a number of operators have also increased ‘passenger’ carrying capacity to twenty-four plus persons by utilising the new IMO definition of ‘industrial personnel’. Both the UK and Germany have a High Speed, Offshore Service Craft Code1
(HS-OSC), under which a Cardinal P Photo courtesy of Offshore Turbine Services
Scale and variety of the CTV market
There are currently more than 400 CTVs working in the northern European wind farm industry, the vast majority are under 24 metres load line length and normally carry up to twelve passengers. The most popular hull material is aluminium alloy, although there are a significant number of GRP vessels as well. In addition to the most common, catamaran design, some operators have chosen to select monohulls, trimarans or SWATHs.
The search for the ideal propulsor that can provide high speed transits, excellent manoeuvrability, fuel economy and bollard pull has led designers to experiment with water jet, controllable pitch and fixed pitch propeller systems; usually powered by two, but sometimes four, high speed diesels. As CTVs have grown in size the engines have naturally had to follow suit with some vessels using V12 engines with triple turbochargers producing over 1400 kW. Needless to say, engine control and management systems have become more complex and the vessels often use bridge systems similar to those found on fast ferries or superyachts.
The primary purpose of the CTV is to transfer technicians from shore, or a hotel ship, to the wind farm and
safely transfer these technicians by ‘pushing on’ to the boat landing on the bright yellow transition piece (TP) at the base of the wind turbine tower. As this activity is fundamental to the safe and successful operation of a wind farm it is the area of most interest to the vessel operator and charterer and bow fenders and access systems represent a significant IP and capital investment to the vessel owner.
In addition to technicians, most CTVs are also used to carry cargo. Many CTVs are fitted with a knuckle boom crane on the foredeck to facilitate self-loading at the quayside and this requires a substantial deck structure and hydraulic system. As the CTV cargo may include diesel fuel for temporary power generation on the transition piece, most vessels have fuel transfer pumps for pumping fuel up to the TP platform from the vessel’s own fuel tanks.
The survey regime
As with all commercial vessels, CTVs must first meet the primary Flag State requirements. As most CTVs are under 24-metres load line length, UK vessels are normally built and operate under the Workboat Code, but many vessel operators have also chosen to build and maintain vessels to class under the Special Service Craft or High Speed & Light Craft rules. More recently,
40 | The Report • September 2017 • Issue 81
suitably equipped workboat under 24-metres may carry up to thirty- six industrial personnel. The new HS-OSC Code is an extension of the Special Purpose Ships Code2
and
was written with the wind farm industry firmly in mind.
Section 30 of the new, UK Workboat Code makes specific reference to the need for a Safety Management System, “which complies with the principles of the International Safety Management (ISM) Code”. Most CTV operators have gone one step further and are externally audited and accredited by either the MCA or a Classification Society. For a surveyor to properly complete the SCV2 and/or CMID a good understanding of the Company’s safety management ethos is important. This will include the surveyor reviewing the crew certification and competency and auditing recent drills.
To permit workboats and CTVs to carry packaged dangerous goods such as propane, petrol, resin and paint, the vessels are required to have a Dangerous Goods Document of Compliance (DG DoC). For UK flagged vessels, dangerous goods and cargo are covered by the Workboat Code and MCA Surveyor Advice Note 75. The diesel fuel transfer system may be inspected by a Certifying Authority (CA) surveyor, however, the DG DoC may only be issued following an inspection by an MCA surveyor. The inspection and acceptance of the fuel transfer system is normally attached as an addendum to the SCV2, whereas the DG DoC is a separate document and normally lasts five years.
1 Code for High Speed Offshore Craft (HS-OSC) (of less than 500GT carrying up to 60 persons)
2
MGN 515 (M) Special Purpose Ships (SPS) Code: Application to Offshore Vessels
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