Octo for hydrostatics and stability
Hydrostatics and stability are calculated in mature tools, such as NAPA, MAXSURF Stability, GHS, AutoHydro and DELFTship, and, on board, in loading computers approved ship by ship. With the exports from these tools, Octo can redo the hydrostatics independently, check righting arm (GZ) curves against the general criteria of the International Code on Intact Stability (2008 IS Code) and review the stability booklet, all prepared for human review. Approval belongs to the engineer in charge, the classification society and the maritime authority.
Six possible deliverables, drawn from the research. All of them start from the exports of the client's tool; none replaces the approved tool, and all of them go to review by the engineer in charge.
It can recalculate displaced volume, displacement, longitudinal center of buoyancy (LCB), KB, BM and KM from the table of offsets, or on a mesh with Capytaine, and point out where the result departs from the approved tool.
Deliverable: side-by-side table with the differencesIt can read the exported righting arm curve and compute the areas up to 30° and 40°, GZ at 30° or more, the angle of maximum GZ and the initial GM, with the margin for each general criterion (part A, item 2.2).
Deliverable: list of criteria with margins, for decisionProposes command files or automation calls (COM in MAXSURF, command files in GHS, macros in NAPA) to run many conditions in the licensed tool, and consolidates the results in a spreadsheet.
Deliverable: prepared batch + consolidated spreadsheetIt can check whether every required condition appears, whether units and signs are consistent and whether the numbers in the text match the tables. Whatever does not fit becomes a question for the engineer.
Deliverable: list of review pointsWith the loading computer export, it can compare the actual condition with the booklet conditions and highlight what departed from plan. The export format is defined ship by ship.
Deliverable: comparison for the master and the officeIt can note which software version, which model and which criterion produced each number, so the calculation can be redone and audited later.
Deliverable: record of version, model and criterionThe same Octo cycle, applied to stability. Each arm has a narrow role; the ones who approve and sign are qualified people, the classification society and the authority.
Which program and which version (NAPA, MAXSURF, GHS, AutoHydro, DELFTship, Orca3D), which modules are licensed and which exports exist: tables, curves, text reports.
Axis origin, positive direction, water density, draft and trim of each condition, free surface correction. Without an explicit reference, two results cannot be compared.
The lines plan and the stability booklet are the client's property. For a naval vessel, sending controlled data (ITAR/EAR) to any external service, including AI, must first be assessed by the client's compliance team.
CSV export and a check script when reading is enough; the tool's own automation (COM, command files, macros) when many conditions must be run, always on the licensed machine.
Prepares Python scripts for hydrostatics from offsets, general GZ curve criteria and consolidation of results, with the source of each limit noted in the file itself.
Before use, it compares with a result already approved: a booklet condition, a signed hydrostatic curve. It checks by the number, not by the absence of errors.
Only with your OK, it runs in the environment the client cleared and leaves the spreadsheet or the list right there, for the engineer in charge to decide.
Tool version, model, criterion and conventions of each calculation. The next job starts from this record, and the script for one ship is not taken as ready for another.
Octo does not approve stability booklets, inclining tests or loading computers. That belongs to the engineer in charge, the classification society and the maritime authority (in Brazil, the Brazilian Navy).
The criteria Octo uses to choose. The approved tool remains the reference; the scripts serve to check and consolidate.
| Task | Path | Notes |
|---|---|---|
| Design hydrostatics (curves, tables) | NAPA, MAXSURF Stability, GHS, AutoHydro, DELFTship, Orca3D | The tool used in the client's approved process |
| Independent check of displacement, LCB, KB and BM | Own script on a table of offsets, or Capytaine on a mesh | A check only; it does not replace the approved tool's calculation |
| GZ curve against the general criteria of the 2008 IS Code (part A, 2.2) | Tool export to CSV + check script | The engineer in charge decides; amendments and special criteria handled separately |
| Compare the on-board condition with the booklet | Loading computer export + script | Export format defined ship by ship |
Three steps. Each one only makes sense after the previous one has shown results in your design office or your fleet.
A proposal, not a promise
With the tool's exports, you ask in engineering language and Octo proposes the script and the table.
A project's loading conditions can start running in batch in the licensed tool, with consolidated results.
Loading computer exports can be compared with each ship's booklet, for the technical office to follow.
Every point below has a source published by the vendor, by the project or by the responsible agency. The sources are in the next section.
4
points with a published source, each with its reference shown alongside.
Octo prepares everything, but it does not sign. The document of record stays with whoever is accountable for it.
Surveys, calculates, organizes and produces the documents: spreadsheets, reports, lists and drafts.
Deliverable: material ready to checkThe licensed professional checks what Octo delivered before signing. If something doesn't add up, it goes back to Octo with the correction.
Step: checked by the person who signsOcto does not sign. Designs, technical reports, ART/RRT, statements of account and any official document are still signed by the licensed professional at the company or agency: here, the naval engineer in charge and the classification society.
Signature: naval engineer and classification societyDocumentation from the vendors, IMO and the classification societies used in the research.
The assessment starts with a curve or a condition you have already approved, without touching your tool. You get a proposal of what can be checked and consolidated in your process, and you decide with that in hand.
