Why is My Surfboard Sinking?

surfboard sinking

This particular question can be difficult to completely determine.  There might be a combination of reasons for why a surfboard would be sinking.

Some reasons might center around damages sustained to the board itself and subsequent waterlogging.  While others potentially focus on board size relative to body size, positioning, or technique and performance.

Throughout this article, we will attempt to explain how each of these explanations might fit into your situation.  This will help you correct the problems so you can get back to surfing as soon as possible.

1. Waterlogged Surfboard

When cracks or smashed portions of the surfboard are introduced to the salt water, it penetrates the board and the foam absorbs water. Depending on the size of the gash, this onset of water absorption can happen rapidly or slowly over time.

Regardless, if the damage is not repaired, water will be sucked into the foam. Out of the currently utilized foams for blanks, EPS foam or Expanding Polystyrene foam absorbs water more readily.

If you’ve been neglecting a surfboard repair for some time then it might be adding unnecessary weight.  This decreases its buoyant force when you try to get up and stand on it. This one is pretty straight forward.

How to Tell if a Surfboard is Waterlogged

One method to find out if your surfboard is waterlogged is by putting your mouth to the opening where the damage occurred. Be careful when doing so, as the fiberglass can be very sharp and jagged. Gently try to suck out any water.

If the board is so waterlogged that it’s causing you to sink upon lying or standing on it, you’ll immediately be able to suck out some water.

How to Dry a Waterlogged Surfboard

In the event that it is truly waterlogged, you’ll need to let the surfboard sit in a warm, dry place for a good while. Drying times will vary based on the severity of the saturation.

surfboard is drying

There is no way to definitely determine whether you’ve gotten all of the water out, but the more time in a warm and dry place, the better your odds. Once you’ve given the board enough time, you will definitely want to make sure to get the repair done so you don’t rehash the problem.

2. Surfboard Size

Are you trying to surf on a board that is dramatically smaller than you should? While not necessarily an easy question to answer, there are some guidelines behind it and a little bit of science to help along the way.

variety of surfboard sizes

One of the main factors in making this determination is the volume of the board which is calculated by the length of the board multiplied by the width and then multiplied again by the height or thickness (L x W x H). This will provide the overall volume of the surfboard.

In modern times, these measurements and overall volume are usually noted within product descriptions, and sometimes, on the board itself.

Surfboard Volume

Some average figures for the volume of a shortboard, 7-foot fun size board, and longboards are:

But why is the volume of the surfboard even important?

It’s important because it directly affects the buoyant force that keeps you afloat. It’s the force that pushes up on an object submerged in a Newtonian liquid. I will try to keep the physics lesson short, though. Without having to draw diagrams, we can skip to what’s really important.

Surfboard Volume to Weight Ratio

That is the volume to weight ratio. Simply take your weight and divide by the volume to get a number. I know, this number seems very arbitrary. But here are some useful guidelines based on the number that is calculated.

For instance, a good ratio for starting out with beginners is 2.0 pounds per liter. Basically, as the ratio nears a one to one correlation, your weight is equaling the weight of the board and thus allowing for a more prominent buoyant force.

As the number increases, more than likely your skill level has increased, and you now possess the technique to surf smaller boards. Kelly Slater is listed at 160 pounds and surfs boards around a volume of 24.0 liters per pound. Thus, his ratio is 6.67.

Good Judgement

And like I’ve said, a lot of the time, it’s not necessarily the weight of the surfer that is preventing them from being able to stay afloat. Many times, it’s simply the technique and skill level.

Regardless, just take this portion of the article as a guide because it is true that you can be too large for a surfboard and thus, are causing it to sink. Think of a large football player trying to ride a child’s surfboard.

While I won’t be the one to say that they personally couldn’t do it, it just doesn’t seem plausible on paper. It’s not always the case, though so try and use your best judgment.

3. Position and Technique

As I just mentioned, the overall weight of a person might not be the determining factor that is resulting in your surfboard sinking. The position you take on the board, in addition to, your technique pre-wave and on the wave has a large effect, too.

surfboard technique and skill performed by a surfer

For example, if surfing on a shorter board, you simply cannot stand too far back or too far forward. The weight needs to be distributed evenly. Doing either of these will result in the board sinking, as is with the latter case or nosediving in the former.

Not only does it prevent you from riding the wave, but it will cause the board to sink. If this is something that you have caught yourself doing, it might very well be the reason that your surfboard is sinking.

Work on your technique and weight distribution to correct these issues. Obviously, this type of problem isn’t really present with longboards as the weight and buoyancy counteract any positional problems. Think about hanging ten.

Surfboard Paddling

Another position issue that might be causing your surfboard to sink involves your position on the board and paddling. Every board is different and has a sweet spot, but ultimately, you want to have your torso near the center.

Positioning yourself too far towards the nose will result in a nosedive or what is known as ‘pearling’. If you’re too far back, you’re going to slow down the surfboard and create unnecessary drag. No matter how hard you paddle, it’s going to be near to impossible to catch the wave.

This could be a cause for your board sinking. If you think this is the case, reposition your body towards the center and try to find the sweet spot. It might take some time, but eventually, you’ll recognize mistakes and be able to correct your form.

Surfboard Sinking Summary

Whether your surfboard is waterlogged, the volume to body weight ratio is not indicative of your talent level, or your position and technique are preventing buoyancy, there are ways to correct these issues.

If you have damage, check for water content within the foam of the board. If you believe you might be on a surfboard that’s too small, do some basic volume to weight calculations and objectively evaluate your talent levels.

And if you seem to stop while riding a wave or can’t seem to catch it, step back and look at your technique and positioning. It very well may be the problem.

Compare and Review Surfboards

In review, you should calculate your surfboard volume to weight ratio to get the appropriate surfboard volume ratio. The volume of the surfboard can be found by using this formula (L x W x H). 

L = Length of the board

W = Width of the board

H = Height of the board

All these measurements can determine what the right surfboard is for your skillset and weight. As a result, your surfboard won’t sink once you get into the ocean. Take a look and compare some surfboards.


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