Originally Posted by Semper Fi

Like you knew this also ....you just got schooled when you found this info on the net

Originally Posted by Back4More

You got it!

Originally Posted by gotime34

Interesting stuff there guys...that was a hell of a history lesson, thanks for the info.
I was looking more for the progression of stepped hulls through the last decade. How come most manufacturers are making stepped hulls now, but some aren't, such as Sonic?

Originally Posted by Back4More

You guys know nothing.... Stepped Hulls

The concept was originally proposed by Rev. Ramus of Sussex England in 1872. He proposed both a single step with tandem planing surfaces, and a combination of three pontoons with one forward and two aft. Indications are that these shapes were derived from model tests. Unfortunately, the heavy steam power plants of that day could not push a hull fast enough to plane, and take advantage of the new concept.

As early as 1906 there were published drawings for small stepped hulls with hard chines. William Henry Fauber [8] obtained a U.S. patent for hulls with multiple steps in 1908, but could find few people in the U.S.A. interested, so he moved to Europe.

Two small boats Solair (12') and Flapper (15') demonstrated the potential of stepped hulls as did the Harmsworth challenger Pioneer (5 steps) in 1910. (See Data Chart, Figure 12.)

The stepped hull began practical development about at the same time as the hard chined planing hull. A step in the bottom of a hull, raises part of the bottom surface so that it is no longer touching the water. Less wetted area. At the same time, the planing surfaces meet the water at a near optimum angle of attack over a wide range of speeds. The stepped hull is very efficient hydrodynamicly.

In the early days of stepped hulls, it was not certain just how many steps should be incorporated. Pioneer had 5 steps in 1910. Maple Leaf IV had 5 steps.

Maple Leaf IV: Length 39'-11" x Beam 8' . Two V-8 engines 350 Hp. each.

In 1912, Maple Leaf IV came over, from England, won the Harmsworth Trophy, and took it home. She had no less than five steps, and the driver sat on a pedestal high above the transom in order to see over the bow.

Some hulls had so many steps that they were called "shingled'. Rainbow IV (12 steps);

Eventually, model tests showed that a single step would be most efficient if you could locate it in the right position and give.it the proper depth.

The lines shown in Figure 10 are typical of stepped hulls in the 1920's. Note the very flat bottom. This boat raced in a class limited to engines with 1.5 litre displacements.

Gar wood brought the Harmsworth Trophy back to United States in 1920 with the first of his Miss America's. These single stepped craft so dominated the Gold Cup and Harmsworth racing that few other boats attempted to compete. The Miss America series were not really efficient boats, just big boats with huge amounts of power from multiple V-12 Packard engines.

Between about 1915 and 1940, a great many motor torpedo boats and fast patrol boats were built world wide, with stepped hulls. [10] The performance of these craft varied considerably, with some being very inefficient.

Stepped Hull Limitations

The stepped hull maintains a nearly optimum angle of attack over most of the speed range. The hydrodynamic hull drag is almost constant. The drag of the propeller shaft, shaft strut and rudder, (appendage drag) increase as the square of the speed.

The graph of Performance Factors shows actual speed data of different prominent racing stepped hulls. The data points are numbered and refer to numbers on the data chart Figure 12. The boats are numbered in sequence according to the year when the speeds were established. The sequential increases in power factor reflect engine development and not hull development. Notice that most of these boats perform almost on the limit line. Gar Wood's Miss Americas were really quite inefficient. Many stepped hulls from England were significantly more efficient and often faster. They failed to win races because of a lack of strength and mechanical reliability. The very streamlined Alagi was slightly more efficient than the others.

Stepped hulls are difficult to design. There are many design variables compared to the design of a Vee bottomed monohull. I do not know of any accurate method available to optimize stepped hull design other than by model testing.

Stepped hulls dominated race boat design until about 1938 when Adolph Apel patented the three point hydroplane configuration. Ventnor three point hydroplanes dominated small limited class racing, yet stepped hulls were running competitively in Unlimited class racing up until 1949. In 1950, Slo-Mo-Shun demonstrated 'prop riding' and boosted the world speed record significantly. (More on 'prop riding" later.)

Stepped hulls definitely have the potential of being significantly more efficient than rnonohulls.

Compare the Limit Lines on the Performance Factor graphs. There are a number of reasons why stepped hulls did not become popular for pleasure boats.

(a) Complexity of design, and the costs of development.

(b) Stepped hulls were banned from gold cup racing from 1920 to 1931. Wealthy race boat owners were not investing in stepped hull development.

(c) There were quite a few relatively small stepped 'gentleman's racers' built, but few of these were really efficient.

(d) There were many huge war-surplus aircraft engines available after the first world war, at reasonable prices, and few light weight marine engines available. It was easier, (and possibly cheaper) to buy a big engine for a monohull, than to develop an efficient stepped hull.

OSO....You have been schooled

Originally Posted by skopi55

Fountain went to the stepped hull in 1995. 1994 was still a flat bottom boat.

Originally Posted by PatriYacht

Hustler had a stepped 40 in 1989. You could get it with big power and Arnesons too.

Originally Posted by jb

Obsession has one in the early 90's, I doubt that was first....S. Stepp had to have his hand in there somewhere...