Free Engineering Tool

J-Tube Cable Pull-In Force Calculator

Build your own J-tube profile — add as many straight or curved sections as your design needs, choose each bend's direction, and see a scale diagram alongside the calculated static pull-in tension.

Scale Diagram — Cable Path

Global Parameters

Cable weight in airkg/m

Cable weight in waterSubmerged unit weight, kg/m

Cable outside diametermm

J-tube inner diametermm

Cable bending stiffness (EI)kN·m²

Torsional stiffness (J)kN·m² per degree

Starting / lay tensiontonnes

Starting headingdegrees from horizontal

Plan-view twist angle (Φ)deg, hang-off to guide bearing

CPS engagement allowancetonnes, applied then released

Sea surface heightm above seabed, optional — for diagram

Sections

Add as many straight or curved sections as your J-tube needs, in order from the seabed touchdown to the hang-off. Sections are auto-named Section N – Type_n based on position and type count.

Result

— kN

— tonnes-force

Add sections to calculate

Winch Selection

Factor of Safety (FoS)

There is no single codified factor for sizing a pull-in winch against a calculated static tension (unlike lifting gear SWL/MBL ratios under DNV 2.7-1). 2.0× is a commonly used starting point for routine pull-ins with well-understood friction and geometry; move towards 2.5–3.0× where inputs are uncertain, dynamic/snagging effects aren't separately modelled, or conditions are more severe. Always confirm against your project's or contractor's engineering standard.

Recommended min. winch SWL — kN

— tonnes

Section Breakdown

Section	Tension	Cumulative
Build your section list to see the breakdown.

Methodology: straight sections use the pull force F = W·(μ·cosθ + sinθ); confined curved sections add bending moment (EI/r) amplified by Eytelwein capstan friction (e^{μφ}) on the running cumulative tension, plus suspended arc weight; unconfined (free) bends add only suspended arc weight. Torsion uses J·Φ divided by the torsionally-restrained cable length. This is an indicative estimate only — verify against a full site-specific calculation before specifying winch or installation equipment capacity.