BMT Nigel Gee Ltd

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26 Νοε 2013 (πριν από 4 χρόνια και 7 μήνες)

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BMT Nigel Gee Ltd

The Transport and Installation
of Concrete Wind Foundations

European Offshore Wind 2009,

Mark Willbourn

Marketing Director

BMT Nigel Gee

Specialised in Naval Architecture and Marine Engineering Design Consultancy

part of
BMT Group

Particular expertise in “specialised vessels”

high speed, low wash and vessels with
excellent seakeeping characteristics

Experience in innovative new designs

80m high speed catamaran for US Navy and
patented 220m Pentamaran hull form

>150 vessels built to BMT NG designs

up to 220 LOA

BMT can provide not only design consultancy, structural and seakeeping analysis, etc.
but also full construction detailed design packages for operators and shipbuilders and
ship repair yards worldwide

Study Background

Gifford approached BMT NG to assist in Concrete Foundations study following earlier
feasibility study on suitability for wind farm foundations.

BMT NG’s specific task was to provide innovative but workable solutions to task of
moving large foundations to wind farm sites.

Study work included review of:

Structural requirements for “vessel”

Stability assessments

Latching mechanism

Towing requirements

Seakeeping assessments

Logistics analysis

Study Objectives

To provide an integrated systems approach to the tasks:

Coordinate design and construction of foundation and installation methodology for
efficient production

Use conventional concrete construction technology onshore

Maximise operational weather window for offshore transit and installation

Minimise reliance on expensive offshore heavy lift equipment

Use relatively simple barge concept for transport and installation

Concrete Foundation Design

stressed concrete

Slipformed stem

Reduced stem diameter at sea
bed level

Onshore Construction Site

Offices /


Load Out


Launch of Foundation

Vertical Launch

TIB Connected Over Foundation

Base Unit


Vertical Launch

TIB Features, for 3600 Te Foundation

LOA : 34 m

Beam : 32 m

Minimum Draft : 6.2 m

Operating Draft : 9.0 m

Required Water Depth
with Foundation

Unit : 11.3 m

TIB Features

Dumb barge, power only for
ballast and latching systems

Unmanned barge for normal

Simple for remote operation

High lift and transport capacity

Relatively fast system

TIB Under Tow

Maximum Hs = 3.0m

Operating Context

Seakeeping Analysis

Undertaken using VERES programme in
house by BMT

Operating criteria based on forces and motion limits that foundation could reasonably
expect to withstand and safety margins

Motion criteria for placement of foundation on sea bed are significantly more
restrictive then for transit :

Impact force on sea bed

Risk of foundation bouncing on sea bed

Risk of distortion of prepare bed

Transit criteria

no significant restrictions up to 3m significant wave height

Placement criteria

limited to 1.25m significant wave height, depending on water

TIB and Foundation Placed on Sea Bed

TIB ballast tanks flooded under
control to place Base Unit onto sea

Maximum significant wave height
Hs = 1.2m

TIB Disconnected

TIB disconnects from Base Unit

TIB deballasted with compressed
air and towed off

Manoeuvring Simulations

Not yet completed but BMT has PC Rembrandt to
undertake bespoke simulations to enable operations
and tow masters to:

Establish safe operating limits

Investigate tow and handling strategies

Assess risks for tows

Assess marine issues for installation and de

Assess mooring arrangements


Adaptation of existing technologies can provide low cost solution to transport and
installation of concrete foundations

Seakeeping analysis has determined that transport is feasible in up to 3m significant
wave height

Installation is possible in up to 1.25m significant wave height, depending on water depth

Use of TIB concept could enable installation operations in wider weather windows

As foundations get larger, operating window extends

Thank You