Fathomline is a free, browser-based on-bottom stability calculator for subsea pipelines. Enter your section, run the DNV-RP-F109 check, and read pass or fail in seconds — with a printable report you can drop into your deliverable pack.
An on-bottom stability check, without the spreadsheet wrangling or a heavyweight desktop licence.
Pipe build-up (steel, coatings, concrete, marine growth), the seabed soil, and the environmental sea states — with inline guidance on every field and a live total-OD readout.
One click computes both the installation and operational conditions using your chosen DNV-RP-F109 criterion — Absolute or Generalised (0.5 D / 10 D / intermediate).
See stable / unstable, the utilisation, and a full intermediate breakdown — then print or save a clean DNV-RP-F109 report as a PDF.
Built for pipeline engineers who need a defensible answer fast.
A faithful implementation of the DNV-RP-F109 method, checked case-for-case against established commercial software — so your results hold up in review.
Run the Absolute (no-movement) criterion or the Generalised displacement criteria (0.5 D, 10 D, or an intermediate y/D) — whichever your design basis calls for.
Every heading carries its own Hs, Tp and current per return period; the tool evaluates them all and reports the governing (heaviest) condition automatically.
Press Run and read pass/fail with the full intermediate breakdown, then export a tidy DNV-RP-F109 report to PDF for your documentation.
It runs in any modern browser on any machine — no licence dongle, no IT ticket, no version drift. Just open the link and start.
No sign-up, no account, no paywall to see if it fits your workflow — open the calculator and check a real section right now.
Open the on-bottom stability calculator, enter a case, and press Run. No sign-up needed.