IALA

Ship waypoints (WP) and/or route plan report

Number of bits Description
NWP 4 Number of next waypoints available (1-14);  0 = no next waypoint available = default; 15 = not used
WP i.Lon 28 Longitude of next waypoint i in 1/10 000 min (±180°, East = positive, West = negative). Field required if and as often as 1 ≤ i ≤ NWP, i = 1, 2, 3, …, 14;  field not required if NWP = 0
WP i.Lat 27 Latitude of next waypoint i in 1/10 000 min (±90°, North = positive, South = negative). Field required if and as often as 1 ≤ i ≤ NWP, i = 1, 2, 3, …, 14; field not required if NWP = 0
Route specified by textual description 120 Description of the route information in textual form, e.g. —West channel“; maximum 20 characters using 6-bit ASCII; @@@@@@@@@@@@@@@@@@@@ = not available (field must not be omitted)
Spare NWP Bits Spare. Not used. Should be set to zero
0, 8 4
1, 9 5
2, 10 6
3, 11 7
4, 12 0
5, 13 1
6, 14 2
7 3
Number of bits  128-896  The number of bits of the IFM 17 may be calculated as follows: 124 + (NWP × 55) + spare 

The number of slots used for this message depends on the number of next waypoints transmitted as
follows:

 

 Number of next waypoints   transmitted 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
 Number of slots used for this   message 2 2 2 3 3 3 3 4 4 4 4 5 5 5 5