DEFLOW BONZER 6.5" | FIBERGLASS SINGLE FIN FOR BONZER SURFBOARD

The fin the Campbell brothers would have chosen: Deflow Bonzer 6.5" for boards that think differently

Curiosity has a special way of taking you to unexpected places. The Bonzer is one of the best examples of this in the history of surfboard design: a system born from the Campbell brothers' obsession with understanding how water moves beneath a board. The Deflow Bonzer 6.5" fin is designed to work in perfect synergy with any Bonzer board, enhancing the efficient water flow that makes the system so special. Fiberglass, controlled flex, and calculated dimensions ensure that speed and control are two sides of the same coin. Thank you for staying curious.

WHY THIS FIN MAKES THE DIFFERENCE

A Bonzer board without the right fin is like the system without its central motor. The Bonzer works because everything works together: the concave V-bottom, the side bites, and the center fin. The Deflow Bonzer 6.5" has been designed for that specific role — it is not a generic single fin adapted for the purpose, but a fin designed from scratch to optimize the water flow that the Bonzer system already prepares.

• Specifically designed for Bonzer boards — The dimensions, outline, and flex of this fin are calibrated to work in synergy with the bottom geometry and side bites of a Bonzer board, rather than as a multi-purpose fin.
• Fiberglass — Construction that balances stiffness and response. The contained (low) flex transmits water energy directly without absorbing speed — exactly what the Bonzer system needs at its center.
• Precise measurements: 6.5" height — 135.3 mm base and 165.1 mm height for an area of 25.52 cm². A medium-sized fin that meets the needs of most Bonzer boards without oversizing the setup.
• US Box compatible — The universal standard for single fins and Bonzer boards. Direct installation without adapters.
• Side bite capability — If conditions demand it or you want more control, the system allows for the addition of side bites for a 2+1 setup that extends performance without compromising the Bonzer essence.
• For curious surfers — If you already own a Bonzer board or are thinking about exploring that world, this fin is the right companion to start with.

TECHNICAL SPECIFICATIONS

• Construction — Fiberglass
• Flex — Little
• Box system — US Box
• Type — Single fin (center fin for Bonzer)
• Base — 135.3 mm (5.3")
• Height — 165.1 mm (6.5")
• Area — 25.52 cm²
• Use in 2+1 — Yes, compatible with side bites
• Compatible boards — Any Bonzer board with a US Box

ADVICE FROM OUR EXPERTS

If this is your first fin for a Bonzer board, the 6.5" is the most balanced starting point. Its 25.52 cm² area offers enough traction and control for most conditions without adding unnecessary drag. In hollow, powerful waves, this fin alone is all you need. If conditions are softer or you want more rail control, add the side bites — the difference is immediate. And if you have never surfed a Bonzer: give it time. The first sessions are for adaptation; by the third or fourth, the water flow and the speed out of turns will speak for themselves.
— Core Surfing Team

DEFLOW GUARANTEE — "OUR LOVE FOR THE SEA BROUGHT US HERE"

Deflow was born in Zarautz, in the heart of Basque surfing, by a group of passionate surfers with a clear mission: to design and manufacture fins that really work, using the best materials and without compromising on quality. From high-performance shortboard fins to single fins and special fins for alternative shapes, Deflow has built an international reputation based on the consistency of design, materials, and performance.

Deflow's line of special fins — where the Bonzer lives — represents their commitment to surfers who look beyond the standard thruster. Because the curiosity that led the Campbell brothers to invent the Bonzer in the 70s is the same curiosity that leads Deflow to keep designing fins for shapes that the mainstream market ignores.

A BIT OF HISTORY: THE BONZER AND THE CAMPBELL BROTHERS

The Bonzer is one of the most revolutionary designs in surfing history. Malcolm and Dale Campbell, surfers and innovators from Santa Barbara (California), developed it in the 70s, driven by their curiosity about hydrodynamics. The original Bonzer system combined a larger center fin with two smaller side fins (runners) and a concave V-bottom — all designed to allow water to flow efficiently through the tail of the board, generating more speed, stability, and control.

Although it did not see immediate mass adoption, the Bonzer gained loyal followers for its ability to provide a smooth, fast surfing feel that was especially effective in hollow waves. Over time, its design principles have influenced modern surfboard development, and the system remains respected today for its innovative approach to hydrodynamics.

USAGE AND CARE

• Installation — Insert the fin into the US Box and adjust the position according to your setup preferences. Tighten the screw with the appropriate key until it is completely secure. Do not overtighten.
• Positioning — On a classic Bonzer, the center fin is placed slightly further forward than a conventional single fin to optimize water flow alongside the side bites. Consult your board shaper's recommendations.
• Side bites — If you add side bites, ensure the set is compatible with your board and that the positioning of the three elements is consistent with the board's bottom design.
• Cleaning — Rinse with fresh water after each session. Dry before storing.
• Inspection — Periodically inspect the fiberglass laminate. In the event of any cracks or chipping, stop using the fin.

SIZE GUIDE

Model	Base	Height	Area	Recommended board
Bonzer 6.5"	135.3 mm (5.3")	165.1 mm (6.5")	25.52 cm²	Bonzer boards with US Box, general use

If other Bonzer Deflow sizes are available in your store, consult with the Core Surfing team to find the size that best fits the specific design of your board.

READY TO DISCOVER WHAT THE BONZER CAN DO FOR YOUR SURFING?

The Deflow Bonzer 6.5" is available at Core Surfing Shop with free shipping on orders over €50 and delivery in 24-48 hours throughout mainland Spain. Official Deflow guarantee included.