Summary of License
“The present invention is predicated on the realization that the combined functions normally assigned to the keel of a sailing yacht can be better effected without a conventional keel. Instead, a laterally swingable ballast is provided and carried on a strut, the portion of which is adjustable to provide the desired counter-heeling force, but which need provide no particular leeway control. Fore and aft underwater sailing foils of high efficiency and adjustable camber provide greatly enhanced steering and directional control, and further enable the yacht so provided to sail with controllable and adjustable leeway, which may indeed be zero.
More particularly, the present invention provides a keelless hull in which the hydrodynamic side force function (leeway control) and gravitational ballast function (angle of heel control) required for upwind sailing are provided by new and separated appendages. A heavy streamlined ballast appendage is mounted at good depth separate from and under the mid-body of the hull by means of a narrow strut swingable to port or starboard from a bearing in the hull to adjust the lateral position of the ballast and the amount of counter-heeling force. Fore and aft foils provide leeway, rolling and steering control, and roll damping functions which are structurally and hydrodynamically separated from the ballast appendage.”
CBTF is a patent protected technology. A simple license agreement based on the length of the boat will be required of the boat owner. The license fees are separate from design fees and are a charge for the latest performance technology.
Note: The contents on this website are subject to change.
The CBTF patents cover sailing yachts using a canting keel or ballast with fore and aft controllable foils or rudders to affect changes in side force and/or maneuvering, including sections with trim tabs and jibing daggerboards.
Full details of the patents can be obtained from the US Patent and Trademark Office website at
(reference patents No. 5,163,377; 5,622,130; 6,951,180 B2; 7,128,010 B2)
The information on the left is an excerpt from the “Summary of the Invention” from patent No. 5,163,377.
 License Fee Schedule -PDF
For more information:
CBTF Co., Inc.
+1 (619) 232-8664