Maritime Data Section The Maritime Data Section, or Section 2 of the code, follows the indicator 222, the first three digits in the  222Dsvs  group.  This  section  is  normally  not transmitted from land stations, since it contains course and speed of the ship, sea-surface temperature, sea and swell wave information, ice accretion information, and information on sea ice. SHIP’S  COURSE  AND  SPEED.—222D_Sv_S. The D_S is the direction of displacement of the ship from 3 hours before the report indicated using WMO code table 0700 (0 is no displacement, 1 is toward the northeast, 2 is toward the east, etc.). The v_S indicates the speed "made good" from 3 hours before the observation until the observation time (in 5-knot increments) using WMO code table 4451. For example, a ship may move in a large circle at 10 knots, ending up at report time at the same location it was 3 hours previous. The D_S would be encoded as 0 for "no net displacement," and v_S would be encoded as 0 for "no speed made good." A second ship may follow an erratic course, ending up at report time 2 1 nautical miles southeast of the position 3 hours previous. The D_S is encoded as 3 for southeast displacement, and the v_S is encoded as 2 for speed made good "6 to 10 knots" (21 nautical miles divided by 3 hours  equals  7  knots). SEA   -   SURFACE   TEMPERATURE.— 0S_sT_WT_WT_W. The code symbol  S_s  is the temperature sign for seawater, which is followed by the sea-surface temperature in tens, units, and tenths of degrees Celsius as  T_WT_WT_W. SEA WAVES.—2P_wP_wH_wH_w. The period of the sea waves, as determined by an observer, is reported as P_wP_W in tens and units of seconds. The height of the sea waves is reported in one-half meter units in H_wH_w. Convert observed height in feet to half-meter units by multiplying by 0.61 and rounding off. When decoding, half-meter  units  may  be  converted  to  feet  by multiplying by 1.64. A conversion table is available in NAVMETOCCOMINST   3144.1.   Ships   with automatic wave sensors and buoys with sensors use group 1P_waP_waH_waH_wa in place of the "2" group. The P_waP_wa  is  the  sensor-measured  sea-wave  period,  and H_waH_wa is the sensor-measured sea-wave height in half-meter  units. S W E L L W A V E S.—3d_w1d_w1d_w2d_w2, 4P_w1P_w1H_w1H_w1,   and   5P_w2P_w2H_w2H_w2,   (or   group 70H_waH_waH_wa). Two significant swell waves may be reported. Swell-Wave  Direction.—Group  3  reports  the primary swell wave direction in hundreds and tens of degrees as d_W1d_W1 and the secondary swell wave direction  as  d_W2d_W2.  When  no  swell  waves  are observed, the group is encoded as 30000, and both the 4P_W1P_W1H_W1H_W1 and 5P_W2P_W2H_W2H_W2 groups are reported as 40000 and 50000. If only one swell wave is observed,  the  dw₂dw₂  is  encoded  as  00,  and  the 5P_W2P_W2H_W2H_W2  group  is  reported  as  50000. Swell-Wave  Period  and  Height.—The primary swell-wave period and primary swell-wave height are reported  in  group  4P_W1P_W1H_W1H_W1.  The  secondary swell-wave  period  and  height  are  reported  in  group 5P_W2P_W2H_W2H_W2. The P_W1or2P_W1or2 is the swell-wave period  in  tens  and  units  of  seconds,  while  the H_W1or2HW_1or2 is the height of the swell waves in half- meter  units. Swell-Wave   Height   From   Sensors.-Ships equipped  with  automatic  wave-height-measuring equipment  report  the  swell-wave  height  by  using  group 70H_waH_waH_wa in place of groups 3, 4, and 5. The H_waH_waH_wa is the wave height in tens, units, and tenths of  meters.  Swell-wave  direction  and  period  from automatic sensors are normally not reported. ICE ACCRETION.—6I_SE_SE_SR_S.     The     ice accretion group is only included in a report when ice accretion is occurring. The I_S is the source of the ice (WMO code table 1751); the E_SE_S is the thickness of the ice, in centimeters; and the R_S is the rate of accretion (or loss) (WMO code table 3551). WET-BULB   TEMPERATURE.—8S_wT_bT_bT_b. The wet-bulb temperature group is indicated by code figure 8. The S_w is the sign and type of the wet-bulb temperature (WMO code table 3855) and T_bT_bT_b is the wet-bulb temperature in tens, units, and tenths of a degree Celsius. SEA ICE.—ICE c_iS_ib_iD_iz_i. The sea ice group is only reported when ice is observed in the sea. "ICE" is the indicator that the sea ice group follows. The c_i is the concentration or arrangement of sea ice (WMO code table 0639), S_i is the stage of development (WMO code table 3739), b_i is ice of land origin (WMO code table 0439), D_i is the true bearing of the principal ice edge (WMO code table 0739) and z_i is the ice situation and trend over the past 3 hours (WMO code table 5239). In addition to the sea ice code, any remarks considered significant by the observer may be transmitted as plain language remarks. 3-17