Different fin setup for SUP boards
Fin setup is something we talk a lot about at Honu HQ. It's a confusing topic for many as surfing culture trends influence SUP design, wrongly or rightly, making it harder for paddleboarders to understand why one is better or worse than the other.
Why do our boards only have one fin where most have three?
Three must be better than one... Right?
To understand this, we need to go back and understand more about the different fin setups and how they work and why. It's essential to understand the general concept as it applies to surfboards as the reference is more easily understood because we can include how the board with the associated fin setup is being used.
The single fin has it roots firmly in surfing with the first surfboards all having a single large fin. Even today, longboards and even smaller boards down to 7'6 can have a single fin with riders appreciating how this feels on the wave. So how does it feel? The single fin has the characteristic of tracking nicely in a straight line with large sweeping arcs for turning. It is stable and predictable with minimal drag. I.e. Excellent straight-line speed and tracking. The larger centre fin provides the most amount of stability on the board as when you wobble side to side the fin is in the centre of that fulcrum point pushing against the water.
The twin fin has gained popularity in surfing circles over the last couple of years. This setup has two medium-sized fins on the outside of the board just slightly forward of where you would have a centre fin. This makes the board feel very fast in a straight line, but has solid turns when on the rail due to the larger surface area of the fin. The fin setup suits fast, aggressive turns with high rail to rail speed. The downside of the fin setup is that the board feels loose, and when applied to a SUP there is some loss of stability.
The Thruster fin setup revolutionized the surfing world in the early 80's when some clever shapers in Australia squared off the back of a board and included a smaller single fin that matched the size of the mid-sized side fins. This setup provided the stability you get from a single fin with the powerful turning ability of a twin fin. This is by far the most popular fin setup in surfing still today.
This is the setup that describes a single large fin that also has the side fins, also called "bite fins". The bite fins are there to help the board turn on it rail. They should be angled in towards the nose of the board so that when the board is turning on its rail, they are pushing squarely again the water to provide some purchase and "bite" in the water.
Best fin Setup for SUP's
For any SUP that is going to spend most of it's time cruising on flat water, there is no purpose for side fins. They do nothing except create drag, if they are installed properly. And I say that because probably 90% of SUP's have them installed incorrectly. I.e. parallel to the rail, or pointing straight ahead like the centre fin.
And so, if that is true, why do most SUP companies have three fins on their boards? This is a great question, and the answer is somewhat silly. They do it because that is what folks think they should have, and they look better in photos. I.e. They look more like a surfboard, and most surfboards have three fins. Stupid, I know, but this is the reality.
So what styles of paddleboards and conditions are suited to each fin configurations?
Any board intended to spend its life on flat water going in a straight line most of the time. Touring or racing SUP's should only have a centre fin, no exception. Speed, straight-line tracking, stability. Simple! We also stuck with a single fin on Honu allrounder boards such as the Byron, Fairlight & Airlie. We did this because they are designed to spend most of their life on flat water or go into some smaller surf on occasion for the average paddleboarder. In this case, the fact the board will track nicely on a straight line across the wave is a welcome feature, not a drawback.
The only valid reason to have a twin fin setup on a paddleboard is on compact iSUPs where you want the board to be able to fold down the centre. You can't fold the board if there is a finbox in the way, so you shift two to the outside of the board. The characteristics and conditions needed for this fin setup to work well don't exist in SUP's, especially inflatable ones. Even performance-orientated fibreglass SUP'S aren't well suited to a twin fin setup. So while there is some stability penalty for the twin fin setup on a compact board, the idea is to have the smallest possible bag, and so that is a compromise many are happy to make.
The thruster fin setup does have a place with paddleboards, and as you would expect, it is on surf-specific models. To get the most from this setup you need to be turning your board at speed and on its rail. The only actual condition where this happens is in the surf, so surfing SUP's can benefit from the thruster fin setup which is what any future Surf-specific model from Honu will have.
Blending the advantages of a single fin with the thruster setup is the 1+2 fin configuration. SUP's can use this setup when wanting to have the ability to tune how the board will perform. You can leave the side fins off and get the single fin feel, or put them in and get the purchase and "bite" when turning at speed. This is why our Bondi has this setup and with high-performance honeycomb fins. When you do take the Bondi into some mid-sized surf and you want it to turn on its rail, these fins are making that possible. You will see many paddleboards with side fins facing straight up and down the board. Whether they are fixed in place or removable, for all intentions, they are useless.