People shopping for a boat frequently ask us about deadrise. Usually, they're comparing two or more boats and want to know how a difference in deadrise affects the relative performance of the two boats.
It's an excellent question and one with no easy answer. The debate in yacht design circles and among boatowners has raged ever since Ray Hunt and Dick Bertram built the legendary Moppie in the 1950s and smashed the offshore racing record book. Now, almost 50 years later, the answer to your question about the effect of deep-V hulls is still elusive.
What is deadrise? It's the angle of the boat's bottom relative to the horizontal. A flat bottom boat has a deadrise of 0°, while a deep-V might have a deadrise of 25°.
The first part of the answer in determining how deadrise affects performance is another question: deadrise measured where? If the angle between a horizontal plane tangent to the keel and the chine is measured just aft of the bow, most modern boats will measure around 45° or more. If measured just forward of the stern, the deadrise may be as little as 5°. The days when deep-V hulls carried the same high angle of deadrise nearly constantly from bow to stern is long gone. Why? Because they didn't perform very well.
What was learned in the period from the late 50s to the mid-70s is that deep-V hulls do indeed slice through rough water at high speed better than any other design. But they're fuel hogs because they have so much more wetted surface, demanding huge horsepower to drive them through the water. They also have limited initial stability, meaning they tip more easily as loads are shifted (thus the trim tabs and the designation of "a flat-bottomed boat with two chines on one side"). Steering on a deep-V boat is usually erratic at low speed and they tend to "porpoise" at high speed in calm water.
Despite all these inefficiencies, designers began to experiment with alterations of Hunt and Bertram's early successes, mostly due to a public misperception that the deep-V was faster than earlier designs. But note the exceptions. For boats used exclusively in calm water, especially where draft was important such as with flats boats, nearly flat bottoms were still used almost exclusively. There were variations on this theme with tri-hull, airslot, tunnel-drive and purely flat-bottomed boats in profusion. The latest craze for catamaran hulls is an extension of this heritage. Most high-performance bass boats today still reflect these traditions and are still favored where the waters aren't rough.
Look at the geometry of the 3-dimensional hull in cross section by taking a slice of the hull through the middle. We have a vessel of a certain height from the horizontal plane of the keel to the horizontal plane of the chine. This locks in our deadrise angle at say, 21°. Now we decide that the hull is too narrow but we don't want to increase the draft. If we just give our design a wee bit more beam, the deadrise angle may just decrease to 18°. Then look at the way the angle is carried aft by taking some more slices of the hull further aft. Is the angle still deep near the stern? Or did the designer provide more buoyancy and form stability there to support a massive power plant right at the transom?
Now look at the hull in profile. Is the keel a straight horizontal line from the turn of the bow to the transom? Or does it get progressively deeper as it goes aft? Or does it have "rocker," having its maximum depth about midhull and then becoming shallower and flatter as it goes aft, actually forming a slight curve? All these design elements will affect the performance of the boat as much as the maximum deadrise angle. In fact, in the early 70s when SeaRay and others were attempting to perfect the modified deep-V hull, there was a lot of talk in design circles about the "X-Factor," the attempt to get the combination of "V" forward, flatness aft, and keel rocker combi | 
