also create air bubbles in the water, reducing the propeller's bite. Lowering the motor helps, but that creates drag. Speed is lost.
The Z-Plane Hull minimizes these problems by avoiding right-angled strakes. The hull's running surface is actually three shapes nested, becoming steeper as they approach the chine. These running surfaces have strakes that vary from right angles by about five degrees.
The result? Less unwanted grab and ventilation in turns. The motor can be mounted higher, which reduces grag. Drive, Grandma.
The Stingray Z-Plane hull was feature in this story, along with 6 other hull designs.
by Steve Griffin
Boating Life Magazine