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Deconstructing Subsea Cable Installation: LIVINGSTONE at South Fork Wind

  • Jan 24
  • 3 min read
LIVING STONE (DEME)
LIVING STONE (DEME)

We tracked DEME’s cable lay vessel LIVINGSTONE to break down the installation campaign of both export cable (EC) and inter-array cable (IAC) scopes for Ørsted’s South Fork Wind project. Our study reveals the major cost drivers of subsea cable installation for an early U.S. Offshore Wind project.


Project Overview

Project: South Fork Wind (Ørsted)Cable Installation Vessel: LIVINGSTONE (DEME)Shore Landing: Wainscott Beach, Long Island

No. of Export Cables: 1

No. of Offshore Sub-Stations (OSS): 1Export Cable Distance: 66 milesInter-Array Cable Distance: 21 miles

Export Cable Characteristics

  • Single export cable

  • Installed in two segments

  • One mid-corridor jointing operation

 

Logistics Profile

  • 5x port calls to Providence, RI (Prov Port), totaling 16 days

  • 2x load-out calls to Nexans Goose Creek, SC:

    • First visit: initial export cable segment, 14 days

    • Second visit: second export cable segment, 13 days

  • Cable lay and post-lay trench & burial scopes were both performed by LIVINGSTONE

  • The inter-array cable was delivered to Prov Port via transatlantic heavy lift vessel and was subsequently loaded onto LIVINGSTONE

 

Campaign Duration Breakdown

Total tracked campaign time: 3,532 hours (147.2 days)


Time Allocation by Scope

Scope

Days

% of Total

Transit

8.5

6%

Idle

31.4

21%

Pre-Lay Survey

2.6

2%

EC Lay 1

4.7

3%

EC Shore Pull-In

1.5

1%

EC Burial 1

11.9

8%

Jointing

9.0

6%

EC Lay 2

4.9

3%

EC Burial 2

16.4

11%

Mattress Install

3.5

2%

EC Post-Lay Survey

3.5

2%

IAC 1

4.4

3%

IAC 2

1.0

1%

IAC 3

35.5

24%

Key Observations


1. Idle Time Was Material

Idle time accounted for 31.4 days (21%) of total campaign duration.


For capital-intensive assets such as DP cable lay vessels, this represents meaningful cost exposure. Idle time may reflect:

  • Weather constraints

  • Port scheduling

  • Equipment readiness

  • Regulatory or inspection delays

  • Sequencing between export and array scopes


Understanding the drivers behind idle time is essential for future cost optimization.


2. Burial Was the Dominant Export Cable Activity

Export cable burial alone consumed:

  • Burial 1: 11.9 days

  • Burial 2: 16.4 days

  • Total burial: 28.3 days


That exceeds total export lay time (9.6 days combined for Lay 1 and Lay 2).


This reinforces that burial — not lay — is typically the rate-determining step in export cable installation.


3. Jointing Was Non-Trivial

The single mid-corridor jointing operation required 9 days, representing 6% of total campaign duration.

Even a single joint introduces material schedule exposure.


4. Inter-Array Scope Was Concentrated in One Extended Campaign

The third IAC campaign (IAC 3) alone consumed 35.5 days (24% of total campaign time).


The distribution suggests:

  • A prolonged final array push

  • Possible weather sensitivity

  • Or concentration of remaining strings


Productivity


Export Cable Work (Excluding Survey)

  • 48.4 days total

  • 0.73 days per mile


Inter-Array Cable Work (Excluding Survey)

  • 40.8 days total

  • 1.94 days per mile


Inter-array installation required nearly 3x more time per mile than export cable installation.


This differential likely reflects:

  • Increased complexity of multiple short strings

  • Repeated touchdown and positioning

  • Array routing geometry

  • Smaller campaign batches


Export cable installation benefits from longer continuous lay runs, while inter-array work introduces higher operational friction per mile.


Our Takeaways


Several themes emerge from this vessel-level analysis:

  • Idle and non-lay activities consume a significant share of campaign duration.

  • Burial — not lay speed — governs export cable schedule risk.

  • Jointing events introduce discrete schedule blocks that must be modeled explicitly.

  • Inter-array installation is structurally less efficient per mile than export cable installation.


For developers and financiers, this has implications for:

  • Contingency modeling

  • Vessel day rate exposure

  • Weather window risk

  • Supply chain synchronization

  • Port logistics planning


Breaking down vessel behavior at the activity level reveals what actually governs schedule and cost performance. For developers and EPC contractors, this visibility enables more deliberate allocation of installation scopes, improved utilization of high-value assets, and better management of execution and risk factors in U.S. Offshore Wind campaigns.


 


 
 
 

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