The choice of a fin system for your paddle board will impact its performance, versatility, and convenience of use. Fin systems differ in the type of mechanical system, and in the layout and positioning.
Broadly speaking, there are three overall categories of paddle board fin systems that you need to know about, and several basic configurations in use:
There is a certain convenience to having the fins permanently attached to the board, especially if they are shaped for performance and are unbreakable. Permanent fins mean you never show up at your paddling location and realize you left your fins at home, and you will never leave them in the water either.
If you’re the kind of person who doesn’t like tinkering with equipment, permanent fins may be the best solution for you.
Several fin attachment standards have been adopted over the years by the surfing industry and have been adapted for use on stand up paddle boards.
Examples of these are the US Standard Fin Box (US Box), which originated with “longboard” style surf boards and are used for the center fin on some models of stand up paddle board. FCS (Fin Control System)-compatible side fin boxes, which can be used with a plethora of specialty fins that can be purchased in any surf shop or from various suppliers online.
The advantage of universal fin boxes should be immediately apparent in the naming convention. Almost any fin designed for the box will work and they are readily replaceable.
These fins are produced in a variety of shapes, sizes and functions and give the paddler ultimate control over the set-up of the board.
Some paddle boards come with fins and attachment systems that are designed specifically for the particular brand of paddle board. These nonstandard fins systems will usually get the job done but have some potential drawbacks.
Firstly, if you lose a brand-specific fin or forget to bring it on a trip, you can’t just go to a SUP or surf shop and buy a replacement fin.
In this situation, you can only get a replacement from the manufacturer of the board. Also, if you want to use a different type of fin to adjust the performance of the board or adapt it to the specific paddling conditions, you are limited to whatever fins are provided by that brand, which are often just one size and shape.
Many of them consist of tether and 'tab' system with a velcro or slot connection to the board. This idea seems great in terms of not loosing a fin, though is actually a dangerous hooking hazard below the water and a flawed design.
A proprietary fin system is generally a cost cutting measure. For a universal FCS system the manufacturer may need to pay FCS a license fee to use the box and mechanism, so to save a few dollars many manufacturers use a cheap clone or system. The informed buyer in this instance should take note as it can be indicative of that brand cutting corners elsewhere.
SUP fin systems are mostly derived from surfing. The technical factors have been refined since the first fins were placed on surfboards in the 1930's, leading to an obsessive level of nuance for surfboard shapers.
For most SUP boards this nuance isn't as dramatic since most paddle boards don't require the drive you need from a surfboard down a wave or the level of control. Paddle boards generally have much more volume than a surfboard therefore the effect of fin positioning is more subtle, though the difference in arrangement will be more obvious if paddling boards of similar size and dimension.
A thruster fin setup consists of three equally sized fins, with one of them centered near the tail of the board, and a pair of fins of the same size positioned near the edges of the board, slightly forward of where the center fin is placed or in a equilateral triangular shape.
This is a practical all-purpose setup that avoids the need for a long center fin by distributing the total fin area of the board among the three moderately sized fins. It works particularly well in shallow waters where a long center fin would bottom out and is perfect for casual SUP paddling.
There is a small reduction in tracking and lateral stability when compared with a setup that uses a long center fin, but the 3-Fin thruster setup can be accomplished with either permanently attached or removable fins, and the shallow water advantages of the setup make it a great choice for many paddlers.
A thruster setup on a SUP board works great for surfing as the lower profile results in the back end being a looser. This means wave doesn't grab the larger fin and sweep the board from you while turning.
One long fin in the center fin box is a simple setup that has some performance advantages. With the proper choice of fin for the center box, this can be a very fast and generally stable setup. Having just one fin reduces drag and thereby enhances speed, and the depth of the fin in the water helps with stability by inhibiting side-to-side rocking.
You will mostly find a single center fin box on touring and race boards, though some manufacturers use a single fin configuration on their entire board range.
The drawback to a single fin configuration is less flexibility and stability when you want to explore shallower water. Choosing a shorter fin this instance won't have the support of the side fins so it can be limiting if you want to paddle in different environments of uncertain depth.
One long fin in the center box, along with a pair of shorter side fins is the setup that provides the most tracking and stability. Compared with the single fin setup, the side fins provide additional tracking and resistance to side-to-side rocking.
The addition of side fins also helps the tail of the board resist sideways forces from wind or current. Paddlers will choose a single fin for speed on calm days and add side fins when wind, current, and chop conditions are more demanding.
The 2+1 setup is the most flexible "do anything/go anywhere" setup, as fins can be adjusted to the particulars of your session and the paddling environment. It has the advantages of a single fin design on days when you just want to go fast in deep water, and can be set up with shorter fins in a thruster configuration for exploring water of varying depth.
This is similar to the 3-Fin Thruster setup, but without a center fin. This setup makes for a “loose” board feel, meaning the board has a tendency to turn quickly because the fins act as alternate pivots. This can give a board an agile feel and enhance some surfing maneuvers, while being more difficult with others especially on an inflatable.
The downside is a reduction in tracking and an increase in side-to-side rocking for flatwater paddling. There is less lateral surface area being controlled with the smaller fin array, so the board will have a tendency to keep pivoting slightly to each side and is a little more difficult to keep tracking straight.
There is a lot more to know about specific fin shapes, fin layouts, and performance characteristics, which you can learn about in this detailed article. The type of fin system on the board you buy will determine what your fin options will be after you own the board, so understanding the basic types of fin systems is an important first step to choosing the right paddle board.
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