Schedule reliability
General information
RoRo's, RoPax, Container vessels and cruise vessels sail according a fixed schedule. Therefore, it is important to know if these vessels are able to keep their schedule.

Wind, waves and current cause additional resistance with respect to the calm water resistance. This so-called added resistance, increases the power demand. If the demand is higher than the capacity of the engine the ships speed decreases. This is called "involuntary" speed loss. The ships master can also reduce the velocity because of comfort and (fear for) damage to ship and cargo. This is called "voluntary" speed reduction.This comfort and damage issues can be related to slamming, green water and whipping and springing of the hull.

Services & Activities
Schedule reliability can be assessed by means of scenario simulations. During these simulations (round)trips are simulated stepwise. Each trip is simulated for hundreds of times and for several years. At each time step the maximum sustained speed is calculated accounting for engine limitations and the actual weather conditions. Furthermore the ship behaviour is evaluated and this input is used to asses "voluntary" speed reduction.
The duration of each trip is obtained for every voyage. The long term distribution of these durations is used to obtain the required service margin (see figure above). It also can account easily for seasonal variations.

Facilities & Tools
Schedule reliability is assessed by the Safetrans and Gulliver software tools. Details on these tools can be found here.

Most recent Schedule reliability papers presented by MARIN:
(complete overview of papers can be found under Publications)

OBELICS JIP successfully achieves goals
Ron Schoon & Eelco Frickel, MARIN Report, 2013

First images of cavitation and ventilation in waves
Gerco Hagesteijn & Joris Brouwer, MARIN Report, 2012

LAURA Phase 2 gets underway
Frans Kremer, MARIN Report, 2012

Live testing of fatigue predictions for USCG
Ingo Drummen, MARIN Report, 2012

MARIN gets to grip with the elusive Human Factor
Wendie Uitterhoeve, MARIN Report, 2011

Most recent Schedule reliability articles written for MARIN Report:
(complete overview of articles can be found under Publications)

OBELICS JIP successfully achieves goals
OBELICS, the Joint Industry Project on Operability of Ballasting and lifting operations of Extreme Loads with Integrated hydro dynamiCS, was just rounded off after two years of intense cooperation.

First images of cavitation and ventilation in waves
History was made on May 22 when the first-ever cavitating and ventilating images appeared on the monitors at MARIN’s new Depressurised Wave Basin.

LAURA Phase 2 gets underway
The “Launch and Recovery of any small navy craft” (LAURA) JIP enters its second phase and calls for new participants.

Live testing of fatigue predictions for USCG
One of the core services of MARIN is to carry out measurement campaigns on board ships at sea and to analyse the collected data for the development and validation of design tools. Currently, MARIN is carrying out an extensive...

MARIN gets to grip with the elusive Human Factor
As the maritime industry recognises the importance of the human factor, MARIN has taken the decision to step into this new and highly complex field.

Contact
For more information on how MARIN can help your organisation with schedule reliability assessments, please contact:

Seakeeping Department

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