A lot of research went into buying my first handboard for bodysurfing. I noticed the bottom contour of some boards were curved while others were flat, which made me wonder if this made a difference.

What is the difference between concave and flat handboards? Concave handboards are curved inwards to help bodysurfers maneuver fast steep shore breaks. Flat handboards feature a straight, level underside to help bodysurfer acquire more speed and distance when riding small, rolling waves.

Let’s take a deeper look at the benefits and drawbacks of both. The rest of this post will inform you why there is a need for the different designs and help you determine which style of handboard is right for you.

handboard design 101

If you are like me, then you are probably wondering why the bottom of a handboard even needs this much attention. I didn’t think the shape of the underside made much of a difference until I did some research and experienced it firsthand.

The science that goes into creating the underside of a handboard can be very complex and is greatly misunderstood.

Your handboard is constantly changing speed and direction while riding waves. The ocean is constantly changing shape in addition to speed and direction. The combination of these to changing factors becomes a highly dynamic variable equation that I honestly do not know how to calculate. There are so many different theories, opinions, and formulas out there that it can get confusing.

Here is my attempt to keep things simple. From what I understand, altering the bottom surface manipulates the flow of water underneath a handboard in a way that enhances the rider’s performance. This feature significantly impacts the interaction between you and the type of wave you are riding. 

what is concave?

Still not sure what concave means? It’s a line or surface that curves inward. Think of a semi-circle or if you were to cut an ellipse in half. It is arched inwards or upwards compared to the outer edges or rail line. Take a look at the images below. It compares a concave line to a flat line.

advantages of a concave handboard

Why use a concave handboard? There are some significant benefits to using a board designed this way, especially for steep shore break. Below I have listed a few advantages to consider if you are thinking about getting one.

• increased wave grip – The concavity of the hand board acts like a suction cup on the surface of the wave. This feature allows your rail to “bite” the wave giving you more hold when riding a steep face. It will help you carve up the wave like a pro!
• improved control & stability – Riding gnarly waves is very challenging. You are constantly trying to keep yourself stable.  Using a concave handboard will help you stay in control and increase your stability even during a vertical drop.
• increased lift & drive – The curve under your board will contain water flow extremely well and quickly push it out the backside. Concavity also slightly increases the surface area of the board. This will enhance the lift, reduce drag, and increase acceleration while you ride.

disadvantages of concave handboard

There are a few drawbacks to consider regarding a concave handboard. I have listed some that stood out to me below.

• not for beginners – This is considered a disadvantage if you are a beginner. I only recommend purchasing a board like the Bula if you are an experienced bodysurfer.
• sticky rail turns – Performing sharp turns and maneuverability can be pretty challenging with this type of board. I recommend sticking to lighter turns if using a deep concave board.
• not good for chop – Another downside to this type of board is its performance in choppy waters. You will be better off using it in smoother conditions.
• more expensive – Typically concave boards are more expensive. Extra time and precision are needed to create the perfect shape. Therefore it requires more money to make.

shallow concave vs deep concave

The depth of a handboard’s concave bottom impacts wave-riding performance. Some handboards, like the Bula, have a very deep concave structure while others like the Wedge have a very shallow concave structure.

A deeper concave bottom provides a better grip on a steep wave face. This is why a concave board is perfect for a steep shore break.

You will be able to carve up these types of waves. You will get more tube grip than a shallow concave board. However, a deep concave tends to magnify its own effects. This is when a less concave board comes in handy.

If you ride waves that are not as towering and prefer to perform sharp turns and cutbacks, you will need a shallow concave handboard. It will still provide excellent grip while giving you the freedom to do sharp turns.

Shallow concave handboards eliminate the “stickiness” you would encounter with a deeper concavity. Also, shallow concave handboards are much better suited for choppier waters.

what is flat?

I’m sure you know what a flat bottom is. In case you need clarification it is simply a flat, straight surface. There are no concave or convex contours. It is flat from edge to edge.

advantages of flat handboards

Even though concave handboards have clear advantages, flatter handboards also have some great benefits. I have listed a few of them below to consider.

• increased speed & aqua dynamics – Want to haul some a** down the line? Flat bottom handboards like the Phishboard gives you optimal planing capability. This enables you to cruise much quicker than other boards on the water. This type of bottom design moves water behind the board faster, which accounts for the increased speed.
• great for small waves – Flatter handboards will perform very well in small, mushy waves or choppy water.
• decreased drag – A flat handboard experiences less drag. Concave boards can have a tendency to get stuck and experience drag on the edges. Flat boards will not have this issue.
• more affordable – Typically, less time and less money are needed to construct a flat bottom board. Manufacturers do not need to shape it as precisely as a concave board.

disadvantages of flat handboards

Here are some clear disadvantages of flat handboards that you should be aware of.

• minimal hold – Flat boards do not have much grip at all. This will cause you to easily skim off the wave face if you are riding one that is steep.
• increased risk riding bigger waves – If the surf you are riding is fairly large and you have flat board, you could injure yourself and other surfers if you lose control. Since flat handboards offer minimal grip, it will be challenging to surf larger waves. Going fast in choppy water can generate intense vibrations and bouncing since it is not designed to cut through waves or vent the water.
• no lift – A flat-bottom design offers no increase in lift. This can bog you down at lower speeds.

concave vs flat board matrix

Here is a simple little chart I put together to help you know when to use certain boards. It should be helpful when you decide to purchase your next handboard.

wave type	handboard style
steep shore break	concave
tall, smooth waves	concave
small waves	shallow concave/flat

*General Rule of Thumb: 

The steeper the wave the more concave your handboard should be to help you maintain control as you ride the barrel.

On the other hand, if you are riding small waves in choppy water then make sure to stick with a less concave board such as the Grom, which provides excellent buoyancy for these conditions.