A PANAMAX bulk vessel will have an underwater hull area of up to 12,000 m2. It’s the equivalent area of 10 Olympic size swimming pools. Vessels larger than this will of course have larger underwater hull areas
That is a lot of steel area that could get covered in fouling (barnacles, slime, weed etc), which both slows the ship down and creates what legislators see as the next big issue in battle against invasive species, and can hugely impact vessel performance.
The same issue goes for the vessel’s propeller.
Hull coating selection is a big issue therefore, especially when considering that a hull will be coated with more than one layer, and the costs are not insignificant.
Jotun, Hempel, Akzo Nobel and the other coatings manufacturers treat their products like a technology, investing in significant research to come up with the next best thing.
The issue of a hull coating is not as much what it can do, as what it does not do. Superior hull coatings will not allow the hull to collect fouling and will not degrade during its lifetime. And the lifetime of coating is usually measured in terms of the five year drydock cycle.
As fuel prices rose in 2010 so did industry concern about measuring the change in hull and propeller performance, and this led to the creation of ISO 19030 in 2016.
Oil prices may have dropped by then, but the issue of performance has remained critical. Software makers offer a range of measurement systems and the coating makers regularly update their portfolio of products.
Akzo Nobel recently announced a remarkable new weapon in this battle, the use of LED lights on a ships hull. These LED lights emit ultraviolet light that prevents antifouling.
Another product by Sweden’s I-Tech, called Selektope, is a hull coating additive that acts as a bio-repellent. The company has been publishing promising test results and has deals to have the additive in some of the coating products of Hempel and Chugoku Marine Paints.
The ISO standard 19030 is formally known as “Measurement of changes in hull and propeller performance” and comes in three separate parts. The expectations of the ISO standard are high, with shipowner users now wanting to get granular detail out of it.
ISO 19030 is, said Tom Evensen from Norwegian coating maker Jotun during a Fathom SmartTALK, a fantastic first step. IT can give a good indication of a vessel’s performance trends.
Nearly all his customer meetings involve the client asking at some point if one can separate propeller and hull performance, to get an indication of whether the hull would need cleaning he said.
While the standard is welcome, it does have its flaws still, and Evensen suggests that when owners are using it to make decisions about when to make a dive inspection it is perfectly suited to determining when this may be needed and when an in-water hull cleaning should be undertaken.
Torque is the turning force of a propeller shaft, thrust is push of the propeller against the water and the resultant forward motion of the ship. Thus, thrust could cause compression of the shaft while torque creates twist.
Being able to measure, to the minutest detail any changes can be an indication of performance changes in the vessel. Increased resistance of the hull, reduced power from the engine, damaged propellers or poor shaft liner or seal conditions could all influence measurements.
A number of companies offer advanced shaft sensors for the maritime industry, and the technology is getting smarter.
VAF instruments, one of the companies with solutions, has recently developed an optical sensor to measure thrust and torque in one sensor.
“A combination of accurate thrust and torque measurement will allow you to separate the hull performance from the propeller performance and moreover will result in more precise measurement of hull fouling,” said the company.
The accuracy of any performance measurement will be determined by the quality of the data an assessment system can use. The problem is there are many variables, and even the benchmarking of the data has proven to be problematic.
Maurizio D’Amico told SmartTALK that newbuilding sea trials, undertaken when a vessel is handed over from shipyard to owner are not robust enough, that the correction factors applied are too heavy. HE wants to see a year of data collected from a newbuilding to build u a more accurate performance benchmark, and upon which tools like ISO 19030 can be based.
And Daniel Schmode from DNV GL also points to the correction factors in ISO 19030 as needing some adjustment
“When a vessel sees harsh winds the performance index shows a better hull performance, but hull performance cannot change from one day to another, but when wind changes we see the hull performance changes and this can be improved, and we can see a gap, by further developing the ISO and the corrections,” he said.
Bunker prices will remain a challenge for the industry. Depending on your comparison points, you can argue they are low or high as they roller coaster in price over the last decade following cruse price trends. The 2020 fuel oil rule change will be an added concern, due mostly to cost risks, so having a vessel performance strategy will be a crucial strategy, one that D’Amico shipping introduced across tis fleet and Maurizio D’Amico share in detail on SmartTALK
“It all depends what you want to do with the data,” he said, explaining that the first step is to analyse the voyage consumption in total. ‘” This is money spent either by yourself or the customer, it does not matter, we are talking about fleet performance and we have to be accountable with this.”
Then a ship operator needs to regularly interact with the data, and for D’Amico Shipping this is a monthly task, to see the good and poor performing vessels in a fleet.
“You need to understand that two vessels from the same yards, but different routes and different maintenance history can have different consumption, and this may be because of the condition of the main engine, how well a master can follow the route of the vessel,” he said.
There’s a lot of operational parameters that can influence a vessel’s performance. But if a ship operator wants to make changes or give charter clients the information to make informed changes, they need to collect the right data.