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.

v0.4 · design

Site forcing

Peak summer water temperature

Sets settlement rate and the length of the recruitment window. The strongest single driver.

Salinity

The first-order filter on which assemblage is possible at all. Below ~18 PSU the hard-fouling barnacle and mussel load drops sharply.

Flushing / residence time

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.

Turbidity (Kd490)

Sets euphotic depth, which gates the algal (soft) fraction and also sets the depth limit for a soft accumulator.

Propagule pressure (vessel traffic + connectivity)

Non-indigenous species arrival rate. Fouled surfaces are the primary NIS vector and ports are the introduction hotspots, so releasing surfaces to recruit is only unambiguously good where this is low. Above the threshold, recruit becomes recruit-and-watch.

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

Surface	Area m²	Depth band	Flow	Fouling costs what	Access	Pressure	Conseq.	Risk	Verdict

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.

Wetted area allocation

Suppress Groom Recruit + watch 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

Surface	Verdict	Selected option	Area m²	kg Cu/yr	€/yr	Evidence

Intervention coefficients · all editable, all assumptions

Option	Class	Efficacy	Durability yr	kg Cu/m²/yr	€/m² capex	€/m²/yr opex	Evidence

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