More discussion on different fins

By Dave Dalkiewicz Contributing Writer

(July 21, 2023) This article will continue with our discussion on fins.

Last time we concluded with singles and twin fins in popular usage. The era was the early years of the 1970s. Surf boards had become quite short and the search was on for ways to make them go faster and perform better.

Around 1973, a radical new design emerged from Malcom and Duncan Campbell, two brothers who, with the help of their father, came up with the idea. It consisted of a single fin and two more tapered fins, placed outside toward the rails.

There were also two deep concaves or channels between the center single fin and the outside tapered fins.

All of this was based on the Venturi principle which states that water and other fluids cannot be compressed. If the flow of the water meets with a constricted area, as in a large pipe going into a smaller one, the flow of the water goes faster.

In an attempt to not make things too complicated, suffice to say that this created quite a “buzz” in the surfing world. The Campbell Brothers wanted to share their idea and got in touch with large manufacturers of the day.

Bing Copeland of Bing Surfboards and Mike Eaton, Bing’s head shaper, were quite intrigued with the idea and decided to go forward and build an extensive campaign around what came to be known as the “Bonzer.” The term is Australian slang for something first rate or excellent.

These days the term is probably considered to be rather archaic and oldfashioned but as has been said on many occasions, old school is good school.

Some of the Bonzers had a single concave placed forward of the fin area and this single to double concave idea is seen extensively in many surfboards today.

I tend to think of them as moderate Bonzers and is probably due to a lot of boards made without nearly as much thickness.

Bonzers were not the easiest boards to make, though.

Mike Eaton found ways to quicken the process, but this was just in the shaping. This isn’t said to lessen the step of shaping. After all it’s the foundation of the surfboard.

Every step in the process is important and there are many more steps of surf board building. I remember reading about a sign in a sander’s work room to