JP 3-50 National Search and Rescue Manual Vol I - US Navy

approximately 20 percent faster than rafts without.
c. Rafts with ballast pockets have leeway speeds
approximately 20 percent slower than rafts without.
d. Rafts with canopies and a deep ballast system have
uncertain leeway speed. Speeds approximately the same as for
rafts with drogue may be assumed. The minimum leeway speed is
zero for winds of 5 knots or less, and 0.1 knot for winds
greater than 5 knots. For a deep ballast raft where the
canopy does not deploy, the leeway speed falls to between 3
percent of the wind speed and zero.
2. Leeway direction is subject to large variations. It is
usually assumed to be downwind, with diver gence compensated
for by extending the search areas to the right and left of
downwind.
a. The maximum angles off downwind are 45 degrees for
craft with moderate to deep draft, 60 degrees for craft with a
relatively shallow draft, and 35 degrees for rubber rafts.
b. Circular rafts with under vater portions symmetrical
about a vertical axis through the center of the raft are
considered a special category with a maximum leeway angle
about 15 degrees either side of downwind. Circular rafts with
a deep ballast system fall into this category, while rafts
with asymmetrical ballast pockets do not. This category
should not be assumed if doubt about raft type exists.
Figure 5-5. Leeway Speed
5-7