Lorica

Fouling risk and intervention selector. Decide, surface by surface, whether growth is a defect to suppress or an asset to recruit, then rank the interventions on efficacy, cost, biocide load, and how good the evidence actually is.
v0.1 · design

Site forcing

Sets settlement rate and the length of the recruitment window. The strongest single driver.
The first-order filter on which assemblage is possible at all. Below ~18 PSU the hard-fouling barnacle and mussel load drops sharply.
Proxy for larval supply. Long residence retains propagules in the basin, which is why inner harbours foul harder than open coast at the same temperature.
Sets euphotic depth, which gates the algal (soft) fraction and also sets the depth limit for a soft accumulator.
Site fouling pressure --
Photic limit for a soft accumulator: --

The reframe

A harbour has two kinds of wetted surface and treating them the same is the error that makes fouling management expensive and ecologically negative at the same time.

Surfaces where growth costs function (intake screens, heat exchangers, moving parts, inspection windows, load-critical members) need suppression, and the only question is which suppression.

Surfaces where growth costs nothing (quay walls below the tide line, pile jackets, riprap, fender faces) are free hard substrate in a system that has usually lost most of its natural hard substrate. Suppressing those pays money to destroy habitat and adds copper to the sediment for no operational return.

Lorica forces that allocation to be explicit per surface. The nature-based half of the product is not only the bio-derived coating: it is the decision to stop coating the surfaces that never needed it, which is usually the larger effect and is free.

Asset surfaces · edit inline, the verdict recomputes

SurfaceArea m²Depth band FlowFouling costs whatAccess PressureConseq.RiskVerdict
Verdict rule. Consequence, not pressure, decides suppress versus recruit. A surface can foul hard and still be a recruit surface if the fouling costs nothing, and that is the whole point. Pressure decides how hard the chosen intervention has to work, which is what tab 2 ranks.

Choose a surface

What are you optimising for

Evidence is a first-class axis, not a footnote. Set it to zero and the bio-based options rise; set it high and the incumbent wins, because copper antifouling has decades of field data and a chitosan coating has 30-day panel results. Both of those are true statements and the tool should not hide either.

Ranked options

Wetted area allocation

Suppress Groom Recruit
--
kg Cu / yr, coat-everything baseline
Every wetted surface carried on the incumbent copper antifouling, which is the default many harbours are actually running.
--
kg Cu / yr, best-ranked plan
Each surface on whichever option currently ranks first under your weights.
--
kg Cu / yr avoided
The number a regulator and a port sustainability report both want, and the one the accumulator array in DESIGN.md section 8 would independently verify.
--
m² released to recruit
Hard substrate deliberately left to colonise. The cheapest nature-based intervention available, because it consists of not spending money.
--
€ / yr, annualised plan cost
Capex amortised over stated durability, plus opex. Placeholder coefficients.
--
evidence score of the plan, 0 to 3
Area-weighted. A plan that scores below 1.5 is a research programme wearing a procurement decision's clothes, and should be labelled as one.

Plan by surface

SurfaceVerdictSelected optionArea m²kg Cu/yr€/yrEvidence

Intervention coefficients · all editable, all assumptions

OptionClassEfficacy Durability yrkg Cu/m²/yr€/m² capex €/m²/yr opexEvidence
Efficacy is the fraction of fouling accumulation prevented on a static surface at moderate pressure, before the flow and pressure modifiers on tab 2 are applied. Evidence is 0 (mechanism only), 1 (short-duration panel data), 2 (multi-season field data), 3 (decades of operational record).

Where the numbers come from