ACMA has applied its 45 years of experience in the offshore and marine industries to the offshore wind industry regarding the transport of turbine components, lifting and installation issues, and utilizing advanced analyses to determine design forces.
ACMA has designed multi-level rack systems for the transport of large numbers of wind turbine blades. The system was designed to be placed on the deck of an ocean-going barge. The system has similarities to modern-day container service in that individual securing was avoided to reduce loading and unloading time while ensuring the system was sufficiently robust to withstand the rigors of ocean crossings.
Wind turbine towers are typically transported as deck cargo on ships stacked several units high. Relying on our experience from the offshore transportation industry, where ACMA has successfully secured a wide array of cargos, we have developed securing systems for towers too. While these components are definitely different, they still require the same consideration of accelerations and available geometry to develop an effective tie-down and securing arrangement. ACMA has performed tie-down analyses to ensure the towers remain on deck even in the roughest of sea conditions. ACMA has also provided onboard verification services to ensure the tie-downs were affected in accordance with our design.
Transport of components to the offshore site must occur on US Flagged vessels. The current environment necessitates the utilization of existing assets that have been re-purposed from the offshore or other industries. The transfer of these components to an installation vessel is not unlike transferring a modern-day large BOP. The key difference is the process must occur multiple times in a relatively short time span. Concise prediction of relative motions between the transport vessel and the crane on the installation vessel is critical to successfully achieving this transfer on a repeatable basis. Thorough knowledge of crane operations, capabilities and limitations is required. Eventually, new special-purpose vessels will be designed to meet this need most efficiently.
The design of specialty vessels to meet the specific needs of the offshore wind industry is required to achieve the needed efficiency over the long term. This includes transporting service personnel offshore to these sights in a physical state whereby they are ready to go to work immediately. Vessels designed to provide a low incidence of seasickness over a 4-6 hour transit voyage are required to meet this challenge. ACMA designed and oversaw the building of a 30 knot 250 passenger SWATH crewboat for the offshore industry, specifically for operation in the Campos Basin offshore Brazil. The wind industry has similar needs, but one key difference is that only a few people are required at each turbine. This transport vessel must stop at a turbine, transfer 6-8 technicians with tools and spare parts and then move to the next turbine. Therefore, low motions at zero speed are extremely important as well as during the relatively high-speed transit. The SWATH hull form can provide this seakeeping advantage coupled with the large deck area for the relatively low density “cargo”, i.e., the 40-60 turbine technicians and their required material.