Why Floating Covers Blow Away — and How Ballast Fixes It

Floating covers earn their keep by being light and easy to deploy. But that same lightness is their weakness on exposed sites: wind.

The physics of wind uplift

Wind moving across a water surface exerts both drag and lift on anything floating there. For a light cover element, the aerodynamic forces can exceed its weight, so the wind:

• Lifts individual elements off the surface, and
• Pushes and piles them toward the downwind shore, opening gaps and exposing the water again.

The lighter the cover and the more exposed the site, the worse this gets. A cover that performs well on a sheltered pond can underperform on a windswept reservoir.

The fix is mass — supplied by the water itself

The straightforward way to resist wind is to make each element heavier. The elegant way is to make it heavier using the water it’s already floating on.

That is what Armor Ball® AQUA does. Each ball self-fills with water ballast, increasing its mass from about 50 g dry to roughly 275 g. The heavier balls resist uplift and displacement, raising the cover’s wind rating from the standard 35 MPH to 75 MPH (120 km/h) — and they do it with:

• No pumps
• No anchors or cables
• No liner penetration

There is nothing extra to engineer into the basin and nothing mechanical to maintain. The ballast is free, and it drains back out if a ball is ever removed.

Choosing the right wind rating

• Sheltered to moderately exposed sites: standard Armor Ball® (35 MPH) is the lowest-cost, easiest-to-deploy option.
• More exposed sites: Armor Ball® AQUA (75 MPH).
• High-exposure or maximum-coverage sites: AWTT’s range extends to 130+ MPH with covers such as Hexprotect® AQUA / Rhombo Hexoshield®.

Not sure where your site falls? Request a wind assessment and we’ll recommend a cover.

Learn more: Armor Ball® AQUA · How it works · Floating cover types compared