08/26/2026
*Link in bio for complete document* Real-world testing → Engineering → Simulation → Validation → Back to the water.
Over the past five weeks, we completed an extensive engineering process on our 40’ catamaran center console—using real-world testing, 3D scanning, CAD, and CFD to diagnose and redesign its running surface.
During testing of our first 40’, we identified a stability issue around 50 mph, where the boat could become loose and develop a tendency to turn on its own.
Rather than make changes through trial and error, we wanted to understand exactly why.
EMS3D 3D scanned our existing hull mold and produced a high-fidelity mesh. Petestep reverse engineered that scan into CAD so they could simulate the actual hull geometry under the same conditions we experienced on the water.
The first CFD simulation confirmed our theory. The pressure and wetted-surface maps showed almost no meaningful pressure or water contact aft of the first step. More importantly, the CFD model leaned and veered to one side—reproducing the same behavior we experienced with the actual boat.
We had digitally recreated the problem.
From there, we began iterating. We reduced the step heights by one inch, revised the keel geometry and deadrise, and continued testing.
Water reattached aft of the steps, a substantial high-pressure region developed on the rear running surface, and the model became stable and tracked straight at 50 mph.
We then simulated a hard 50 mph turn. The hull leaned 18° into the turn, remained stable, and developed the pressure distribution we wanted.
Next: 90 mph.
After further refinement, the final CFD showed controlled pressure from front to rear, strong pressure on the aft running surface, reduced unnecessary wetted area—and a hull that tracked straight at 90 mph.
We then physically incorporated the CFD-developed geometry into the hull mold.
Five weeks from 3D scan to finished tooling.
The slides show the full process and before/after results.
Thank you EMS3D and Petestep for being a major part of this process.
