Siem Moxie

Installation Support Vessel (ISV) / Service Operation Vessel (SOV). Transports work crews to the platforms and foundations to prepare for submarine cable pull-in and terminations. Can support the erection and maintenance of wind turbines which are typically installed once the submarine cable installations are completed

Vessel type




Built by




Owned by

Siem Offshore

Designed by

Ulstein Design & Solutions AS

Ordered by

Siem Offshore

Operated by

Siem Offshore Contractors

Principal dimensions

74 m
17 m
Dead weight:
2,835 tonnes
Draught (max):
6.4 m
Speed (max):
9.1 kn
60 POB
Deck area:
200 sqm

Note: Subject to selected variant configuration


Offshore Support Units (OSU):
Generators, pull-in winches, tools and equipment for personnel life support on the turbine foundations.
Motion-compensated gangway:
"Walk to Work” (W2W)
Gangway for safe transfer personnel to the foundations :
Hs up to 3.0 m
Knuckle boom crane:
3-Axis motion-compensated
Voith Schneider Propellers:
2 sets

Featured solutions

Ship history

Designed by ULSTEIN, 'Siem Moxie' is the very first Service Operation Vessel developed and purpose-built for the offshore wind sector. 
Built at Fjellstrand Verft for Siem Offshore, the 'Siem Moxie' was named in Hamburg on 10 April 2014. E.ON took patronage of the ship after delivery. 

“We chose the Siem Moxie because it will make our installation operations extremely safe and efficient,” Sven Utermöhlen, Head of International Offshore business at E.ON,  explained.
“In addition it will help make the construction of offshore wind farms more cost-effective, thereby helping this technology move closer to market maturity.” 

The Siem Moxie was firstly deployed on E.ON’s Amrumbank West offshore wind farm project north of Helgoland by Siem Offshore Contractors for the installation of the inner array grid submarine cable system. Working in installation support, the vessel is also characterized as an ISV vessel. 

Watch film of the 'Siem Moxie' at work.

Offshore Renewables Award

The Siem Moxie was awarded the “Offshore Renewables Awards 2014”. It is the very first X-BOW support vessel which features two sets of Voith Schneider Propellers. Its design drew on a wealth of experience within the offshore business. The Siem Moxie’s low fuel consumption makes it particularly environmentally friendly. The vessel’s key features are a 3D motion-compensated knuckle boom crane and an active motion compensated personnel transfer gangway, permitting the safe transfer of work crews. Thanks to the ship’s active roll stabilization capabilities, offshore works can continue even in challenging sea and wind conditions. 

2016: Nordsee One - 'Siem Duo'
Working as part of a 'Siem Duo' in cable installation works on the Nordsee One Offshore Wind Farm (OWF) in the German Bight of the North Sea. The 'Siem Duo' is consisting of the Cable Lay Vessel (CLV) Siem Aimery and the Installation Support Vessel (ISV) Siem Moxie. The Siem Moxie is assisting the CLV for the submarine cable pull-in, termination and testing activities. The vessel's active motion-compensated “Walk to Work” (W2W) gangway is used to safely transfer personnel to and from the individual foundations in significant wave heights of up to 3 m. In September, three weeks ahead of schedule, the inter-array cables for the wind farm had been installed, as well as the foundations and the offshore substation for the 54 wind turbines. 

2016/17: Veja Mate - 'Siem Duo'
Siem Offshore Contractors was also awarded the engineering, procurement, installation and commissioning (EPIC) contract for the IAG cable system of the Veja Mate Offshore Wind Farm. The 67 wind turbine generators of the project are located 115km north of the German coastline within the German Bight sector of the North Sea in water depths of up to 40 metres.

Starting on 1 October 2016, the 'Siem Duo' started the installation of the submarine composite cables on the Offshore Wind Farm, and on 6. February 2017, Siem Offshore Contractors (SOC) announced that all 73 inner array grid cables of the Offshore Wind Farm had been installed and trenched 10 weeks ahead of schedule; "The Siem Duo demonstrated its advanced weather operability during the harsh winter season, whereby both the operations of the gangway on the Siem Moxie as well as post-lay trenching by the Siem Aimery were undertaken in significant wave heights of up to 3 m." Mr. Regis Rougier, Managing Director of Siem Offshore Contractors stated: “It is a pleasure to confirm the successful completion of another project ahead of schedule, our third project utilising the “Siem Duo”."

The Siem Moxie assisted with the cable pull-in, termination and testing activities deploying SOC’s dedicated offshore support units (OSU) equipped with generators, pull-in winches, tools and equipment for personnel life support at the individual offshore work sites. The OSUs were transferred using the Siem Moxie’s 3D motion-compensated crane, while the active motion-compensated “Walk to Work” gangway was used to facilitate more than 10,000 personnel transfers to and from the individual foundations and offshore substation. The cable termination and testing works continue and are expected to be completed within a couple of weeks, also ahead of schedule.

Please contact us for more information