Cargo Optimizer

Chemical tanker stowage planner for M/T X (IMO 9000001, IBC ship type 2, 12 cargo tanks). No installation and no internet needed: open index.html in a browser.

Offline chemical tanker stowage planner and cargo optimiser: IBC Code ship type and segregation checks, filling limits, list and deadweight, with a C++ (WebAssembly) search engine.

Optimisation goals (in order of priority)

1. Stow the maximum cargo (every tonne that doesn't fit is the heaviest penalty).
2. Use the fewest tanks, and leave the least empty volume in the tanks used (best fit).
3. No slack tanks: a tank filled below an adjustable threshold (default 65 %) is heavily penalised, so one tank at 70 % is chosen over two tanks at 35 %.
4. List: the part that can be corrected with empty ballast on the opposite side is penalised lightly, anything beyond that heavily; a ballast suggestion is given for the correction.
5. P/S pairs preferred, slop tanks as a last resort.

Hard constraints: one parcel per tank, a filling limit per parcel, no common bulkhead between incompatible parcels, locked tanks are never touched.

Algorithm: "minimal sufficient" tank subsets for each parcel (12 tanks → 4096 subsets, capacity DP) plus their P/S symmetric closures; the most constrained parcel goes first, branch & bound with a capacity lower bound. Typical run time 10–800 ms.

C++ engine (v2)

The stowage search and the scoring done at every step (P/S moment, list during loading/discharge, slack, empty volume) are written in C++ in engine/stowage.cpp. They are compiled to WebAssembly and embedded in js/engine-wasm.js, so the app still runs by opening index.html, without internet. The UI, physics (VCF, filling limit) and compatibility stay in JavaScript.

• Settings → Optimiser engine: C++ — deep search (default, twice as wide a search), C++ — standard search (exactly the same plan as JS, ~25–40× faster), JavaScript (the previous engine).
• If WebAssembly can't be loaded, the planner falls back to the JavaScript engine automatically and shows a warning.
• Consistency: the C++ engine follows the same order of operations as JS and is compiled with FMA off (-ffp-contract=off); in standard search, JS, WebAssembly and the native build give bit-for-bit the same plan and score (tests/engine-parity.js).
• Native build (ship's computer, command line): npm run build:engine -- --native → build/stowage (input/output format at the top of engine/stowage.cpp).
• After changing the engine: npm run build:engine (needs clang + lld: sudo apt install clang lld). js/optimizer.js and engine/stowage.cpp are the same algorithm; a change to one must be made to the other too.

Calculations

• Density/VCF: petroleum products ASTM Table 54B, lube oil / base oil ASTM Table 54D (15 °C), chemicals and vegetable oils the product's expansion coefficient β. The method can be changed by hand in the form.
• Filling limit = min(98 % × ρ(max temperature on passage) / ρ(loading temperature), 98 % × 1.54 / ρ).
• Weight: in vacuum or in air (WCF −0.0011).
• Compatibility: USCG 46 CFR 150 Figure 1 reactive group chart (exception pairs are shown as warnings), plus heat-sensitive products next to heated cargo (styrene, VAM, acrylonitrile…).
• DWT: T/S/W load line zone chosen by hand, optional draft-restricted DWT.

Manual editing

• Click a tank → type %, m³ or tonnes; slider; step (0.5–100, t/m³/%); "Fill to limit", "Match pair", "Even out", "Empty".
• With Keep parcel totals on, a change in one tank is carried over to the other tanks of the same parcel, so the parcel total stays the same.
• Every cell in the tank table is editable; the parcel is picked from a drop-down.
• Drag a parcel onto a tank; drag a tank onto another tank to move or swap.
• Tank lock: Optimise leaves locked tanks alone. Adding a new parcel doesn't disturb the current plan (it only goes into empty tanks).
• DWT: if the nominations exceed the deadweight, Optimise warns and asks before scaling all parcels down proportionally (Cancel → full nomination, with a DWT overrun warning). The optimiser also takes the P/S imbalance of the current ballast into account.
• Undo / redo (Ctrl+Z / Ctrl+Y), autosave, save/open JSON, CSV, A4 landscape print (with signature blocks).

Themes

Chart (paper, default) · Bridge (dark) · Night (red, night vision) · Auto.

Tests

npm test          # calculation / optimiser tests + C++/JS parity test (Node)
npm run test:ui   # browser smoke test (installed Chrome, or CHROMIUM_PATH=/path/to/chromium)

Desktop version (Tauri)

npm run tauri build — dist-web/ is regenerated from index.html, css/ and js/ on every build (npm run build:web); don't edit it by hand.

The regulatory data is a planning aid; the ship's Certificate of Fitness, the current IBC Code Ch.17/18, the USCG chart and the charterer's/shipper's instructions take precedence.