j-atkins · Oct 20, 2026 · Sep 23, 2026 · Sep 25, 2026 · Sep 25, 2026 · Sep 25, 2026
diff --git a/docs/user-guide/assignments/Research_proposal_intro.ipynb b/docs/user-guide/assignments/Research_proposal_intro.ipynb
@@ -45,11 +45,11 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "### Underway Data \n",
+    "### Underway Temperature and Salinity measurements\n",
     "\n",
     "Underway data collection, also known as underway sampling, refers to the process of collecting oceanographic and environmental data while a research vessel is in motion. This method allows scientists to continuously gather data on various parameters such as sea surface temperature and salinity. The water inlet is located on the hull of the ship at approximately 2 meters under the surface.\n",
     "\n",
-    "You can collect underway data during your entire cruise or on specific transects and may assume it doesn’t take any time to start or stop taking measurements."
+    "You can collect underway data during your entire cruise. These measurements can be taken continuously without interrupting the ship's speed. It doesn’t take any time to start or stop the ship for these measurements."
    ]
   },
   {
@@ -60,7 +60,9 @@
     "\n",
     "An Acoustic Doppler Current Profiler (ADCP) is an instrument used to measure the speed and direction of ocean currents at various depths. It operates based on the principle of Doppler shift, where sound waves emitted by the instrument are reflected off moving particles in the water, such as plankton or sediment, and the frequency shift of the returning waves is used to calculate the velocity of the water.\n",
     "\n",
-    "You can deploy the ADCP on transects and choose between a shallow profiler capable of providing information to a depth of 150 m every 4 meters (the 300kHz seaSeven), or a long-range profiler capable of providing about 1000m of range every 24 meters (the 38kHz Ocean Observer). You can collect ADCP data during your entire cruise or on specific transects and may assume it doesn’t take any time to start or end ADCP measurements.\n",
+    "You can choose between a shallow profiler capable of providing information to a depth of 150 m every 4 meters (the 300kHz seaSeven), or a long-range profiler capable of providing about 1000m of range every 24 meters (the 38kHz Ocean Observer). \n",
+    "\n",
+    "You can collect ADCP data during your entire cruise. These measurements can be taken continuously without interrupting the ship's speed. It doesn’t take any time to start or stop the ship for these measurements.\n",
     "\n",
     "<iframe width=\"560\" height=\"315\" src=\"https://www.youtube.com/embed/mDyoZagght8?si=VCXfJC7knpQpR2p9&amp;start=37\" title=\"YouTube video player\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen></iframe>"
    ]
@@ -73,7 +75,7 @@
     "\n",
     "An eXpendable BathyThermograph (XBT) is a probe that is dropped from a ship and measures the temperature as it falls through the water. The probe is designed to fall at a known rate, so that the depth of the temperature profile can be inferred from the time since it enters the water.\n",
     "\n",
-    "You may assume it doesn’t take any time to deploy XBTs.\n",
+    "You may assume it doesn’t take any time to deploy XBTs. They can be deployed while the ship is moving at full speed, so there is no time cost for slowing down or speeding up the ship.\n",
     "\n",
     "<iframe width=\"560\" height=\"315\" src=\"https://www.youtube.com/embed/gAvxRYCnSXY?si=owx8YEPS-0FBIGSf\" title=\"YouTube video player\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen></iframe>"
    ]
@@ -87,15 +89,12 @@
     "\n",
     "A Conductivity, Temperature, and Depth (CTD) sensor is an instrument used to measure the physical (or biogeochemical) properties of seawater in oceanographic and environmental research. It typically consists of sensors for conductivity (used to derive salinity), temperature, and pressure (used to derive depth). CTDs can also be equipped with additional sensors to measure biogeochemical parameters such as dissolved oxygen, chlorophyll, and nutrients. \n",
     "\n",
-    "Throughout a CTD deployment, the research vessels needs to stay in the same location. To calculate the time needed for a CTD deployment, take the following information into account:\n",
-    "\n",
-    "<!-- TODO: this should be updated when the time is calculated as depth dependent (see [#249](https://github.com/Parcels-code/virtualship/issues/249)) -->\n",
-    "* Add time to lower the vessels speed to zero and set the vessel to the appropriate direction against swell, current, wind, etc = 15 minutes \n",
-    "* Add time to deploy the CTD, and to recover = 10 minutes (2*5 min) \n",
-    "* Add time to raise the CTD down and up, usually at 1 m/s (winch capacity). We make an assumption in VirtualShip that the average CTD downcast/upcast takes 15 minutes.\n",
-    "* Add time to speed the ship back up again and set course to the next waypoint = 10 minutes\n",
+    "Throughout a CTD deployment, the research vessels needs to stay in the same location. To calculate the time needed for a CTD deployment at a given waypoint, take the following information into account:\n",
     "\n",
-    "In total, therefore, you can expect a CTD deployment to take approximately 50 minutes.\n",
+    "* The ship needs to slow down to a stop, which takes 15 minutes (default in VirtualShip)\n",
+    "* The CTD is lowered to the configured maximum depth or the sea floor, whichever is shallowest. The time taken therefore depends on the depth in that location and the winch speed (default is 1 m/s in VirtualShip). Remember that the time is doubled as well because the CTD needs to be brought back up.\n",
+    "    * For example, if the CTD is lowered to 1000 m at a speed of 1 m/s, it will take approximately 16.7 minutes to reach that depth, and the same amount of time to raise it back up, so in total: approx. 33.4 minutes.\n",
+    "* The ship needs to speed back up again and set course to the next waypoint, which takes another 15 minutes (default in VirtualShip).\n",
     "\n",
     "<iframe width=\"560\" height=\"315\" src=\"https://www.youtube.com/embed/7N2UsPDczTw\" title=\"YouTube video player\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture\" allowfullscreen></iframe>"
    ]
@@ -108,7 +107,7 @@
     "\n",
     "A surface drifter is an oceanographic instrument used to study surface currents and ocean circulation patterns. These devices are designed to drift passively with the surface currents while transmitting data on their position and sea surface temperature.\n",
     "\n",
-    "You should assume it takes a combined 20 minutes to both slow down and speed the ship back up, in order to safely deploy drifters from the ship. Make sure to account for this time in your planning.\n",
+    "For deployment, the ship needs to slow down to a stop, which takes 15 minutes (default in VirtualShip). You can assume the actual release takes no time but then after the deployment the ship needs to speed back up again and set course to the next waypoint, which takes another 15 minutes (default in VirtualShip).\n",
     "\n",
     "<iframe width=\"560\" height=\"315\" src=\"https://www.youtube.com/embed/3m_CxEE8Bhs?si=XdyMFAVq9RVxQdcE&amp;start=15\" title=\"YouTube video player\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen></iframe>"
    ]
@@ -123,7 +122,7 @@
     "\n",
     "The floats periodically descend to a predetermined depth, typically around 1000 meters, and then ascend to the surface, measuring temperature and salinity profiles along the way.\n",
     "\n",
-    "You should assume it takes a combined 20 minutes to both slow down and speed the ship back up, in order to safely deploy Argo floats from the ship. Make sure to account for this time in your planning.\n",
+    "For deployment, the ship needs to slow down to a stop, which takes 15 minutes (default in VirtualShip). You can assume the actual release takes no time but then after the deployment the ship needs to speed back up again and set course to the next waypoint, which takes another 15 minutes (default in VirtualShip).\n",
     "    \n",
     "<iframe width=\"560\" height=\"315\" src=\"https://www.youtube.com/embed/IgcYQML5se4?si=Y7m1kLqUl14QZfcd\" title=\"YouTube video player\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen></iframe>"
    ]

diff --git a/docs/user-guide/assignments/sail_the_ship.md b/docs/user-guide/assignments/sail_the_ship.md
@@ -92,6 +92,12 @@ The `{CruiseDataExport}.xlsx` in the command above refers to the `.xlsx` file ex
 The `--start-date` should be set to your intended departure date/time. MFP's estimated travel and station durations are then used to automatically fill in a time for each waypoint relative to this start date.
 ```
 
+```{important}
+MFP usually allows a default of **45 minutes** stationkeeping time at each station. This may be enough for your expedition, but it may not be, so expect to adjust some of your timings once you have chosen your instruments (in step 5) [below](#waypoint-datetimes)).
+
+Hint: pay particular attention to CTDs deployments in deep waters. A CTD is lowered on a winch all the way to the seabed and brought back up, so the deeper the water, the longer the ship has to sit still.
+```
+
 This will create a folder/directory called `EXPEDITION_NAME` (or what you have changed this to) with a single file: `expedition.yaml`. This file contains details on the ship and instrument configurations, as well as the expedition schedule based on the sampling site coordinates (and, if specified, ports of departure/arrival) from your MFP export. The `--from-mfp` flag indicates that the exported route will be used, and `--start-date` is required alongside it.
 
 ## 5) Expedition scheduling & ship configuration
@@ -149,7 +155,15 @@ Your Port of Departure and Port of Arrival (if set in MFP) appear as special way
 ```
 
 ```{note}
-It is important to ensure that the timings for each station are realistic. There must be enough time for the ship to travel to each site at the prescribed speed (10 knots). The expedition schedule will be automatically verified when you press _Save Changes_ in the planning tool.
+It is important to ensure that the timings for each station are realistic. There must be enough time for the ship to travel to each site at the prescribed speed (10 knots), **and** enough time to actually carry out your deployments once you arrive. The expedition schedule will be automatically verified when you press _Save Changes_ in the planning tool.
+```
+
+```{important}
+Remember that MFP's default of 45 minutes per station may not be enough once your instruments are selected. Time at a station is made up of slowing the ship down (15 minutes by default), carrying out the deployments (which depends on which instruments you deploy), and getting back up to speed again (15 minutes by default).
+
+Deployments can take place side by side, so only the slowest one matters for the total stationkeeping time at each waypoint. Drifters and Argo floats are simply released into the water and left behind, so they have no time cost apart from slowing down and speeding up the ship. A CTD is different. It takes longer because it has to be lowered and brought back up, so the ship waits for the full round trip, and a cast at a deep station can easily take longer than the MFP default. An XBT is different in the opposite way. It doesn't even need the ship to slow down, so it can be deployed while the ship is moving at full speed.
+
+**See [here](../assignments/Research_proposal_intro.ipynb) for more information on the times taken for each instrument deployment.**
 ```
 
 ### Instrument selection

diff --git a/docs/user-guide/quickstart.md b/docs/user-guide/quickstart.md
@@ -56,6 +56,11 @@ The `CruiseDataExport.xlsx` in the `virtualship init` command refers to the .xls
 The `--start-date` should be set to your intended departure date/time. MFP's estimated travel and station durations are then used to automatically fill in a time for each waypoint relative to this start date.
 ```
 
+```{important}
+
+MFP usually allows a default of **45 minutes** stationkeeping time at each station, and that default is what determines the waypoint times written into your `expedition.yaml`. That may well be enough for your expedition, but it may not be, so be prepared to adjust the times once you have chosen your instruments and come to [adjusting the waypoint datetimes](#waypoint-datetimes).
+```
+
 This will create a folder/directory called `EXPEDITION_NAME` with a single file: `expedition.yaml` containing details on the ship and instrument configurations, as well as the expedition schedule based on the sampling site coordinates (and, if specified, ports of departure/arrival) from your MFP export. The `--from-mfp` flag indicates that the exported route will be used, and `--start-date` is required alongside it.
 
 ```{note}
@@ -122,6 +127,13 @@ Your Port of Departure and Port of Arrival (if set in MFP) appear as special way
 
 ```{note}
 It is important to ensure that the timings for each station are realistic. There must be enough time for the ship to travel to each site at a realistic speed (~ 10 knots). The expedition schedule (and the ship's configuration) will be automatically verified when you press _Save Changes_ in the planning tool.
+
+Remember that MFP's default of 45 minutes per station may not be enough once your instruments are selected (see [below](#instrument-selection)). Time at a station is made up of slowing the ship down (15 minutes by default), carrying out the deployments (which depends on which instruments you deploy), and getting back up to speed again (15 minutes by default).
+
+Deployments can take place side by side, so only the slowest one matters for the total stationkeeping time at each waypoint. Drifters and Argo floats are simply released into the water and left behind, so they have no time cost apart from slowing down and speeding up the ship. A CTD is different. It takes longer because it has to be lowered and brought back up, so the ship waits for the full round trip, and a cast at a deep station can easily take longer than the MFP default. An XBT is different in the opposite way. It doesn't even need the ship to slow down, so it can be deployed while the ship is moving at full speed.
+
+**See [here](../assignments/Research_proposal_intro.ipynb) for more information on the times taken for each instrument deployment.**
+
 ```
 
 ### Instrument selection

diff --git a/docs/user-guide/tutorials/working_with_expedition_yaml.md b/docs/user-guide/tutorials/working_with_expedition_yaml.md
@@ -40,6 +40,7 @@ schedule: # <-- 1. expedition schedule section
       location:
         latitude: 45.604174
         longitude: -43.886739
+      sea_depth_meter: -4400.0
       time: 1998-03-08 03:37:00
     # Waypoint 2
     - instrument:
@@ -49,6 +50,7 @@ schedule: # <-- 1. expedition schedule section
       location:
         latitude: 48.185988
         longitude: -32.988302
+      sea_depth_meter: -3200.0
       time: 1998-03-10 03:05:00
     # Port of Arrival
     - location:
@@ -75,6 +77,8 @@ instruments_config: # <-- 2. instrument configuration section
 #
 ship_config: # <-- 3. ship configuration section
   ship_speed_knots: 10.0
+  waypoint_slowdown_time_minutes: 15.0
+  waypoint_speedup_time_minutes: 15.0
 ```
 
 ```{note}
@@ -113,9 +117,7 @@ You can do multiple `DRIFTER` deployments at the same waypoint by adding multipl
 
 - **Time (`time`)**: The scheduled time for reaching the waypoint, specifically in YYYY-MM-DD HH:MM:SS format.
 
-##### Comments
-
-You may notice comments such as `# Port of Departure`, `# Waypoint 1`, `# Waypoint 2`, etc. next to each entry in the `waypoints` list, as in the example above. These are added automatically whenever `virtualship init` or `virtualship plan` writes the file, purely to aid readability. They are not required when editing the file by hand and won't be automatically added/renumbered by doing so.
+- **Sea depth (`sea_depth_meter`)**: The estimated depth of the water column at the waypoint. This value matters because it determines how a long a deployment takes if there is a depth dependence, e.g. for a CTD that has to be lowered and raised. If you leave it as `null`, VirtualShip doesn't know how deep the water is and assumes the CTD descends all the way to its configured `max_depth_meter`. That is the slowest possible cast, so your schedule is verified against a worst case rather than an optimistic one in the simulations.
 
 #### 2. `instruments_config`
 
@@ -129,7 +131,7 @@ For most users, the most important instrument configuration setting to consider
 ctd_config:
   max_depth_meter: -2000.0
   min_depth_meter: -11.0
-  stationkeeping_time_minutes: 50.0
+  winch_speed_meter_per_second: 1.0
   sensors:
     - TEMPERATURE
     - SALINITY
@@ -158,4 +160,4 @@ This section contains setting related to the ship itself, specifically:
 
 - **Ship speed (`ship_speed_knots`)**: The speed of the ship in knots (nautical miles per hour; where 1 knot = 1.852 km/h). Note in most cases this should be left as the default value unless there is a specific reason to change it.
 
-<!-- TODO: more details on ship configuration if added in the future -->
+- **Waypoint slow-down and speed-up times (`waypoint_slowdown_time_minutes`, `waypoint_speedup_time_minutes`)**: How long the ship takes to slow to a stop before deployments begin at a waypoint, and to get back up to cruising speed afterwards, respectively. These are added once at every waypoint where you deploy instruments which require the ship to slow down.