Fathomline · On-Bottom Stability Calculator (DNV-RP-F109)

Report information

Client

Project

Case

Calculations by

Verified by

Date

Configuration

Stability criterion

Allowable displacementy/D

Design condition — installation (RPV)

Design condition — operational (RPV)

Pipe properties

Total OD — m

Steel outer dia m

Wall thickness m

Steel density kg/m³

Concrete coating m

Concrete density kg/m³

Marine growth m

Marine growth density kg/m³

Field-joint cut-back m

Field-joint density kg/m³

Pipe heading deg

Content density kg/m³

Seawater density kg/m³

Coating layers

Number of coating layers

Soil & resistance

Seabed soil

Lateral friction μ

Safety class factor — empty γ_SC

Safety class factor — oper γ_SC

Submerged unit wt (sand) N/m³

Dry unit wt (clay) N/m³

Undrained shear (clay) N/m²

Seabed roughness z₀ m

Trench depth z_t m

Trench wall angle θ_t deg

Extra penetration z_pu m

Permeable-seabed r_perm,z 0–1

Total load reduction, horizontal r_tot,y · calc

Total load reduction, vertical r_tot,z · calc

Water-filled penetration — installation (ABS)

Water-filled penetration — operational (ABS)

Environment & sea states

Water depth m

Storm duration hr

Reference height z_r m

Spreading exponent s

Boundary layer correction for current

Directionality

Number of directional combinations

JONSWAP peak enhancement γ

Calculate peak enhancement, γ

Calculate added concrete / steel thickness to pass

Result

Enter the inputs, then press Run to calculate the results.

Cross-section & force balance

SteelConcrete (CWC)Marine GrowthSubmerged wt

Installation (empty)—

—

Operational—

—

Full breakdown — governing case per condition

Quantity	Installation	Operational

Parametric study

sweeps one variable

Vary a single input across a range and watch how the stability check responds. Every other input is taken from the Single run tab.

Variable to sweep

Minimum

Maximum

Steps

Chart

Marine growth applies to the operational curve only. To change the base case (materials, soil, sea states…), edit the Single run tab and switch back — the sweep re-runs automatically.

Utilization vs variable

Results table