diff --git a/src/models/IdentifiedVesselShippingMethod.ts b/src/models/IdentifiedVesselShippingMethod.ts
index f51825d9..e800c8f9 100644
--- a/src/models/IdentifiedVesselShippingMethod.ts
+++ b/src/models/IdentifiedVesselShippingMethod.ts
@@ -12,7 +12,6 @@
 
 import type { IdentifiedVesselByIMOShippingMethod } from './IdentifiedVesselByIMOShippingMethod.js'
 import type { IdentifiedVesselByNameShippingMethod } from './IdentifiedVesselByNameShippingMethod.js'
-import type { Timestamp } from './Timestamp.js'
 
 /**
  * This method uses either the vessel's IMO number or the vessel name in order to select an emission factor, falling back to trade lane emissions factors if provided.
@@ -26,26 +25,17 @@ export type IdentifiedVesselShippingMethod = (
 ) & {
     vesselTracking?: {
         /**
-         * The timestamp of the departure from the source port.
-         *
-         * The more precise the better. Rule of thumb: you can be half a day off
-         * and a vessel should still be tracked correctly unless the transport is
-         * significantly shorter than half a day.
-         *
+         * The date of the departure from the source port.
          */
-        departureAt: Timestamp
+        departureOn: string
         /**
-         * The timestamp of the arrival to the destination port.
-         *
-         * The more precise the better. Rule of thumb: you can be half a day off
-         * and a vessel should still be tracked correctly unless the transport is
-         * significantly shorter than half a day.
+         * The date of the arrival to the destination port.
          *
          * We can only perform vessel tracking for shipments that finished more than
          * 24 hours ago.
          *
          */
-        arrivalAt: Timestamp
+        arrivalOn: string
         /**
          * The vessel's MMSI number at the time of arrival to the destination port.
          *