The Physics of Drag

In 2008, twenty-five world records fell in a single pool, and the reason was not the swimmers. This week’s letter is about the force nobody trains against.

Three-minute read · Allocra

The Water Cube

It’s August 2008, in Beijing, China. The world had witnessed one of the greatest opening ceremonies to any sporting event and Usain Bolt would go on to win three gold medals. Sandwiched between these, something seemingly impossible happened at these Olympics. In the ‘Water Cube’ Aquatics Centre, an unprecedented 25 world records were set.

What had happened in the four years since the Athens games? Were there new training regimes, dietary supplements, different water?

No, none of these, but different water comes closer than you might think. Not different water; but a means to ensure the water responds differently to the swimmers. Hydrodynamics.

The Suit

Until then, the philosophy of competitive swimming was largely based on generating more power. Swimmers trained to pull more water, kick harder, and build more muscle. Eventually, sports scientists and engineers from NASA took a different look at the problem. Water is roughly 800 times denser than air. As most of us are reminded each summer, moving fast through a medium that thick is incredibly tiring.

The solution? Stop worrying about power and start reducing drag.

The result was the Speedo LZR Racer, a polyurethane suit that compressed the swimmer’s body into a hyper-streamlined tube, trapped air for buoyancy, and repelled water. Swimmers didn’t get stronger; they just reduced the water pulling them backward. The suit ended up being too effective. It was ultimately banned from competition.

The Drag

So why, you may ask, am I stopping to write about a swim suit?

When we manage our own investment portfolios, we spend almost all our mental energy trying to “generate power.” We search the market for the best yields, try to perfectly time our entries, and agonise over which sectors will outperform the market next year. We spend massive amounts of energy trying to swim just that little bit faster.

Yet, we rarely look at the drag.

In investing, drag is the silent friction pulling you backward. It’s the ongoing charges of the funds you hold. It’s the subtle FX spreads applied by platforms. It’s the friction of tax inefficiencies as you rebalance. Over a thirty-year investing horizon, these tiny percentages don’t just add up; they compound, creating a massive hydrodynamic drag on your wealth.

The Long View

You don’t always need to be a stock-picking genius, generating massive alpha, to build long-term wealth. Sometimes, the most effective strategy is incredibly simple.

Streamline your portfolio, aggressively reduce your downstream costs, and let compounding do the heavy lifting without the friction.