Input data checked
It can organize scantling, material and loading condition tables in the format each tool accepts, checking units, empty fields and unmatched items before running.
Deliverable: input spreadsheet + list of open issuesOcto for hull structure and classification
The calculation belongs to the tool. The approval, to the classification society.
Each classification society distributes its own software to check hull structure against its rules and the Common Structural Rules (CSR) of IACS, the international association of classification societies. Around these tools, Octo can prepare input data, run what accepts scripts, read finite element results and draft reports, all for human review. The one who signs is the engineer in charge; the one who approves is the classification society.
Classification societies surveyed6DNV, ABS, LR, BV, RINA, ClassNK, each with its own software
New CSRJul 1, 2029expected entry into force, according to IACS
BV MARS 20002.9rfree of charge, according to BV (Sep 15, 2025)
Sources18listed at the end of the page
01
What Octo does around the structure.
Six possible deliverables, drawn from the research. All of them use the tools the client already has installed and licensed; none replaces the check in the classification society's tool, and all of them go to review by the engineer in charge.
Batch runs
It can launch the checks that the tool allows by script: Sesam Core, Sestra and Wasim through the Python package dnv-sesam-commands; GeniE through JavaScript; Femap through its API. Each run is logged.
Stresses by region
It can read Nastran files (.bdf and .op2) with the open-source pyNastran and list the maximum stress by property or region, against a limit the engineer provides from the rule.
Revision against revision
It can compare two runs (thickness, material, result) and show what changed, for whoever will answer the classification society's comments.
Deliverable: differences reportDraft report
Proposes the draft of the calculation report or of the reply to comments, with every number linked to its source file, for the engineer to review and sign.
Deliverable: traceable draftThickness measurement
It can cross the measurement company's spreadsheet with the design thickness and the allowable wastage provided by the engineer, separating what is within limits, in attention or beyond, for the surveyor and the shipowner to decide.
Deliverable: status point by point
02
Eight arms, one hull.
The same Octo cycle, applied to structure and classification. Each arm has a narrow role; the one who signs is the engineer in charge and the one who approves is the classification society.
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Discovery
Identifies tool and rule
Which classification society, which software and version, which rule edition applies to the ship. The tool version has to match the contracted edition.
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Data
Pins down units and names
Model units, names of properties, materials and load cases. Without this agreement, two runs cannot be compared.
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Security
Sorts out confidentiality first
Client designs are confidential; a naval vessel may involve controlled data. Nothing leaves the client's machine without approval from the responsible team.
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Architecture
Chooses the path
Python in Sesam, JavaScript in GeniE, the Femap API, pyNastran to read results, PyMAPDL for studies. The rule check always stays in the classification society's tool.
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Development
Writes the script
Prepares the batch or reading script with the limit and the rule provided by the engineer, never taken from memory.
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Review
Checks against a known case
Compares the script output with what the tool itself shows for the same element and the same load case. It checks by the number, not by the absence of errors.
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Release
Runs in the authorized environment
Only with your OK, it runs on the machine where the tool is licensed and leaves the spreadsheet or the draft right there for review.
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Documentation
Records what applies to your project
Tool, version, rule edition and what was checked. The script for one ship is not taken as ready for another.
Octo does not approve designs or assign class. Approval, class and certificates belong to the classification society and the maritime authority; the design has a qualified engineer in charge. Sending controlled data (ITAR/EAR, U.S. export control regulations) to any external service, including AI, must first be assessed by the client's compliance team.
03
Every task, its own path.
The criteria Octo uses to choose. The rule check stays in the classification society's tool.
| Task | Path | Notes |
|---|---|---|
| Run Sesam checks in batch | dnv-sesam-commands (SesamCoreCommand, execute_command) | Sesam installed and licensed |
| Repetitive geometry or loads in GeniE | GeniE JavaScript script | Commands in the GeniE documentation, behind a login |
| Read stresses from a Nastran model (VeriSTAR Hull, Femap) | pyNastran (read_bdf, read_op2) | CSV for the engineer to check |
| Parametric study of a detail | PyMAPDL (Mechanical APDL) | A study, not a rule check |
| Take the model from CAD to the classification society's tool | NAPA Steel ↔ ABS UDM Utility; NAPA Designer → PrimeShip-HULL; NAPA and Tribon → RulesCalc | Each path comes from the tool vendor |
| Check thickness measurement | Measurement spreadsheet + comparison script | Allowable wastage provided by the engineer |
04
From a one-off script to a design routine.
Three steps. Each one only makes sense after the previous one has shown results on your project and passed review by the engineer in charge.
A proposal, not a promise
Reading and checking on demand
On the machine where the tool is licensed, you ask in engineering language and Octo proposes the script and the spreadsheet.
- “Highest stress per double bottom plate” becomes a script + CSV
- A check on a known element before trusting it
- Limit and rule edition noted in each file
Routine runs and comparisons
Batch runs and the comparison between revisions can start running with each new model version, in the client's environment.
- Sesam batch per load case, with a log
- Differences between revisions to answer comments
- Thickness measurement cross-checked at each survey
Drafts and rule changes
The calculation report can come out as a traceable draft, and each new rule edition can become an impact list for the engineer to assess.
- Report draft with the source of each number
- List of what changes with the new CSR, based on the published text
- Log of tool, version and rule per project
05
Confirmed by a source.
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.
- ConfirmedSesam runs from Python
- The
dnv-sesam-commandspackage (5.23.1.0, MIT license) runs Sesam Core, Wasim and Sestra commands as from the command line, withSesamCoreCommandandexecute_command.Source: package page on PyPI, May 2, 2025 - ConfirmedCurrent DNV and BV versions
- Sesam GeniE 9.3-00 (Oct 1, 2026), Sesam Core 5.4-00 (Oct 21, 2026), Nauticus Hull ver 21.3 (Sep/2026); BV MARS 2000 2.9r (Sep 15, 2025) and VeriSTAR Hull 5.30 (Dec 5, 2025).Source: DNV release notes; product pages on the BV site
- ConfirmedThe CSR will change
- According to IACS (Council meeting C90), the new CSR are expected to be adopted on Jul 1, 2027 and to enter into force on Jul 1, 2029. The edition in use is Jan/2024, with the Jan/2025 corrigenda in the text published by BV (NR606).Source: IACS news; NR606 page on the BV site
- ConfirmedWho uses it, with a source
- According to BV, VeriSTAR Hull uses Femap with Simcenter Nastran and MSC Nastran; according to ClassNK, PrimeShip-HULL direct analysis uses Simcenter; according to ABS, Eagle Express runs inside Femap.Source: product pages at BV, ClassNK and ABS
06
What Octo does, and what stays with you.
Octo prepares everything, but it does not sign. The document of record stays with whoever is accountable for it.
Octo prepares
Surveys, calculates, organizes and produces the documents: spreadsheets, reports, lists and drafts.
Deliverable: material ready to checkYour team checks
The 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 signsWho signs
Octo 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 society
07
Sources.
Documentation and pages from the classification societies themselves, IACS and the vendors, used in the research.
- Sesam: release notesDNV, GeniE 9.3-00 (Oct 1, 2026)
- Nauticus Hull: what's newDNV, ver 21.3 (Sep/2026)
- Nauticus Hull and Sesam in cargo hold analysisDNV
- dnv-sesam-commandsPyPI, 5.23.1.0 (May 2, 2025)
- ABS: engineering softwareEagle family
- LR: RulesCalcScantling check
- LR: ShipRightStructural and fatigue assessment
- BV: MARS 20002.9r (Sep 15, 2025)
- BV: VeriSTAR Hull5.30 (Dec 5, 2025)
- BV: NR606 (CSR BC & OT)Jan/2024 with Jan/2025 corrigenda
- RINA: Leonardo HullFEM and RINA rules
- ClassNK: PrimeShip-HULLPart C and Part CSR-B&T
- IACS: Common Structural RulesCSR BC & OT
- IACS: Council meeting C90New CSR in 2027 and 2029
- Simcenter: latest versionSiemens, Femap 2606
- Synopsys completes the Ansys acquisitionSynopsys press release, Jul 17, 2025
- PyMAPDL: launching MAPDLPyAnsys documentation, 0.74.1
- pyNastran: reading OP2Project documentation
Your calculation, ready for review.
The assessment starts with the tools you already have and the rule contracted for the ship, without changing anything. You get a proposal of what can be prepared, run and checked around them, and you decide with that in hand.