​Can bridge simulations support conceptual design?

Within the EU Horizon project Holiship, MARIN has developed, together with partners, a Virtual Vessel Framework (VVF) in which real-time bridge simulations can be used to make key decisions in the concept design stage. This VVF can lead to a better performing ship or cost reductions.

Figure 3: Bird-eye view of sailed track into a basin in the Port of Rotterdam
Conceptual design is the art of balancing the various aspects of the design. This can range from fulfilling class rules and client requirements to applications in highly specialised domains. The early design stage is a process of the gradual reduction of uncertainty, i.e. mitigating risks financially, legally and technically. One of the complexities of conceptual design is that procedures and the decision sequence are not fixed at all. Some impacts from the result of decisions taken in an early design stage only reveal themselves in more advanced stages of the project. It may then be too difficult or even impossible to introduce major changes in the design.

Virtual sea trials improve ship design

Virtual sea trials are one of many possible applications for a VVF. One example is testing new manoeuvring configurations early on in the design of the vessel. By coupling hydrodynamic models and machinery models with a bridge simulator, the feel of the manoeuvring configuration can be tested in addition to the numerical evaluations. The various hydrodynamic and machinery models are coupled through the Remote Components Environment (RCE) developed by DLR, Germany and is illustrated in Figure 1.

Figure 1: Coupling of tools to the RCE
In order to demonstrate the VVF, a Damen Combi freighter was used in the Holiship project. Hydrodynamic forces derived from viscous flow calculations carried out by MARIN, a dynamic engine model from TNO and rudder forces and rudder steering controls from Van der Velden Marine Systems were connected to the bridge simulator via RCE, which is illustrated in Figure 2. In order to avoid time delay issues when running over the internet, RCE created offline response surfaces and tables which were connected to the bridge simulator software.

Figure 2: Schematic overview of coupled tools to MARIN’s bridge simulator

Bridge simulations were set up for eight typical harbour manoeuvring scenarios and carried out and assessed by an experienced captain. The simulations were performed for two rudder configurations: a full spade rudder and a flap rudder.

Bridge simulations were successfully carried out. The captain could clearly experience the difference in sailing for both rudders. Based on the assessment of the simulations the captain preferred the flap rudder over the spade rudder for this vessel. The advantages of the real-time bridge simulations are clear. The application of the VVF adds a lot of value to the concept design or retrofit of ships because the various manoeuvring scenarios cover the daily use of the vessel much better, and can be combined with the IMO’s prescribed manoeuvres.

This demonstration project showed the benefit of using the bridge simulator for manoeuvring solutions. However, the VVF platform can facilitate the connection of all sorts of machinery tools to the bridge simulator. Using this kind of simulation in an early stage contributes to key decisions and supports the concept stage for a large number of applications. In addition there is the added benefit that the concept stage is no longer limited to only a numerical assessment.