How Cord Length Affects Your Tethered Swimming Experience

Cord length is the most important configuration decision in a tether system, and it's also the one people are most uncertain about. The right cord makes tethered swimming feel natural and appropriately challenging. The wrong one leaves you either cramped near the anchor or swimming with slack in the line and no meaningful resistance. Here's how it actually works.

What the Cord Is Doing

A Swim Tether stretch cord is an elastic cord — it stores energy as it elongates and returns that energy as resistance pulling you back toward the anchor. When you're swimming, the cord is always under some degree of tension. The amount of tension at any point depends on how far you've displaced from the anchor, which depends on cord length, pool length, and how hard you're swimming.

At rest — floating in place without swimming effort — the cord should be taut but not pulling hard. As you begin swimming, the cord stretches further and resistance builds. At peak effort, the cord is near full extension and pulling back hardest. This progressive resistance profile is what makes tethered swimming self-regulating: you can't overload yourself, but you also can't under-challenge yourself without backing off your effort.

How Pool Length Determines Cord Length

The cord length you need is primarily determined by the length of your pool or swim spa — specifically, the distance between where the base is installed and the far end of your swimming space. Swim Tether cords are available in lengths from 4.5 feet to 20 feet, and the kit configurator calculates the right length for your setup based on your pool length and pole selection.

The calculation accounts for the distance from the base to the water's edge, the height of the pole, and the geometry of the cord running from the pole tip down to your belt. The goal is a cord that reaches near-peak tension when you're swimming at the far end of your available space — fully extended but not so stretched that the cord is straining or that you're pressed against the far wall.

If your base is set further back from the water's edge than the standard 6–8 inches, you'll need a longer cord to compensate for that distance. The configurator accounts for this when you enter your pool length.

What Happens With the Wrong Cord Length

A cord that's too short for your pool keeps you positioned close to the anchor point. You're swimming against near-peak resistance all the time, with very little range of motion. For some high-intensity interval training this can be intentional, but as a general training setup it's fatiguing quickly and limits stroke development. It can also feel jerky — you're pulled back before you've had a chance to generate momentum.

A cord that's too long for your pool allows too much travel before meaningful resistance builds. In a short swim spa with a long cord, you might reach the far wall before the cord has loaded up at all — which defeats the purpose. In a longer pool, a cord that's slightly long isn't catastrophic, but you'll spend a portion of each stroke cycle swimming with slack, which breaks the continuous resistance feel that makes tethered training effective.

Cord Length and Training Goals

Within the range appropriate for your pool length, you can also use cord length to bias your training toward different goals. A shorter cord (within the appropriate range) creates higher resistance and less travel — better for power development, sprint intervals, and strength-focused work. A longer cord creates more travel distance with a lower base resistance — better for endurance sets, technique work, and building aerobic base.

Most swimmers start with the cord length the configurator recommends for their pool and adjust from there based on feel. Extra cords are available individually if you want to experiment with different lengths for different training blocks.

Cord Lengths Available

Swim Tether cords are available in 4.5, 6, 8, 10, 12, 14, 16, 18, and 20 foot lengths. Custom lengths are available for setups that fall outside the standard range — for example, a base mounted significantly further from the pool edge, or a very long pool where even a 20-foot cord doesn't reach full tension.

The Simplest Way to Get It Right

Enter your pool or spa length into the kit configurator and let it calculate the recommended cord length for your pole selection and base position. It's the fastest way to get a setup that works correctly from the first swim.

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