One of the most fun things about snorkeling or scuba diving is the relative ease with which we are able to propel ourselves through the water thanks to equipment. Often, I have people ask how much faster they can swim with fins on.
For some people, the reason for this question is simple curiosity. When you swim with fins, you feel much faster.
But how much faster are you really?
For others who have not yet engaged in watersports, the question may be due to concerns about their own swimming ability. So how much faster can you move with fins?
The typical swimmer will add 30-40% to their swimming speed when wearing fins. As with many things, the answer here is variable depending upon your kicking style.
Let’s take a look at how fins work, how they change our ability under the water, some interesting research into their effectiveness, and different types of fins.
How Do Fins Work to Improve Speed?
To understand how fins work, we first must discuss the mechanics of swimming a bit. After all, it was mechanics that led Louis de Corlieu, a Lieutenant Commander in the French Navy to invent fins in the early 1900s.
He took his inspiration from the webbed feet of frogs and ducks and sought to develop something that would give humans the same benefits.
Humans have very strong legs. This is not surprising as we walk upright. However, we are not naturally very fast swimmers.
Why is that?
Basically, our feet are not designed for swimming. Despite our strong legs, we lack sufficient surface area and flexibility in our feet to generate propulsion.
Let’s think about how water functions. Think about Newton’s Third Law that any force is met with an equal and opposite force.
When we push against water, water pushes back. Increasing the surface area of our feet (by wearing fins) amplifies our force against the water, generating a greater force back from the water. This propels us faster.
This is why when you kick with fins on, you boost along the water with relative ease.
What Does Research Show about Performance with Fins?
Most of the research into performance of fins actually comes from the sport of swimming (like, Olympic swimming). This may be surprising but swimmers sometimes train with swim fins in order to improve ankle and leg strength.
They have found that training with fins makes people better swimmers when not wearing them.
There are a number of interesting things that have been found. First, while specific performance varies on an individual to individual basis, fins tend to make people 30-40% faster in the water.
Additionally, wearing fins greatly decreases kick frequency. This is due to being able to propel yourself more with each kick due to the increased surface area. For most people, kick frequency with fins decreases by 40%.
Finally, wearing fins allows conservation of energy, with a reduced energy cost of roughly 40%.
This is the most interesting finding for scuba divers as the goal is not speed but reduction of energy expenditure, which leads to conservation of air.
What Types of Fins are Fastest?
In the scuba diving community, there can be fairly significant debates regarding the best types of fins to wear with divers having their own preferences. So let’s take a look into what fins are best. Here, we are not talking about brands but rather types.
The first thing to consider is whether shorter fins or longer fins are more effective at speed.
You may be tempted to think that the answer is longer fins because they provide greater surface area. However, in addition to thrust with each kick, we must also consider the ability to kick repetitively.
Long fins are floppy and take longer to complete a kick cycle. By contrast, short fins allow someone to kick at a much higher rate for a longer period of time. As such, short fins actually end up being faster than long fins.
Another newer type of fin is the split fin. Split fins are designed with a partial slit in the middle in order to mimic a fish’s tail. People wearing split fins often feel able to swim with less effort, leading them to think they are swimming faster.
However, split fins will not increase someone’s maximum speed because longer, harder kicks decrease the efficiency of their design. Thus, split fins improve the level of effort needed but not top speed.
Fins improve swimming ability by increasing the surface area of our feet, allowing us to propel more easily through the water. They improve swimming speed by 30-40%.
However, the primary purpose of fins for scuba divers is efficiency. A diver can swim with 40% less energy consumption when wearing fins, making them a staple of the underwater environment.
When considering speed, there are other factors at play aside from surface area including fin design.
Thus, short fins are typically faster than long fins because they allow for more frequent kick cycles while split fins will not increase a diver’s top speed as their design becomes inefficient with excessive force.