peller." The bi-foil skeg acts like a passive trim tab to lift the stern at hull speed and beyond giving a seven percent reduction in resistance. It reduces pitching motions at the stern by 30 percent. Bray's most recent advancement comes through the use of significant appendage fairings. Having reduced the bow wave with a fine entrance angle and the use of a bow bulb, Bray turned his attention to reducing the midship hollow. It was reasoned that this would help reduce drag by reducing the overall wave train and would increase stability underway by reducing the midship hollow. Although this technology is still very new Bray said he has achieved a maximum reduction of six percent drop in resistance over a range of speed from eight to 16 knots with no resistance penalty on up to 20 knots. He believes there is potential shown for reductions up to 10 percent. The volume of the appendages accounts for 15 percent of the vessel displacement. This allows the hull form to be finer, narrower and shallower, reducing hull resistance even further.
Where is Bray's research headed next?
"With the reduction in bow and midship waves it is only natural that we should look aft to the transom. The large reduction in bow wave needs to be matched by a similar reduction in the stern wave. The exact parameters are undergoing study and there are several areas of work that hold promise, including stern bulbs. To date stern bulbs have shown as much as seven percent reduction in resistance." "The ultimate goal is to have a vessel that will slip through the water without any disturbance to mark its passing � the ultimate interface vehicle. We are continuing this work on many of our new projects, particularly focusing on 100-ft plus long-range motoryachts."
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