Surfer Yarns: Jim Banks On Where To Put The Damn Fins

7 Mar 2018 3 Share

Jim Banks

Surf Legend

True Tales From Lives Spent in the Brine and the Bay

Not the fin(s) in question, but a fin by Jim nonetheless. Photo:

Not the fin(s) in question, but a fin by Jim nonetheless. Photo:


Okay, confession time...

The real truth is that I’m not interested in making good surfboards.

I’ve spent a lifetime building good surfboards, and myself and my customers have had a lot of fun over the years surfing them. But to be honest, building good surfboards doesn’t interest me.

My real passion is to build magic surfboards. I’ve had enough of them over the years now to know that I don’t want anything less. It’s just one of those things, once you've tasted the good stuff there’s no turning back.

And so here’s my current dilemma. I’m designing a new twin keel fish based on my MKIV series. The MKIV is a single concave design that has been constantly evolving ever since I fell in love with my very first twin keel fish build back in 2005. Over the years, it has constantly evolved through various configurations as the MKI, the MKII and the MKIII, and now the MKIV is a finely tuned, very reliable twin keel fish that you can surf in waves from ankle high to double overhead. And its the thousands of hours of R&D behind it that enable it to do so.


I have a good buddy who has been begging me to recreate his original MKIII. The thing is so beat up, and surfed to death, that it’s just not surfable any more. So for years he’s been begging me to build him a copy of it. And for years I have been thinking that it’s just because it was his very first twin keel fish and that, like the rest of us, he was blown away by how well they surfed. But he was insistent that he felt indestructable on this board and couldn't do a thing wrong on it. So finally, we pulled out the poor old beaten board from a dark corner of his shed and took to what was left of it with some straight edges, rulers and a camera.

There were two surprises. One, the concave was set up completely differently to current designs. And two, the board had way more rocker than I expected. To my understanding, both of these design aspects shouldn’t work that well as they were and be inferior to the current designs, but I’ve been making surfboards long enough to know that the one thing surfboard design will always do is surprise me. And so I got to work designing a board with these discarded design elements.

Now creating a new design is a lot of work, especially when trying to incorporate design aspects that, to my thinking, shouldn’t work that well. But after many hours of inputting the the critical measurements and images of this old MKIII, and then fitting this in with everything that I’ve learnt since, I finally arrive at what I think is a good balance of capturing the key discarded design aspects while integrating them cleanly with all my latest design knowledge.

So, now I’m at the factory. The board’s come off the cutting machine looking very clean and all the curves are sitting in well with each other. I especially like the way the rail tapers as it approaches the tip of the tail, and the board shapes up nice. Now it’s almost ready to throw out the shaping room door to get finned, laminated, sanded and finished.

But there's one more thing to consider…

Where am I going to put the damn fins?

My first thought, because of the different way both the concave and rocker are configured, is that I’m going to need to move the fins further back than what I usually do. But I don’t want to move them as far back as the original MKIII, as I think the board will benefit from having them further forward than that.

But just how far forward is dilemma number one. Too far forward and the tail will let go too easily, making the board spin out and difficult to control. Not far enough forward and the board will feel stiff and lose speed.

Dilemma number two is how much to toe them in. If the fins are too parallel to the stringer, the board will track and surf horribly. Too much toe in and we’ll start to have drag issues, causing a loss of speed as well as a possible issue of the board oversteering through turns.

Dilemma number three is how much cant to put in the fins. Cant is how much the top of the fin is splayed out from the bottom of the fin. For a standard board, somewhere around seven degrees off vertical is pretty nice. But fishes are a little different to standard boards and usually require different angles. But, just like standard boards, excessive cant will cause the board to lift up out of the water too much through turns. Not enough and the board will feel sticky and very unfriendly.

So, now not only do I have to factor in all of these aspects, and calculate the right combination of them all, but I have to do all this while considering the significant changes that I’ve made to the board’s rocker and bottom contours. And even though I now have a vast amount of knowledge and experience in surfboard design, combining all these elements to get it just right is still a bit of dart throw. Especially when my goal is not to make a good board, but a magic one…

Years ago, I built myself an eight foot gun, and I really had no idea of where to exactly put the fins. So, when I finished shaping the board, I grabbed a set of fins and placed them on the bottom of the board, moving them around until they looked just right and went with that, disregarding all previous measurements, calculations and records. It turned out to be a magic eight footer and the fin placement was perfect. Unfortunately, it came off the roof of my old Nissan Patrol in the desert north of Carnarvon after only a few surfs on it, and I never saw it again.

But what this taught me, other than to always check your board is tied on, is that over the years I have acquired an inbuilt knowing from decades of building surfboards. An intuition that just kinda knows where to put the fins. Of course there is a battle that goes on whenever I do this because my logical mind is fiercely arguing to use my previous calculations and the fin position charts that I’ve spent hundreds of hours creating to arrive at the perfect fin position, and is always much happier when I do so.

But years of trial and error has taught me to trust my intuition, that it already knows exactly where to put the fins. And so I've got it to the point where even when I’m creating a new design such as this one, I don't even place the fins on the bottom of the board. Just by moving my ruler up and down the board, I will get a feeling where the right spot is, what the toe in needs to be and just how much cant to set it at.

But still, if I had to tell you what’s the perfect placement for the damn fins, I couldn’t actually tell you…

I know, but I couldn’t tell you…

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