The Finnish ice class rules, also named the Baltic ice class, requires vessels whose keel was laid before 1 September 2003 to prove that the installed engine power complies with the minimum requirements. Otherwise, the vessels can be downgraded or lose their ice class. There are some solutions to this challenge, however.
Operators of vessels with ice class should be aware that the Finnish Transport Safety Agency (TRAFI) requires vessels whose keel was laid before 1 September 2003 to comply with the minimum power requirement of the current Finnish ice class rules (ref. TRAFI/31298/03.04.01.00/2010) when they reach the age of 20. The vessel can only keep its current Baltic ice class when the installed engine power complies with the minimum requirement. This engine power requirement is higher than the one which the vessel had originally been designed with.
What happens then if the vessel does not comply? If the minimum power requirement for the Baltic ice class is not met, lower ice classes can be assigned, provided the power of the ship is sufficient. This means that the vessel could be downgraded in ice class or lose the ice class altogether.
The possible lowering of the Baltic ice class does not affect the ice class given by the class society as such, but it will influence Finnish fairway dues and result in traffic limitations to Finnish and Swedish ports.
There are three options for proving that the engine power requirement is met:
- Simple but conservative calculation formulas according to TRAFI rules. The advantage of these formulas is that information about the hull form is not needed.
- If the vessel does not comply with the simple formulas, more complex calculations can be carried out using certain hull form data as input. The advantage is that these calculations are less conservative and require less engine power. At the same time, to determine the input values, a lines plan or electronic hull form representation is needed. For older vessels, such data can be difficult to obtain.
- Model tests in an ice basin can be carried out to determine the resistance of the hull in ice and to assess the power needed. The model tests normally result in much lower power requirement, but they are expensive and time-consuming. In addition, information about the hull lines is also needed.
Customers have the option to carry out the calculations inhouse, by an engineering company. In this case DNV GL will be able to check the calculations, but TRAFI will ultimately approve them. Otherwise, DNV GL is also able to carry out the calculations on behalf of our customers. It is also possible to search in the database for sister vessels for which a TRAFI acceptance is already available and to use this for further vessels.
- Timely action is required to avoid downgrading or loss of ice class for older vessels (keel laid before 1 September 2003, reaching 20 years of age).
- DNV GL recommends to submit the ice powering calculations to TRAFI for approval.
Sea News, October 2