Before fins, surfboards were so big and heavy that most surfing was done in a straight line back to shore. Slight control over the big, heavy boards could be achieved by using your feet.
Using your back foot as a fin continued with the early evolutions of the surfboard itself – the lighter, smaller surfboards of the early 20th century made carving and turning a little easier.
Invention of the Surfboard Fin
Tom Blake, who had a number of inventions including the hollow surfboard, lifeguard equipment, waterproof camera housing, and even windsurfing to some extent, is credited with the invention of the surfboard fin.
In 1935, Blake attached a 4” deep by 12” long speed boat keel to the bottom of one of his surfboards. From the first surf with the new fin, Blake knew he was on to something. The control it provided was unlike anything he’d experienced before.
The long, narrow keel remained mostly unchanged through the 40’s, when surfers/shapers/inventors like Bob Simmons and George Greenough started to iterate on the design of the fin.
Twin Fin Surfboards
Simmons, who is often credited as the father of the modern surfboard, began building his own surfboards based on his studies in hydrodynamics.
Through the 40s and 50s, Simmons used twin fins on each side of with wide-tailed boards. The combination of the board design and the fins resulted in a surfboard with speed and control that hadn’t been seen before.
Development and iteration of Simmon’s ideas took a pause following his death in 1954 while surfing at Windansea.
Longboards & Single Fins
Longboards with single fins continued to be the norm for much of the mid 20th century. Construction materials evolved from solid wood board to hollow board to balsa wood and fiberglass boards and finally to polyurethane foam boards.
By the 1960’s, polyurethane foam and fiberglass boards had become the standard. Fins were constructed of wood or fiberglass and were glassed onto the bottoms of the boards.
The majority of longboard fins, or skegs, took the form of the “D” shape, which added stability and the ability to tightly pivot. These fins were great for classic styles of surfing like noseriding, cross-stepping, and hot-dogging, but didn’t aid much in the progression of the sport.
Flex & Aspect Ratio in Surf Fins
In the early 1960’s, George Greenough began to experiment with fins that were modeled after the dorsal fins on tuna and dolphins.
The flex and drag reduction of Greenough’s fins had a noticeable effect on speed, turning, and overall performance.
Greenough primarily made his fins for use on kneeboards, but his design ideas were translated to a surfboard by shaper Bob McTavish.
McTavish shaped a shorter board with a high-aspect-ratio single fin that really sparked the shortboard revolution. Once people saw what it could do when Nat Young won the World Contest with a surfing style that hadn’t really been seen before, surfers and shapers alike took notice.
Multi-Fin Designs Return
Steve Lis began experimenting with twin fin fish surfboards in the 1960s and 70s. The twin fin setup gained momentum when a handful of Australian surfers began winning contests and titles on twins.
The early 1970s is also when the Campbell brothers began to experiment with and design the 5-fin Bonzer surfboard, which never gained much traction, but are beginning to become more popular more recently.
In the 1980s, Simon Anderson was looking for a board that offered more stability and control in bigger surf than the twin or single couldn’t offer. He designed a three-fin board with fins of equal size – two on the rails and one in the middle – which he called the thruster. The thruster design was exactly what Anderson needed, and helped him find competitive success with it almost immediately.
The thruster, which has remained largely unchanged, went on to become the most popular fin setup for professional and recreational surfers alike.
Quad fin setups began to evolve around the same time, a some surfers found the center fin of the thruster too restrictive. Where thrusters allowed for speed generation and snappy surfing, quads enabled natural speed, looseness, and drive out of turns and higher on the wave.
Removal Fin Systems
Much of the surfboard’s fin evolution happened with the fins still glassed directly onto the bottom of the board.
The first commercial available and popular removable and adjustable fin box was developed by Bill Bahne of Fins Unlimited in the 60s. The design accepted a variety of fins and allowed for easy forward and backwards adjustment. It has held in popularity and is still widely accepted as the industry standard for single fins today.
In the early 1990s, FCS designed their removable plug and tab system for surfboard fins.
The designed sparked a wave of new removable and adjustable fin systems from other companies including Futures, ProBox, LokBox, O’Fish’L, and Red-X.
Today, the majority of surfboards shaped and sold come with some sort of removable fin systems.
Removable surfboard fins make fin experimentation extremely accessible to every surfer. A different feeling for your board is as simple as plug and play.
Since the fin’s inception, there have been countless shapes, designs, and gimmicks that have been tried, but it’s the removable fin system that has resurrected many old designs and facilitated new ones.
With a quick fin swap and the tightening of a few screws, the “ah-ha” moments and new discoveries are way more easily attained, but just as sweet as they were as the fin was evolving in the 40s and 50s.