With many among the naval architect community opposing steel as the ‘ideal’ material to be used for the hull of 36 Water Metro ferries to be operated in Greater Kochi area, Kochi Metro Rail Limited (KMRL) has decided to include aluminium as an option.
The metro agency has published a corrigendum in its tender to procure the vessels that form part of a ₹747-crore project to revive water transport in the region. It had earlier zeroed in on marine-grade steel for the hull and fibre reinforced plastic (FRP) for the deck of the ferries.
Recycling
“Though many prefer FRP material for hull, it was decided not to opt for it since it cannot be recycled after the 25-year life cycle of each vessel. This leaves us with two options — steel or aluminium for the hull. The deck will be made of FRP. Thus, a corrigendum has been published and the last date to submit tenders extended by 14 days from June 29,” said a senior KMRL official.
Naval architects stated that steel needs least capital expenditure and can better withstand impact as compared to vessels that use FRP or aluminium to build the hull. On the flip side, they cite how operational expenses will be around 35% more during each steel-hulled vessel’s life cycle, since steel is heavier, affecting fuel efficiency. It also needs more frequent maintenance and painting to prevent corrosion.
The life cycle cost of each vessel works out to approximately ₹16 crore for steel, ₹11 crore for FRP and ₹12 crore for an aluminium-hull ferry.
Moreover, aluminium and FRP are more suited to operate on solar power. Though heavier and costlier than FRP, aluminium hulled vessels perform almost on par with FRP ones. They are also safer, according to naval architects.
Order will be placed for more ferries depending on the patronage for the first batch of vessels. The metro agency has plans to introduce 100 and 50-seater vessels across navigable waterbodies in Kochi.
