Resources

This page contains a collection of resources, such as fin layout guides for different types of boards and fin setups. These guides can be freely downloaded to serve as a hardcopy reference.

We start with a Fin Setup Primer, available for download, which should help you better understand fin layout and terminology.

The layout guides provide information on fin positioning for all standard fin layouts. They are not specific to any given board length; they are only intended to serve as a starting point. It is left to the builder to determine their preferred layout.

Various guides also detail the GEARBOX system's fin base and layout options. All are available as downloadable PDF files.

Finally, a new TIPS & TRICKS section provides ideas for improving an installation's strength or quality, or gaining a better understanding of the process. As new ideas arise, they will be added to this section.

Most of the sections on this page are initially collapsed to reduce scrolling. Then, click on the associated section icon or image to expand the content.

Overview

Key Resources

Shortcuts to the most commonly accessed resources.

Fin Primer

This primer offers extensive information about fin setups and the effects of specific changes. It also covers some of the terminology used in these discussions.

Details

Layout Guides

A wide range of fin layout guides are available for download. These cover all of the modern layout styles for both surfboards and kneeboards.

Details

Technical

Technical details are provided for the system. These cover details, such as the base of the fin to correctly fit a GB24 box.

Details

Tips & Tricks

Downloadable GB24 Installation Guide PDF file. The same document is provided with the standard routing system and starter kit.

Details

Fin Primer

A Guide to FIN SETUP and TERMINOLOGY

At best, this is more art than science, but well worth experimenting with!

The beauty of an adjustable fin system is that you can go out and experiment for yourself to verify what effect a change in fin placement can have on a board's overall performance. This primer will use some terminology best explained upfront so that we all speak the same language.

Terminology

fin triangle or cluster

This is the grouping of the fins, whether a thruster, quad, or 2+1; it refers to the entire fin layout.

fin setup

This is the position of the entire fin cluster as a unit, either all forward, all back, spread apart, grouped, etc.

cant angle

Also referred to as fin angle, it is the amount by which the side fins are leaning out from the centerline of the surfboard, bottom up.

toe-in

This is the amount that the front of the fin boxes are pointed in (toed in) from the centerline of the box towards the stringer.

fore 'n' aft

This is the position of the fin in the box forward or backward along the length of the board.

spread fin cluster

This is where all the fins in the cluster are spread as far apart as possible, and side fins all the way forward and center fin back. This generally makes the board stiffer. The fins are spread as far apart as the box adjustment will allow for quads.

tight fin cluster

The opposite of the spread fin cluster, typically side fins back and center fin all the way forward, makes the board looser and more pivotal. For quads, the fins are pushed as close together as the box adjustments allow, with front fins back and back fins all the way forward.

thruster setup

A thruster setup consists of side fins and a center fin, with the most common setup featuring fins all the same height.

quad setup

A quad setup consists of two sets of side fins, with the most common setup featuring a larger set of fins in front of a smaller set. The placement of these two sets relative to each other can vary widely, but our preference is for them to be close together.

reverse quad setup

A reverse quad setup consists of two sets of side fins, with smaller fins in front of a larger set. The placement of these two sets relative to each other can vary widely, but our preference is for them to be close together. This is a term we coined to describe this setup arrangement.

twinzer setup

A twinzer setup consists of two sets of side fins, with small canard-style fins in front of a much larger set. The placement of these two sets relative to each other is typically very tight to allow the canard fin to serve as a transition fin to the larger fin. In addition, the canard fins typically have additional cant built into the base to have more cant than the boxes usually provide.

twin fin setup

A twin fin setup consists of two sets of side fins. The fins are typically fairly large and placed close to the rail and closer to the tail than typical thruster side fins.

5FIN setup

A 5FIN setup is simply a quad setup with the addition of a center box, and this allows the board to be ridden as either a quad or a thruster or with all five fins.

2PLUS1 setup

A 2+1 setup consists of side fins and a much larger center fin, most commonly placed in a regular longboard center box. The side fins are typically much smaller in relationship to the size of the center fin, but the heights can vary.

Fin Setup Traits

spread fin cluster

longer turning arc, which is more common on longer boards or guns

CONDITIONS: larger, faster waves, situations where a gun would more likely be used, more projection

tight fin cluster

shorter turning arc, the typical setup for smaller thrusters

CONDITIONS: wide range, depending on skill and the board's shape

fin cluster forward

looser, shortest arc, less hold

CONDITIONS: pivotal surfing on small to medium waves

fin cluster normal

loose with control, typically the position designed by the shaper

CONDITIONS: versatile wide range of conditions

fin cluster back

more control, more projection, bigger tube/pocket waves

CONDITIONS: once again, this is typical for situations where a gun would be used

more fin cant

looser with less drive, requires more turning to generate speed

CONDITIONS: small to medium surf

less fin cant

stiffer with more drive, bigger, faster hollow surf

CONDITIONS: commonly used in twin fins, guns, or tow-in boards

The above is just a tiny sampling of the more apparent combinations. There are many more in between or with subtle variations. The intent is to provide a little insight into the more general characteristics of fin placement.

The position and cant of the fins are critical and significantly affect a surfboard's performance. The slightest change can sometimes dramatically affect the board, but it is not a magic bullet. Sometimes, the opposite effect can occur. Fin setup is just one piece in a complex dynamic system of shapes and curves that make up a surfboard.

Each board is different, as is each surfer, so any changes could have various results depending on the board and the surfer!

The information provided above applies to a 2+1 fin setup, except, in that type of setup, the size of the center fin has a more heavily weighted effect on the cluster. The smaller the center fin, the more it will perform like a thruster. Therefore, the placement of the center fin will be the more controlling aspect of the performance of a 2+1 setup.

Of course, other factors can affect fin setup, the size and shape of the fin, and even the foiling of the fin, as well as whether all of the fins in the cluster are the same. However, we believe the beauty of an adjustable system is that it allows the surfer to experiment for themselves to determine what works for them and to help them learn the significance of being able to adjust the fin setup on a surfboard.

Our system was designed with built-in adjustability, making hands-on experimentation with fin adjustment easier.

Illustrated Terms

The renderings in this section show illustrations for some of the terms used in the fin setup discussion. Hopefully, these will provide a visual guide to some of the terminologies.

FIN CLUSTER

Shows what is referred to as a fin cluster, the combination of all the fins in the layout.

CLUSTER REAR VIEW

Another view of the fin cluster from the rear of the board shows the cant angles of the fins in the cluster. This is the most common view used to refer to the left and right fins when talking about fins.

CANT ANGLE

Shows how the cant angle is measured. The cant angle is built into the box with the GB24 fin system. The correct cant angle needs to be selected before installation.

TOE-IN

The toe-in of the boxes is another critical value, shown in this drawing. This is the distance the boxes are pointed towards the stringer from the box centerline. This can vary from the front to the back fins in quad setups.

SPREAD FIN CLUSTER

A spread fin cluster is where the fins are spread as far apart as possible. For a thruster, the side fins are as far forward as possible, and the center fin is as far back as possible. For quads, the front fins are as far forward as possible, and the back fins are as far back as possible.

TIGHT FIN CLUSTER

A tight fin cluster is where the fins are pushed as close together as possible. For a thruster, the side fins are as far back as possible and the center fin as far forward as possible. For quads, the front fins are as far back as possible, and the back fins are as far forward as possible.

Fin Primer

Download

Layout Guides

Several fin layout options cover all the most common fin setups. To facilitate usage, downloadable PDF files are provided.

The provided layout guides show the GEARBOX box being used, but these guides can be used with any fin system, as the measurements apply to any of them.

Twinzer Layout

Download

Quad Layout

Download

5FIN Layout

Download

Thruster Layout

Download

Twin Layout

Download

2PLUS1 Layout

Download

KB Twinzer Layout

Download

KB Quad Layout

Download

KB 5FIN Layout

Download

KB Thruster Layout

Download

Technical Details

Ancillary technical details about the system.

These are some additional technical details related to the system that might prove helpful.

Standard Base

Download

Keel Fin Base

Download

Keel Adjustment

Download

Install Guides

Standard Install Guide

Download

1ROUT Install Guide

Download

Tips & Tricks

Valuable lessons we have acquired that may enhance your utilization of the system.

Although the STANDARD and 1ROUT installations are successful, techniques or alternative approaches can still be employed to enhance the installation process.

We will share some of these insights here, as they may prove beneficial either as a supplementary method to the standard installation or as a revised approach.

It is important to note that, as with any installation methodology, it is highly recommended that a few test installations be conducted before implementing any changes. This will help you better understand the process and enhance your confidence in the decision.

We will also delve into greater detail regarding the setting of the router bit depth to address deep concaves.

If you have any questions, please do not hesitate to contact us. We are here to assist you.

Pre-glue Boxes

Pre-gluing the boxes can simplify the installation process.

The illustration shows how the box would sit in the cavity during a standard installation. Ideally, it should be slightly below the bottom of the board. More on this later!

The motive for pre-gluing the boxes into the cavity is twofold. First, it is a lot less stressful and gives you the time to get everything set up perfectly (for those that prefer to have a fin in the box to check the cant angle, it makes that more accessible). Second, it means a coat of resin can be applied over the top of the cover, filling in the hex grooves and creating small curved ramps against the dam and outer edge of the cavity. See the detailed image below.

To pre-glue the boxes, the routed cavity is covered with resin, as is the underside of the box. Then insert the box into the cavity and allow any excess resin to squeeze out. Next, using a brush, spread the resin over the cover and the lower edge of the dam. Due to the nature of the resin, it will create a small fillet at the dam and the outer edge of the cavity. This makes it much easier for the cloth to drape over the box. This is one of the main reasons the box should sit slightly below the lip of the cavity.

The illustrations above show how this works step-by-step.

Another reason to set the box slightly below the cavity edge is that this technique allows the bottom lamination and reinforcement layers to drape more easily over the box cover.

This is important because if the box were flush with the bottom of the board, there would be a greater risk of sanding through the lamination or, at the very least, grinding away the second reinforcement layer. By lowering the box, the cloth ends up slightly below the bottom of the board, making it much harder to sand through the layers.

Once the boxes have been glued in, lamination can proceed, or if it is a post-lam install, the reinforcement layers can be applied. The gelled resin used during the gluing process makes pressing the cloth tight against the box very easy, as the resin will still be tacky. This will help hold the fabric in place while laminating.

It is essential always to place the SECOND reinforcement layer ON TOP of the bottom (or first) layer. The reason is that sanding through the bottom layer is less risky, which would be very easy at the edges of the reinforcement layer if it were underneath the primary layer.

Given the dam’s shape, this process ensures a clean installation with little to no air around the base.

Sectional view of the box in the routed cavity

Box glued is showing the resin fillets

The first primary layer of glass is applied over the box

The second layer of glass applied

A hot coat is applied over the glass

Finished installation with the board sanded down

Deep Concave Installs

When installing boxes on a board with deep concaves, an extra precaution must be taken to ensure the boxes are installed cleanly.

When the router jig is placed on a deep concave, it can bridge the concave, as shown in the illustrations below. When this happens, the box will not sit flush.

For this reason, the depth will need to be deeper by the amount of bridging. The aim is to get the box to sit slightly below the lowest part of the concave. The depth gauge will not provide enough depth due to the concave.

Generally, working with normal concaves takes about an extra 1/32" / 0.5 mm of additional depth.

Always do a test run to check that there is enough depth.

The illustrations below show what things will look like with a standard rout and the compensated-depth version.

Router jig sitting on a deep concave

When installing a board with deep double concaves, extra precautions must be taken to ensure the boxes are installed cleanly.

End view shows how the router jig spans the concave

When the base jig is placed on a deep concave, it can bridge the concave, as shown in the illustration above. When this happens and the STANDARD router depth is utilized, the box will not sit flush.

After routing with the standard depth, the box would end up sitting slightly above the lip of the cavity

Normal rout would leave the box sitting above the lip of the cavity

For this reason, the depth gauge provides a CONCAVE depth that sets the cavity deeper. The aim is to get the box to sit slightly below the lowest part of the concave. In some cases, the depth gauge might not provide enough depth due to the severity of the concave. Always do a test run to check that there is enough depth.

Box set slightly below the lowest lip of the cavity by utilizing a deeper rout

Using the CONCAVE depth on the gauge the box should end up slightly below the lowest lip of the concave. As shown in the above illustration.

Final routed cavity

GEARBOX - An advanced removable surfboard fin system.

GEARBOX Surf has locations in Australia and Hawai'i (USA). Contact information is provided here, but the preferred method is to use the contact form on this site.

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GEARBOX Surf Hawai'i
Hanalei, Kauai

+1 808 639 5303

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+61 243 399 580

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