Length is Back
After years of boards becoming shorter, recent seasons saw a sales surge in "mid-length" or longboard shapes, typically 5'10" to 6'2". These boards blend SUP stability with foil glide.
The Physics of Displacement
The main advantage is hull speed. In light winds, a short board pushes water while a longer board cuts through it. This makes waterstarts easier because the board gains speed on the surface before the foil engages. This concept is supported by designs from Starboard and other major brands.
Stability in Rough Water
These modern longboards feature wider noses, boosting rebound in chop. When a rider touches down unexpectedly, the long nose helps the board skip back up onto the foil rather than diving. This suits intermediate riders bridging the gap between freestyle and wave riding.
Displacement Hull Hydrodynamics
Unlike a planing hull that needs to skim on top of the water to reduce drag, a displacement hull is designed to slice through it. By parting the water efficiently, these narrow shapes minimize the "bow wave" resistance that traps shorter, wider boards at sub-foiling speeds.
This efficiency allows a rider to generate speed with a smaller wing or in lighter wind, lowering the threshold for takeoff.
Managing Swing Weight
The trade-off for length is rotational inertia, or swing weight. A 6'0" board is harder to whip around in a turn than a 4'8". However, designers are mitigating this by reducing volume in the nose and tail, concentrating mass near the mast track.
Rider Tip: Shifting your foil mast forward in the track can help counterbalance the swing weight of a longer nose, making the board feel shorter than it is during maneuvers.
Touchdown Recovery Physics
One of the biggest perks of the "mid-length" shape is forgiveness. On a short board, a touchdown often acts as a brake, throwing the rider forward. A displacement hull, with its narrow entry and parallel rails, maintains momentum upon contact.
This "skip" effect gives the rider a split second to shift weight back and pump the foil, often saving the ride without ever fully stopping.
Efficiency Gains
Models like GONG’s Cruzader utilize this shape to pump farther than shorter shapes. The trend is moving toward carbon hybrid constructions that drop the total board weight while providing a speed gain.
Sources & Further Reading
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