Mini Transat 2015 · Dominik Lenk

CFD Testing

CFD stands for ›Computational Fluid Dynamics‹. We are running some last minute tests before we start building the hull in order to improve the bow section.

One can build separate scale models for every variation of a boat that are tested in a towing tank to determine drag and behaviour of a hull shape. Unfortunately, this is costly and time-consuming and often not feasible for a Mini Transat campaign.

Pressure when beating to windward
Shear stress when beating to windward

Instead most scenarios can be computer simulated. The only thing to keep in mind is to decide from the beginning which problem needs to be solved. Otherwise the amount of data generated quickly gets too large.

During the ’13 Mini Transat the only boat with an extremely wide bow once again sailed very well. Even though in the end it only came second, it is still something to think about.

Small, wide and ROUND: The boat with the scow bow: 747. For comparison: 667.

The boat that ended up winning pursued an entirely different strategy: Pointy and thin. Nevertheless, the podium created some questions that we are now trying to answer using CFD analysis

Therefore, we are currently testing some bow variations at different speeds. Mostly we are looking for drag, wave generation and the boat’s pitch.

A simulation takes roughly one night. To save time we start a simulation and swap the hull halfway. This allows us to test two hull shapes in one go.

Even though CFD analysis can produce pretty pictures like the ones above, the numeric data produced is just as more important. The goal is to find a shape with the least amount of drag that lets the boat start planing as early as possible.