A fall pipe hangs off a dredger roughly ten miles off the Sussex coast, its lower end a few feet above the sand.
Through it goes block after block after block.
More than seventy five thousand of them, onto one patch of seabed at the foot of one turbine.
Nothing in the load is large. The biggest piece would fit in a kitchen sink.
The blocks are small on purpose.
That is where the acreage comes from.
Why the same concrete cut smaller buys more surface
Cut a solid block in half along all three axes. You now have eight blocks, the same material, twice the outside face.
Volume scales with the cube of a length, surface with the square. Every time the pieces get smaller, the ratio between the two moves the same way.
That is the trick behind a reef block. A ton of concrete poured as one lump offers almost nothing to colonize. The same ton in fist sized pieces offers a great deal.
Rock armour does the same by accident, because graded rock is also a heap of separate lumps with gaps between them.
Marine growth lives on that skin. Barnacles, tube worms, sponges and hydroids settle on hard faces, and the fish that feed on them follow.
Volume follows the cube. Surface follows the square.
What actually went onto that piece of seabed
Surveys at one Rampion turbine had found a scour pit six to ten feet deep around the foundation, the ordinary consequence of a steel tube standing in moving water over mobile sand.
What went down the pipe was 75,100 concrete cubes in two sizes. Six inch cubes that are solid through, and fourteen inch cubes cast with internal passageways and chambers.
Together they weigh about 1,900 short tons. The mix is 98 percent recycled concrete, plastic free, cast in Truro in Cornwall.
A trial load of around twenty tons went first. The full placement followed in October 2025, laid by a specialist dredging contractor.
The patch of seabed all of it covers is about 8,800 square feet, which is a fifth of an acre.
The pit was real. The footprint is small.
Where six acres comes from and whether the number holds
The figure quoted for habitat surface is about 269,000 square feet, a little over six acres.
Worth checking rather than repeating. A six inch cube carries one and a half square feet of outside face. A fourteen inch cube carries close to eight.
The total weight implies about one large cube for every two and a half small ones. On that split the outside faces alone come to almost six acres.
The passageways inside the larger cubes account for the rest. The number is sound. It is a genuine count of concrete surface.
What it is not is six acres of seabed. All of it sits on that fifth of an acre, stacked into a mound a few feet thick, most faces pressed against other faces.
Six acres of concrete. A fifth of an acre of ground.
The comparison that decides whether six acres means anything
Something was always going onto that scour pit. The default is rock armour, which is not a smooth sheet either.
The developer puts the cubes at 38 percent more surface area and over 100 percent more habitat volume than standard rock protection.
The manufacturer’s own project page puts the same comparison at around 25 percent more surface and up to fourteen times more internal habitat space.
Two partners on one project, two sets of numbers, worth knowing before either is quoted as settled.
Either figure leaves the rock that was not laid accounting for four to five of those six acres. The gain is one acre or two.
The pit that started all of this was covered here in an earlier piece.
A Scottish wind farm with no scour protection at all still counted about half again as many fish close to its 24 jackets.
Rock gives most of it. Cubes add the remainder.
What the surveys can settle and what they cannot
Ecological and geophysical surveys are scheduled for 2026, 2028 and 2030. Nothing has been published yet.
The question is not whether animals turn up. They turn up on rock. It is whether the extra internal space holds more of them, and bigger ones.
A confounder sits in plain view. Bottom trawling is already excluded between the turbines of a working wind farm, so anything rich found there arrives with a second explanation attached.
The engineering side is further along. Stability under simulated extreme storm conditions was tested independently before consent, and that part is closed.
The turbine, the cube counts and the survey timetable are set out by the developer.
The seabed footprint and the comparison against rock armour are given by the manufacturer.
The concrete cubes are down there doing their job, and the six acres they carry is a measurement rather than a place.
