Cable Laying and Burying

Cable Laying and Burying#

This guide will demonstrate the use of a combined cable laying and burying vessel compared to using separate cable laying and burying vessels. Here we will focus on the array cabling, but the same logic applies to the export cables.

from copy import deepcopy

import pandas as pd

from ORBIT import ProjectManager

Below, we set up a base configuration using an imagined cable and sections (25 each of 1km and 2km cable sections) designed for simplicity.

base_config = {
    "site": {"distance": 20, "depth": 35},
    "array_system": {
        "system_cost": 50e6,
        "cables": {
            "ExampleCable": {
                "linear_density": 40,
                "cable_sections": [(2, 25), (1, 25)]
            }
        }
    },
    "install_phases": ["ArrayCableInstallation"]
}

Single Cable Laying and Burying Process#

Now we can add a cable laying vessel that will simultaneously lay and bury cables by defining the array_cable_install_vessel. For export cables, this is the export_cable_install_vessel. We will create and run the project for later results comparison.

config_combined = deepcopy(base_config)
config_combined["array_cable_install_vessel"] = "example_cable_lay_vessel"

project_combined = ProjectManager(config_combined)
project_combined.run()

ORBIT library intialized at '/opt/hostedtoolcache/Python/3.13.13/x64/lib/python3.13/site-packages/library'

Separate Cable Laying and Burying Processes#

Using the same base configuration, we can now signal to the simulation to use a separate cable laying and burying process by defining both the array_cable_install_vessel and array_cable_bury_vessel. Note that the laying and combined vessel configuration keys are the same, so that a separate input is only required when the cable burying vessel is utilized. Similar to the above example, the export cable burying vessel is export_cable_bury_vessel.

Even though the vessel is the same, by defining both vessel keys, we indicate that the processes should be separated.

config_separate = deepcopy(base_config)
config_separate["array_cable_install_vessel"] = "example_cable_lay_vessel"
config_separate["array_cable_bury_vessel"] = "example_cable_lay_vessel"

project_separate = ProjectManager(config_separate)
project_separate.run()

Including a Trenching Vessel#

A third option is to also define a cable trenching vessel that digs out the trench for the cable to lie in prior to the cable laying. This is often required for rocky soil types. Similar to the separate process, we simply define the trenching vessel to activate the separated process using the array_cable_trench_vessel key or export_cable_trench_vessel for export cables.

config_separate_with_trench = deepcopy(base_config)
config_separate_with_trench["array_cable_install_vessel"] = "example_cable_lay_vessel"
config_separate_with_trench["array_cable_bury_vessel"] = "example_cable_lay_vessel"
config_separate_with_trench["array_cable_trench_vessel"] = "example_cable_lay_vessel"

# Run
project_separate_with_trench = ProjectManager(config_separate_with_trench)
project_separate_with_trench.run()

Viewing the results#

Below we show the combined process for laying and burying the first cable. Note the "action" column contains the "Lay/Bury" action to indicate the combined process.

df_combined = pd.DataFrame(project_combined.actions)
df_combined.iloc[3:12]

	cost_multiplier	agent	action	duration	cost	level	time	phase	phase_name	max_waveheight	max_windspeed	transit_speed
3	NaN	Array Cable Installation Vessel	Position Onsite	2.0	20097.583333	ACTION	9.73913	ArrayCableInstallation	NaN	NaN	NaN	NaN
4	NaN	Array Cable Installation Vessel	Prepare Cable	1.0	10048.791667	ACTION	10.73913	ArrayCableInstallation	ArrayCableInstallation	NaN	NaN	NaN
5	NaN	Array Cable Installation Vessel	Pull In Cable	5.5	55268.354167	ACTION	16.23913	ArrayCableInstallation	ArrayCableInstallation	NaN	NaN	NaN
6	NaN	Array Cable Installation Vessel	Terminate Cable	5.5	55268.354167	ACTION	21.73913	ArrayCableInstallation	ArrayCableInstallation	NaN	NaN	NaN
7	NaN	Array Cable Installation Vessel	Lower Cable	1.0	10048.791667	ACTION	22.73913	ArrayCableInstallation	ArrayCableInstallation	NaN	NaN	NaN
8	NaN	Array Cable Installation Vessel	Lay/Bury Cable	32.0	321561.333333	ACTION	54.73913	ArrayCableInstallation	ArrayCableInstallation	2.0	25.0	11.5
9	NaN	Array Cable Installation Vessel	Prepare Cable	1.0	10048.791667	ACTION	55.73913	ArrayCableInstallation	ArrayCableInstallation	NaN	NaN	NaN
10	NaN	Array Cable Installation Vessel	Pull In Cable	5.5	55268.354167	ACTION	61.23913	ArrayCableInstallation	ArrayCableInstallation	NaN	NaN	NaN
11	NaN	Array Cable Installation Vessel	Terminate Cable	5.5	55268.354167	ACTION	66.73913	ArrayCableInstallation	ArrayCableInstallation	NaN	NaN	NaN

Now, we demonstrate the separate process by combining the separate laying and burying steps taken for the first cable. Note that we have to concatenate two separate sections of the actions log to highlight this process. For each process the vessel has to "Position Onsite", then go on with the separate logic. For the burying process, this is much simpler than the initial laying and cable connection.

df_separate = pd.DataFrame(project_separate.actions)
pd.concat((df_separate.iloc[4:13], df_separate.iloc[455:457]))

	cost_multiplier	agent	action	duration	cost	level	time	phase	phase_name	max_waveheight	max_windspeed	transit_speed
4	NaN	Array Cable Installation Vessel	Position Onsite	2.000	20097.583333	ACTION	9.739130	ArrayCableInstallation	NaN	NaN	NaN	NaN
5	NaN	Array Cable Installation Vessel	Prepare Cable	1.000	10048.791667	ACTION	10.739130	ArrayCableInstallation	ArrayCableInstallation	NaN	NaN	NaN
6	NaN	Array Cable Installation Vessel	Pull In Cable	5.500	55268.354167	ACTION	16.239130	ArrayCableInstallation	ArrayCableInstallation	NaN	NaN	NaN
7	NaN	Array Cable Installation Vessel	Terminate Cable	5.500	55268.354167	ACTION	21.739130	ArrayCableInstallation	ArrayCableInstallation	NaN	NaN	NaN
8	NaN	Array Cable Installation Vessel	Lower Cable	1.000	10048.791667	ACTION	22.739130	ArrayCableInstallation	ArrayCableInstallation	NaN	NaN	NaN
9	NaN	Array Cable Installation Vessel	Lay Cable	5.000	50243.958333	ACTION	27.739130	ArrayCableInstallation	ArrayCableInstallation	2.0	25.0	11.5
10	NaN	Array Cable Installation Vessel	Prepare Cable	1.000	10048.791667	ACTION	28.739130	ArrayCableInstallation	ArrayCableInstallation	NaN	NaN	NaN
11	NaN	Array Cable Installation Vessel	Pull In Cable	5.500	55268.354167	ACTION	34.239130	ArrayCableInstallation	ArrayCableInstallation	NaN	NaN	NaN
12	NaN	Array Cable Installation Vessel	Terminate Cable	5.500	55268.354167	ACTION	39.739130	ArrayCableInstallation	ArrayCableInstallation	NaN	NaN	NaN
455	NaN	Array Cable Burial Vessel	Position Onsite	2.000	20097.583333	ACTION	1548.978261	ArrayCableInstallation	NaN	NaN	NaN	NaN
456	NaN	Array Cable Burial Vessel	Bury Cable	4.825	48485.419792	ACTION	1553.803261	ArrayCableInstallation	ArrayCableInstallation	2.0	25.0	11.5

Similar to the above, when we add trenching as a separate step, we have three discrete stages to combine to demonstrate the trenching, laying, and burying for the first cable.

df_separate_with_trench = pd.DataFrame(project_separate_with_trench.actions)
pd.concat((
    df_separate_with_trench.iloc[4:6],
    df_separate_with_trench.iloc[107:116],
    df_separate_with_trench.iloc[558:560],
))

	cost_multiplier	agent	action	duration	cost	level	time	phase	phase_name	max_waveheight	max_windspeed	transit_speed
4	NaN	Array Cable Trench Vessel	Position Onsite	2.000	20097.583333	ACTION	3.739130	ArrayCableInstallation	NaN	NaN	NaN	NaN
5	NaN	Array Cable Trench Vessel	Dig Trench	19.300	193941.679167	ACTION	23.039130	ArrayCableInstallation	ArrayCableInstallation	2.0	25.0	11.5
107	NaN	Array Cable Installation Vessel	Position Onsite	2.000	20097.583333	ACTION	828.217391	ArrayCableInstallation	NaN	NaN	NaN	NaN
108	NaN	Array Cable Installation Vessel	Prepare Cable	1.000	10048.791667	ACTION	829.217391	ArrayCableInstallation	ArrayCableInstallation	NaN	NaN	NaN
109	NaN	Array Cable Installation Vessel	Pull In Cable	5.500	55268.354167	ACTION	834.717391	ArrayCableInstallation	ArrayCableInstallation	NaN	NaN	NaN
110	NaN	Array Cable Installation Vessel	Terminate Cable	5.500	55268.354167	ACTION	840.217391	ArrayCableInstallation	ArrayCableInstallation	NaN	NaN	NaN
111	NaN	Array Cable Installation Vessel	Lower Cable	1.000	10048.791667	ACTION	841.217391	ArrayCableInstallation	ArrayCableInstallation	NaN	NaN	NaN
112	NaN	Array Cable Installation Vessel	Lay Cable	5.000	50243.958333	ACTION	846.217391	ArrayCableInstallation	ArrayCableInstallation	2.0	25.0	11.5
113	NaN	Array Cable Installation Vessel	Prepare Cable	1.000	10048.791667	ACTION	847.217391	ArrayCableInstallation	ArrayCableInstallation	NaN	NaN	NaN
114	NaN	Array Cable Installation Vessel	Pull In Cable	5.500	55268.354167	ACTION	852.717391	ArrayCableInstallation	ArrayCableInstallation	NaN	NaN	NaN
115	NaN	Array Cable Installation Vessel	Terminate Cable	5.500	55268.354167	ACTION	858.217391	ArrayCableInstallation	ArrayCableInstallation	NaN	NaN	NaN
558	NaN	Array Cable Burial Vessel	Position Onsite	2.000	20097.583333	ACTION	2367.456522	ArrayCableInstallation	NaN	NaN	NaN	NaN
559	NaN	Array Cable Burial Vessel	Bury Cable	4.825	48485.419792	ACTION	2372.281522	ArrayCableInstallation	ArrayCableInstallation	2.0	25.0	11.5