Structural evaluation of a pusher-tug vessel to comply with the requirements for navigation in ice covered waters

Abstract

The design of a standalone ice breaker vessel destined for inland navigation could be a costly solution for a temporary problem, due to the limited period of time when the vessel is engaged in ice breaking operations. The Romanian Authorities have in their possession a dedicated ice breaker, Perseus, destinated to clear the navigation path on the Maritime Danube River but which cannot navigate upstream on the Fluvial Danube River due to its draft limitations. As a consequence, most vessels trading from Braila and upstream are exposed to high risks due to the possibility of being trapped in ice formations that could be dangerous for both for the crew and vessels during the winter season. A viable solution is represented by designing a removable ice breaker module that could be attached to the existing fleet of pusher vessels. Since it is not a stand-alone vessel, it will not require a dedicated crew onboard and will only operate when ice dams are created along the river and the navigation path needs to be cleared. The existing fleet of pusher vessels is not prepared to navigate in ice covered water and thus structural reinforcement are required to comply with the requirements provided by classification society. The current paper presents the evaluation of the existing structure of a pusher vessel and proposes means of reinforcement to comply with ICE B class notation provided by DNV Class Society. The paper will conclude on the definition of the ice belt area (LIWL, UIWL) along the ship’s side and will provide scantling information for the new structure within the ice belt area.