(a) The zones and areas in this subpart are, in general, based on the following criteria: (1) Summer: not more than 10 percent winds of force 8 Beaufort (34 knots) or more.(2) Tropical: not more than 1 percent winds of force 8 Beaufort (34 knots) or more. Not more than one tropical storm in 10 years in an area of 5° square in any 1 separate calendar month.(b) In certain special areas, for practical reasons, some degree of relaxation has been found acceptable.(c) A chart is attached to the International Convention on Load Lines, 1966, which illustrates the zones and areas defined in this Convention and in this subpart.CGFR 68-60, 33 FR 10068, July 12, 1968, as amended by CGFR 68-126, 34 FR 9016, June 5, 1969