Surfing Explained: Ep3 What is Surfboard Volume

In Episode 3 of Surf Simply's animated exploration of surf science, we explain how the surfboards volume impacts which waves you can catch, and your success at catching those waves.

This episode was written by Surf Simply Coaching Director Harry Knight, and animated and edited by Surf Simply Coach Will Forster.

Season 1 will cover 4 episodes over the next 4 weeks:
Ep1: Understanding Speed and Grip
Ep2: Generating Speed and Grip
Ep3: What is Surfboard Volume
Ep4: Using an Online Volume to Weight Calculator

Transcript:

In this weeks episode, we’re going to explore surfboard volume, and what it actually means to us.

What is Volume?
The volume of your board is a measurement of the total amount of space that your board occupies. If your board were a perfect cube, then a simple length x width x height calculation would be all we’d need. However, as your board is full of curves and concaves, the whole thing is a little more complicated. In the past, the only way of knowing was to dunk your board in a bath, and see how much water was displaced and this is why we normally measure surfboard volume in liters rather than Cubic Inches.

Nowadays with most boards designed using computer software, it’s easy to calculate the volume of a finished board, and most of the leading brands display the volume of their boards both on their websites, and increasingly on the surfboard itself. As some ballpark figures, an average shortboard would probably be around 25-35 Litres, while a 7’ midlength would be between 40-50L. A longboard might go from 60-100L, and a SUP could easily top 250L.

Why is Volume Important?
Volume matters because it gives us a realistic idea of how big our boards are. Ever since the “Retro Revolution” of the early 2000s, people have been riding an increasingly diverse range of surfboards, and now the standard 3 dimensions (length, width and thickness) don’t give us enough information to decide if a board will work for us or not, and you can shape 3 boards with the same 3 dimensions, that look and surf very differently.

In reality, the thing that volume really tells us is how “buoyant” the surfboard will be, and therefore how well the board will float you in the water. This matters because the higher a board floats you out of the water, the less drag your body will create as you paddle, and so the faster you’ll be able to move. The faster you can paddle, the more waves you can catch, and the less steep those waves need to be in order to catch them. However, the volume of the board is only half the equation, the other part is the weight of the surfer, as a heavier surfer will need more volume to create the same buoyancy.
This brings us to the important ratio between a surfer’s weight in Kilograms and a surfboard’s volume in Litres, which we’ve decided to describe as a percentage, as we think this is the most intuitive way to express these ratios. As an example, an 80kg surfer riding on a 40L board would have a ratio of 50%, while a 40kg surfer on the same board would have a ratio of 100%.

What do I do with this Information?
There are no hard and fast rules when it comes to choosing a surfboard. Many people have learnt from day one on tiny shortboards, while others have purposely chosen to only surf 9ft+ longboards, and individuals from both groups have gone on to be world champions. There will always be a huge amount of subjectivity in the final decision, and a board that one person loves may not click with another.

With all that said, you should not view any size of board as a “goal”, you should view a maneuver as a goal. A misconception that has plagued surfing for decades is the idea that a smaller board = a better surfer, and too many people view the size of their board, as a badge of their ability in the water. The problem is that while a smaller board is, in theory, easier to turn than a bigger one, it is also easier to force bad technique on, which long term will hold you back far more than those extra 10 liters ever could.

A board that is too small will paddle slow, catch waves late, and bog down in turns. A board that is too big on the other hand has only one downside; if your technique is poor, you can’t cheat and torque the board round with your upper body.

By using this information as a starting point along with a volume to weight calculator, you will be able to choose a board to help you work on the techniques to progress.

In next weeks episode, we will be exploring how to get the most from the Surf Simply Volume to Weight online calculator.

[uluwatu]

You guys are doing an amazing job. Thank you. I've been surfing for 40 years and just now I'm beginning to learn and understand what goes behind the curtains on the sport I'm most passionate about. Thanks

[MNathan]

Pretty accurate Volume calculator: [Length (in inches) X Width X Thickness] divided by 106.5

[lukehunter]

These are the best informational surfing videos out there. Period

[joacole]

Mate, such great content you've shared, keep these series coming, it is a clear representation of adding value, my 1 year old niece could understand this, very well explained, congrats !!

[dennisgordon]

This is really nicely done. The narration the animation and the thought process of how to show whats being said. Kudos

[timothyom]

Amazing as always! Please keep the science of surfing updates coming! It’s fascinating and very helpful.

[stephengreenwood]

Thank you for these, I love theory craft and understanding what physics are involved. This lets me visualize what's happening, understand why the board dynamics and kinetics with water moving under it this allowing me to adjust my learning progressively rather than ” you will just know when you know ” what kind of bollocks learning is that?!!

[nicolaspohl]

Awesome video. Is there a recommended ratio for a shortboard?

[markk]

Great series. My question is how the volume of the board affects its behaviour when it is planing. The buoyant force depends only on the material below the waterline, and when planing, that is the lower half or third of the board. So the volume of material above the waterline should not affect the board's performance once the board is up and planing. I would be very interested in your take on this.

[ULiel]

Great series of videos. I do think there is a problem though with the volume criteria in surfboards as they can be made from different materials (PU, EPS, wood etc..) with different densities (hence "buoyancies") and with varying types and amounts of glassing.
So, as you explain, what we really want to know is how buoyant the board is, specifically compared to the surfer's weight. Maybe a better, alternative criteria for example is that of average overall density of the board or graph of board percent submerged vs. surfer's weight.

[surfcompanions]

amazing series! Keep going! Great idea!

[nirisheregaming]

Great video! I wonder though what does volume focused on different parts of the board mean... For example more volume in the Lower part of the shortboard

[boltup]

People think they can't turn longboards because they're too big. Then they drop down to a fish because they think it will be easier to turn. No. They can't turn them because they don't get their back foot over the fins. They try to turn from the middle of the board swinging their arms and "looking where you want to go".

[jasontroy]

Volume is only a general guide...other factors are surface area in the rear 2/3rds as well as overall rocker

[YannickMiro]

Epic, Love this series, keep them coming!
Thanks
Yannick

[inigodeaustria]

Thank you so much for what you do!! God bless

[zuyah]

Awesome, supporting comments under every video!🙌

[krusher]

It would be interesting/educational the hear the physics explained (as its a popular miss conception) that a 5kg 30L eps/epoxy board isnt more buoyant than a 5kg 30L PU board.

[muhamadizzaruddin]

My height is 175cm
My weight around 80kg
Can you suggest my shortboard size???
🙏🙏🙏

[Bballbunny]

Thanks for the video - does your volume:weight calculator apply to foam surfboards?

I'm 65kg, ~late level 2, looking at a 48L foamie - i'm going to assume this has naturally got more bouyancy and therefore is appropriate despite it not matching my level on the graph.