A DNV project has demonstrated that passenger ships of over 20 years of age can also apply for in-water surveys (IWS) instead of drydocking.
Following the DNV analysis, The Bahamas Maritime Authority (BMA) removed the 20-year age limit, allowing applications for all passenger ships under the provisions described in a revised maritime notice.
DNV initiated the study in 2023 to investigate if the 20-year age limit for drydocking may be waived without having adverse effect on the ship’s maintenance.
The design, and most importantly the operation, of passenger ships differs significantly from typical cargo ships. While the rule-based design life of cargo ships is 20 to 25 years for strength/fatigue considerations, a passenger ship 20 years of age has only entered the middle of its lifecycle, as the life expectancy of a typical passenger ship is 40 years.
Passenger ship operators often re-route or change itineraries to avoid storms, significantly reducing the risk of extreme loading. Real time AIS data allows for the extraction of the actual encountered wave loading, which then can be compared with the design’s rule-based extreme and fatigue values from the DNV Nauticus Hull software.
The in-depth analysis of the historical survey records extending over the last 35 years of the DNV passenger ship fleet revealed that there is no increase in class survey findings for passenger ships over 20 years of age, compared to vessels younger than 20 years.
Furthermore, the analysis of the last 40 years’ damage records on the bottom structure and equipment revealed no major concerns or increased risks to the ship’s safety regarding strength, propulsion and steering/navigation.
These conclusions were well received by the BMA and opened the possibility for Bahamas-flagged ships to apply for a five-year drydocking period.
One important provision to qualify for the ‘one-in-five’ drydocking scheme is that a ship specific study must be prepared by DNV to evaluate the condition of the bottom or inner bottom structure and the propulsion, steering and navigation equipment.
The study will provide the BMA with a clear conclusion as to whether DNV supports the scheme for the subject vessel. This must be backed by the relevant documentation and/or calculations.
Passenger vessel shipmanagers are encouraged to perform additional surveys, and based on DNV recommendations, perform extra servicing and repairs during drydocking.
This should be undertaken alongside a targeted occasional survey and before the final BMA application for the in-water survey (IWS), which is less costly compared to a drydocking survey, DNV said.
