Stability & Hydrostatics
Stability Booklet Services
Navtech prepares, updates and gets approval for trim and stability booklets — for new vessels, after conversions and equipment installation, and for older ships whose original documentation is missing, outdated or no longer matches the vessel.
When a stability booklet needs updating
A stability booklet describes a specific vessel in a specific condition. Once that condition changes, the booklet stops being valid — and class or port state control will eventually notice. The common triggers are more frequent than owners expect.
- Equipment installation — BWTS, scrubbers, cranes, boilers or generators
- Structural modification, deck strengthening or superstructure changes
- Change of service, cargo type or trading area
- Lightweight change confirmed by a new inclining experiment
- Booklet lost, never approved, or approved to superseded criteria
- Class or flag comment requiring damage stability to current rules
Intact and damage stability analysis
We build or rebuild the hull and compartment model, then run the full criteria set applicable to the vessel type and flag. Loading conditions are developed around how the vessel is actually operated, not just the minimum set needed to pass, so the booklet remains a usable tool for the master rather than a document that lives in a drawer.
- Intact stability to the IMO Intact Stability Code and flag requirements
- Damage stability — deterministic and probabilistic methods as applicable
- Progressive flooding and cross-flooding assessment
- Grain, timber, offshore supply and special-service criteria where relevant
- Realistic operational loading conditions with departure and arrival cases
Inclining experiments and lightweight surveys
A booklet is only as reliable as the lightweight data behind it. Where the recorded lightweight is doubtful — after a long service life, major repairs or an undocumented conversion — an inclining experiment re-establishes the baseline. We prepare the procedure for class approval, attend on board to supervise the experiment, and issue the report.
- Inclining experiment procedure preparation and class approval
- On-board attendance and supervision of the experiment
- Lightweight survey and deadweight verification
- Inclining report and revised lightweight particulars
Hydrostatic data and loadicator support
Alongside the booklet we produce the underlying hydrostatic dataset, and where owners want an operational tool we build and support custom loadicator software tied to the approved data — so what the crew calculates on board matches what class approved on paper.
- Hydrostatic tables, KN cross curves and Bonjean data
- Capacity, sounding and ullage tables
- Still water shear force and bending moment envelopes
- Loadicator data files, verification and class approval support
Frequently asked questions
How long does a stability booklet take to prepare and approve?
For an equipment installation on a vessel with reliable existing data, typically two to four weeks including class submission. A full rebuild involving 3D scanning, model reconstruction and an inclining experiment usually runs six to twelve weeks, largely governed by vessel availability rather than calculation time.
Can you produce a booklet if the original drawings no longer exist?
Yes, and it is a routine situation on older and second-hand tonnage. We reconstruct the hull and compartment geometry from a 3D laser scan or measured offsets, then validate the model against an inclining experiment so the result is defensible to class rather than an estimate.
Do we need a new inclining experiment after a conversion?
Usually yes if the lightweight or centre of gravity has changed materially. Class rules set thresholds, and significant conversions almost always exceed them. In some cases a detailed weight calculation is accepted instead — we will confirm with your society before you commit to dock time.
Which class societies do you submit stability documentation to?
BV, DNV, RINA, ABS, Indian Register of Shipping and Tasneef most frequently, and we prepare to flag state requirements alongside class. We manage the comment cycle through to stamped approval rather than handing over calculations and stopping.
What do you need to quote a stability booklet?
Vessel particulars and class society, the existing stability booklet and general arrangement if you hold them, details of any modification, the date of the last inclining experiment, and your target approval date.
Related engineering services
Have a vessel and a scope in mind?
Share your drawings, class society and target dates — we respond within 24–48 hours.