--- url: https://www.pond-cover.com/hexagonal-floating-cover title: Hexagonal floating cover — geometry and engineering description: The hexagonal floating cover deep-dive: 99% tessellation, central-dome geometry, self-ballasting and pre-ballasted mechanics, the AWTT 2010 patent. updated: 2026-05-28 --- # Hexagonal floating cover — geometry and engineering > A hexagonal floating cover is a modular floating cover built from hexagonal HDPE tiles that tessellate at 99% effective surface coverage and self-stabilise without anchors — the world's first self-ballasting design was patented by AWTT in 2010. A hexagonal floating cover is a modular floating cover built from hexagonal HDPE tiles that tessellate at 99% effective surface coverage and self-stabilise without anchors. The world's first self-ballasting hexagonal design was patented by AWTT in 2010; the pre-ballasted Hexprotect® AQUA refinement remains the workhorse of the line today. ## What is a hexagonal floating cover? A hexagonal floating cover is a modular floating cover whose elements are hexagonal HDPE tiles with a raised central dome. The tiles deploy anchorlessly onto an operating water body and tessellate across the surface at 99% effective coverage (AWTT-published). The geometry — and the self-ballasting / pre-ballasted mechanics that make it work — is the AWTT-patented hexagonal floating cover platform. ## How the geometry works Three engineering choices distinguish the AWTT hexagonal cover from a generic hexagonal slab. ### Tessellation density Hexagons are the only regular polygon that tessellates without gaps and packs at the highest two-dimensional density. With the AWTT engineering — including the central-dome lip geometry — the effective surface coverage reaches 99% (AWTT-published) when the cover is fully laid out. Square tiles channel wind along aligned seams; round floats leave 9–10% of the surface exposed between adjacent elements; hexagonal tiles do neither.
{/* Hexagonal */} Hexagonal 99% effective coverage no gaps · no wind channels {/* Square */} Square {/* Wind channel highlight along aligned seams */} ~90% effective coverage aligned seams channel wind {/* Round */} Round floats 85–90% effective coverage 9–10% gaps between floats
### Central-dome profile Each tile carries a raised central dome — the visible curve on the upper face of the AWTT element. The dome does three jobs simultaneously:
{/* Water beneath */} water surface {/* Tile cross-section centered */} {/* Outer shell with dome profile */} {/* Sealed ballast water (interior) */} {/* Submerged portion shade */} {/* Rainfall arrows shedding off dome */} {/* Wind energy across dome */} wind dissipated rainfall sheds {/* Callout: central dome */} central dome {/* Callout: ballast chamber */} sealed ballast chamber {/* Callout: side wall */} raised side wall
- **Rainfall shed.** Rainwater rolls off the dome toward the seams between adjacent tiles and returns to the water body. No pooling on top of the cover. No accumulated load that would flatten the buoyancy. - **Wind dissipation.** The curved profile dissipates wind energy across the surface of the tile rather than concentrating it at a flat edge. Hexprotect® AQUA's 260%+ self-loading factor under wind (AWTT-published) is the engineered consequence. - **Tessellation tolerance.** Small height variations between adjacent tiles (caused by partial ballast variation, fouling, or tile age) are absorbed by the dome's overlap geometry — the seal does not fail at the seam. ### Self-ballasting or pre-ballasted retention The tile holds its position on the water surface by ballast — water carried inside the tile or sealed in the moulded shell — rather than by external anchors. Two patented engineering routes exist:
{/* Self-ballasting (left) */} Self-ballasting Original Hexprotect® · AWTT 2010 patent {/* Water beneath */} {/* Tile shell with open side port */} {/* Open side port — notch cut into side wall */} {/* Interior ballast — partially filled from the port */} {/* Water inflow arrow into side port */} water enters on install {/* Failure-mode callout */} open chamber · biological ingress · ballast loss on tip {/* Pre-ballasted (right) */} Pre-ballasted Hexprotect® AQUA · 2009 release {/* Water beneath */} {/* Tile shell — fully sealed */} {/* No side port — solid wall */} {/* Interior ballast — fully filled */} {/* Seal/lock badge */} sealed at factory {/* Benefit callout */} sealed chamber · no ingress · ballast retained on tip
- **Self-ballasting (original Hexprotect®, 2010 patent).** Water enters the tile through engineered side ports on install. The geometry prevents light entering the chamber and lets water drain back out cleanly on retrieval. Read the [original Hexprotect®](/heritage/original-hexprotect) story. - **Pre-ballasted (Hexprotect® AQUA, 2009 release).** Ballast water is sealed inside the one-piece moulded shell at the factory. No internal harbour for algae or bacteria, no ballast loss when a tile tips, smooth outer surface that sheds debris. Read the [Hexprotect® AQUA refinement](/heritage/hexprotect-aqua-refinement) story. For the engineering rationale of why pre-ballasted replaced self-ballasting as the workhorse, see [/self-ballasting-cover](/self-ballasting-cover). ## Benefits of the hexagonal geometry | Benefit | Value | Source | |---|---|---| | Effective surface coverage | 99% | AWTT | | Evaporation reduction | up to 95% | AWTT | | Sunlight blocking (algae) | 99% | AWTT | | Wind certification (Hexprotect® AQUA) | 130+ MPH (209+ km/h) | AWTT | | Self-loading under wind (Hexprotect® AQUA) | 260%+ | AWTT | | Anchorless install | yes | AWTT | | Tolerant of irregular shorelines | yes | AWTT | | Tolerant of fluctuating water levels | yes | AWTT | | Patent origin | AWTT 2010 (self-ballasting) | AWTT | ## When to specify a hexagonal floating cover - Surface area exceeds ~1,000 m² (the tessellation packing density and the anchorless install dominate at scale). - Surface-management goals are evaporation, algae, odour, or heat — not biogas capture. - 25-year operating horizon (Hexprotect® AQUA, AWTT-published) is the procurement basis, or 15-year (Hexofloat®, EuroCover-published) is acceptable with EU origin / shorter lead time as the trade-off. - Wind exposure is bounded — 130+ MPH for AQUA, 75 MPH for Hexofloat®. - Site cannot be drained (operating reservoir, active tailings pond, live digester adjacent). ## Hexagonal vs other floating-cover geometries | Geometry | Coverage | Mechanism | Best for | |---|---|---|---| | Hexagonal modular | 99% | Tessellating tiles, anchorless | Reservoirs > 1,000 m², 25-year horizon | | Spherical (Armor Ball AQUA) | ~91% (close pack) | Floating balls, anchorless | Small / irregular bodies < 500 m² | | Continuous geomembrane | 100% | Single sheet, anchored | Biogas capture, full containment | | Square modular | under 90% effective | Aligned grid, channels wind | Rarely competitive | | Round floats | 85–90% | Loose pack, leaves gaps | Light shading only | ## What copies typically get wrong The hexagonal shape is visible and easy to imitate. The patented engineering — and the AWTT refinements that make the hexagonal cover survive 25 years of industrial service — is not. See [/why-copies-fail](/why-copies-fail) for the catalog of failure modes that copies typically reintroduce. ## Sources - AWTT — [Hexprotect® AQUA hexagonal cover](https://www.awtti.com/products/hexprotect-aqua/) — manufacturer's canonical product reference; source of the 99% effective coverage, 130+ MPH wind, 260%+ self-loading, and patent-history values cited above. - US Department of Energy — recognition of AWTT cover heat-retention contribution. - USDA Bureau of Reclamation — evaporation suppression research (independent field measurements). ## Frequently asked questions ### Why hexagons and not squares or circles? Hexagons are the only regular polygon that tessellates without gaps and packs at the highest two-dimensional density (~91% area-fill geometrically; 99% effective coverage with the engineered AWTT geometry). Squares pack with seam-aligned grids that channel wind. Circles leave 9–10% of the surface uncovered between tiles. ### What is the central dome for? Three jobs at once: it sheds rainfall toward the seams between adjacent tiles (back into the water body, not pooling on top of the cover); it dissipates wind energy through the curved surface; and it raises the tile's tessellation tolerance — small differential heights between adjacent tiles still seal because the dome geometry overlaps consistently. ### Self-ballasting vs pre-ballasted — which is right? Both are AWTT-patented. The original Hexprotect® (2010 patent) is self-ballasting — water enters the tile through side ports on install and acts as ballast. Hexprotect® AQUA (2009 release) is pre-ballasted — the ballast is sealed inside the moulded shell at the factory. AQUA replaced the original as the workhorse because the pre-filled chamber resolved three failure modes of the original design. See [/self-ballasting-cover](/self-ballasting-cover) for the engineering detail and [/heritage/hexprotect-aqua-refinement](/heritage/hexprotect-aqua-refinement) for the timeline. ### What wind speed can a hexagonal cover handle? Hexprotect® AQUA is hurricane-rated to 130+ MPH (209+ km/h) — AWTT-published. The 260%+ self-loading factor under wind comes from the pre-ballasted mass and the central-dome geometry. Hexofloat® carries a 75 MPH envelope (EuroCover-published) at a lighter tile and shorter EU lead time. ### Does the cover need anchors? No. Anchorless installation is the defining feature of the AWTT hexagonal cover platform — each tile retains position by ballast (pre-filled inside the moulded shell on AQUA, ported on the original) and by the friction-and-overlap of the tessellation. No anchor system to install, maintain, or replace. ## Sources - Hexagonal tessellation achieves 99% effective surface coverage. — [AWTT — Hexprotect® AQUA hexagonal cover](https://www.awtti.com/products/hexprotect-aqua/) - Hexprotect® AQUA is hurricane-rated to 130+ MPH (209+ km/h) and self-loads at 260%+ under wind. — [AWTT — Hexprotect® AQUA hexagonal cover](https://www.awtti.com/products/hexprotect-aqua/) - AWTT 2010 patent — original self-ballasting hexagonal floating cover. — [AWTT — Hexprotect® AQUA hexagonal cover (provenance)](https://www.awtti.com/products/hexprotect-aqua/)