Design Principles

1. Prioritize Natural, Soft, Living Materials

+

Manufactured materials degrade and weaken over time, whereas living organisms strengthen over time and self-renew. Hard materials reflect incoming energy, which may cause damage elsewhere, and they may break under extreme force—by contrast, soft materials are flexible and absorb energy. When a design requires a certain material property, we investigate where it occurs in nature and under what conditions, and attempt to incorporate the natural option whenever possible. This approach has led us to create a resilient hybrid ecosystem for our structures that is not a replica of any one natural living ecosystem.

2. Elemental Engineering

+

Our rigorous design method prioritizes elemental simplicity. We shy away from moving parts, embedded sensors, or “add on” solutions to design problems, instead focusing on the fundamental relationships between materials, organisms, and energy at a systems scale.

3. Modularity, Scalability, Replaceability

+

We design with regularity and redundancy. This gives us the ability to expand over time as budgets allow, and to know that failure modes are not catastrophic. Our system can be spot fixed or have components swapped out easily. There will always be situations more extreme than our design can handle, so we design with maintenance in mind rather than presuming to design for permanence.

4. Ecosystems First

+

We begin our design with intended beneficial effects on the local ecosystem, rather than solving an engineering problem and assessing its side-effects after the fact. Our approach prioritizes the creation of new habitats and the improvement of existing habitats, using ecosystems as a design guide every step of the way as we address the urban design challenges.

Individual Module

1

Salt marsh vegetation creates a dense tangled root network that binds substrate material together and provides a surface for microorganism growth as well as habitat for larger organisms. Root mass microorganisms enhance water quality and provide additional buoyancy through their biological processes

2

The outer net pouch holds the module together and encapsulates the inner substrate material.

3

The link points connect one module to the next. Each module’s link points are connected via loops and splices to avoid vulnerable connection hardware.

4

Inside the unit, the triangular tension yoke transfers the connection forces throughout the module. Friction fragments are lodged laterally in the rope loop to lock it in and help distribute external pull forces throughout the unit’s internal mass.

5

Submerged vegetation colonizes the bottom surface of the unit, providing extra friction and habitat for aquatic organisms.

Components

Encasement: Outer Net Pouch

Encasement: Outer Net Pouch

The net holds the unit together and ensures the inner components stay tightly packed inside. Additionally, it provides a strong surface for the growth of seaweeds, macroalgae, and other larger aquatic organisms.
Salt Marsh Vegetation

Salt Marsh Vegetation

Spartina alterniflora (smooth cordgrass, or marsh grass) is the main emergent (above-water) growing species. Dense root mass extends down into the substrate, further binding the substrate materials together over time.
Frictional Tension Yoke

Frictional Tension Yoke

The continuous triangular cross-connective loop extends through the volume of the unit. This element transfers network pull forces to the bulk of the unit rather than stressing the outer net or a singular edge point.
Growing Substrate

Growing Substrate

A mix of biomass byproducts provides the bulk of the unit. This mix buffers wave action, creates a substrate for rhizomatic growth, and encourages biofilm development by increasing available surface area.
Floatation Elements

Floatation Elements

Marine foam provides sufficient buoyancy to maintain floatation for the individual units. Natural materials that are buoyant unfortunately degrade rapidly.

Prototypes

The individual module contains all the determining features that contribute—at a larger scale—to the overall performance of the Emerald Tutu.

Our most recent generation of “sister” prototype launched in May 2022

Our first fully-functional prototype, launched in East Boston in May 202

Our first test launch in Cotuit Bay in February 2021

Network and Connections

1

Unit spacing and mooring design focus on avoiding detrimental impacts to the existing ecosystem, including seafloor scouring and overshading.

2

Unit-to-unit connections create a dynamic force-transfer network, dispersing energy throughout.

3

The network is anchored to the sea floor with branching mooring lines to ensure fastening redundancy. Mooring points attach to three branching upper lines, each of which in turn connect to six units of a hex ring.

4

The network is flexible and the units are soft. These properties minimize impact damage and maintain recreational and commercial uses.

Networks and connections are the systems that synthesize natural processes and human-made materials. This section highlights the critical balance of function, efficiency, and stability at multiple scales that make this design a viable nature-based solution to coastal flood protection.

MATERIAL INTERFACES, INSIDE THE UNIT

Internal material interfaces ensure stability and solidity of the individual unit, binding together the growing substrate, the floatation elements, the planted vegetation, and the tension yoke. This engagement is crucial to ensure the soft unit maintains its form despite continual wind and wave action. The perpendicular frictional elements of the triangular tension yoke loop distribute the pull forces from neighboring units to the bulk of the unit biomass. These wood fragments are lodged into the substrate mix, preventing the loop from slipping through it.

unit xray

UNIT-TO-UNIT, NETWORK CONNECTIONS

Individual units are connected to each other in a hexagonal network formation. In a dynamic offshore location, units are continually exerting pull forces on their neighbors. Thanks to the three-line unit interconnection geometry, each unit splits incoming pull forces into two component ±120-degree pull forces, diminishing point forces by spreading the energy out through the network.

NETWORk

BRANCHING ANCHOR LINES

The anchoring scheme uses branching vertical lines for structural redundancy while limiting the number of required seafloor mooring points. The unit-to-unit connection lines are intercepted by vertical branching lines, which in turn connect at hex centers to a mooring point. Elastic “conservation moorings” and helix-style attachments limit seafloor scouring and disturbance.

quiver