As shipowners plan dry dockings to install ballast water treatment technology from September, they should not miss the opportunity to upgrade other crucial ships systems
One of the biggest ever legislated-for retrofit programmes begins this September. All ships more than two years old (and heavier than 400 gt) that are not already equipped with ballast water treatment systems (BWTS) – around 26,000 vessels according to Wärtsilä - will need to install them before 8 September 2024. For astute shipowners, the enforced drydock and expenditure at least offers an opportunity to minimise other expenses.
“It would be bold to assume all shipowners will upgrade other systems as well,” says Wärtsilä Seals & Bearings manager, OEM and environmental solutions, Ben Tornberg. “But it is a logical decision. It is crucial to minimise downtime for the vessel.”
Downtime is a key consideration for some major works. One example is upgrading seals, which prevent lubricant leakage into or out of the bearing system. This equipment has been particularly sensitive since the US Environmental Protection Agency released its 2013 Vessel General Permit (VGP), with strict requirements for the type of lubricants that can be used at ship interfaces with seawater.
As an example, upgrading from a conventional oil-lubricated to a water-lubricated stern tube – and hence both cutting operating cost and complying with US environmental requirements – can take up to 40 days. With a ballast water treatment retrofit taking up to 20 days, overlapping the two jobs makes commercial sense.
Water lubrication does not make sense in all retrofit cases and choosing the right environmentally acceptable lubricants in line with the VGP can be a difficult consideration. Another way of achieving a VGP-compliant stern tube sealing is to separate oil from the seawater by an air barrier. Wärtsilä’s Airguard sealing system uses compressed air applied to the void space between the seal rings. This flow of air into the void is automatically set higher than the seawater pressure, resulting in a small amount of air forced out into the seawater. Any seawater or oil that infiltrates the void space is drained inwards, preventing oil from leaking into seawater.
There are further benefits, says Mr Tornberg. “The air seal uses a double spacer which enables an additional shift of the sealing position on the liner without removing the shaft or propeller. This further reduces operating costs through extended liner life and simplified service – in other words, longer time between overhauls and longer life of seals.”
Another easy win while in drydock is to check shaft alignment. This can indicate whether bearings are in good condition – if bearings don’t function properly the propeller shaft will bend, jeopardising its ability to sail. Checking shaft alignment can either be done statically or, if needed, on the move. For example, Wärtsilä’s portable condition-based monitoring (PCBM) tool can be mounted in one working day and then sails along with the ship to the next harbour, where data is collected for analysis and a repair proposal is given.
The Wärtsilä PCBM system measures vibration levels, temperature, runout, whirling, movement, torque, stress and position of the equipment. It can be used for investigation of gearboxes, engines, stern tubes, stern tube seals, intermediated bearings, water jets, propellers, generators and thrust bearings. Used wisely – for example before an upcoming drydock – the Wärtsilä PCBM can help to make the most of time in dock, says Mr Tornberg.
“We can check how healthy your system is and give advice on actions for your upcoming docking to ensure smooth and continuous operation,” he says.
For all the cutting-edge services companies can offer shipowners at drydock, one factor is the most important, says Mr Tornberg; get your orders in early. He concludes: “Don’t forget to order your spares in good time. The sooner you send an enquiry to us, the sooner we can confirm a date and the higher the probability of having parts and people on-site at the desired time.”
Owners may have no choice but to spend on ballast water systems, but for those with a wider view there are still ways to drive value from the required retrofitting schedule.