Simple and clean. All convex and flat bottom with a vee entry, flat middle section and vee ahead of the fins. Commonly made as a 6’10 but works well in shorter more traditional fish sizes like 5’10. The name derives from the thin foil, thinner center thickness around 2 1/2” and knifey rails for responsive rail to rail surfing. Adaptations can include adding double concave leading into the tail vee for a spicier ride.

knife fish

A tan dog with a pink bandana around its neck sitting on grass next to a white surfboard with yellow fins.
Custom surfboards with two yellow fins resting on a workbench in a workshop. Twin fin.
Lula Surfboards Man with long hair and beard holding a white surfboard standing against a beige wall, wearing a light-colored bucket hat, white shirt, green shorts, and sandals.
A surfboard in a workshop or garage environment, with tools and equipment in the background, leaning against a workbench, and wrapped in foam at the bottom.
A surfboard placed upright on a padded stand in a workshop. The surfboard has a light gray top with visible seams and black markings. The workshop has a blue wall with a wavy wooden shape, a black tool chest, and various tools and supplies scattered
A white surfboard standing upright on a grassy field with trees in the background under a partly cloudy sky.
A man holding a surfboard standing on a grassy area near the beach with the ocean in the background and blue sky above.
A man with curly blond hair and a red shirt is standing outdoors in a garden, holding a white surfboard upright. He is wearing sandals, and there are plants, bicycles, and gardening tools around him.
Two surfboards placed on a brick and concrete sidewalk near a brick wall and some plants with shadows cast by nearby leaves.
A white surfboard with blue fins on green grass near two palm trees.
A person standing on a sandy beach holding a surfboard, with tall palm trees and cloudy sky in the background. The beach has several people, some with umbrellas and others near the water, and a distant mountain range is visible across the water.
A surfboard stands in front of a garage or workshop wall. The garage has blue walls with paint splatters, a shelf with paint cans, and a workbench with various tools and supplies. An air compressor is visible on the floor behind the board.
A person in a black jacket and black cap kneeling behind a white surfboard with a yellow strip and text on it, in a dimly lit room with blue and yellow lockers.
Two surfboards with fins leaning against a fence on a concrete sidewalk.