Beam Reactions, Propeller Overhang, Jack-Up Load, Bearing Pressure, Relative Slope, Running Load Shift & Hydrodynamic Oil-Film Screening

Propulsion Shaft Alignment, Jacking Load, Bearing Load & Stern-Tube Oil-Film Risk Tool

Screen the shaftline beyond static bearing load alone. Estimate aft and forward bearing reactions, propeller overhang moment, shaft self-weight, bearing projected pressure, measured jack-load correlation, relative shaft-to-bearing slope, running-condition propeller load shift, critical hydrodynamic lubrication speed, EAL / viscosity sensitivity and the cost exposure behind an alignment correction or stern-tube bearing intervention. Advanced mode solves an Euler-Bernoulli beam model from shaft segments, bearing positions and vertical offsets.

Currency
Currency selector changes display only. No exchange-rate conversion is performed.

Propeller, Shaft Speed & Running Load

tonnes.
m.
kW.
rpm.
rpm for oil-film screen.
kN downward positive. Use signed value from analysis if known.
% of MCR torque. Positive / negative direction depends on the entered case.
±% of MCR torque for owner sensitivity, not a universal class limit.

Simple Two-Bearing Overhang Model

A fast static screen for the aft and forward stern-tube bearings. It intentionally does not model the full engine / intermediate-bearing shaftline.

m center-to-center.
tonnes, treated as uniform load.
kN representing the forward shaftline contribution omitted by this local two-bearing model.
mm.
mm.
mm.
mm.
kN at lift-off / interpreted test point.
Model / maker correction from measured jack load to inferred bearing reaction.
mrad.

Advanced Shaft Segments

Segments start at the propeller center (x = 0) and run forward sequentially. Shaft self-weight is calculated from diameter, bore and material density.

SegmentLength mOD mmBore mmE GPaDensity kg/m³

Advanced Bearing Register

Vertical offset is the prescribed bearing-center elevation relative to the model datum. Jack correction should come from the approved alignment / influence-coefficient model where available.

Bearingx from prop mOffset mmLength mmJournal mmBearing slope mradMeasured jack kNJack factor

Bearing Acceptance Criteria

kN owner / class / maker screen against unloading.
MPa project criterion. Enter the approved value.
mrad project criterion.
±% measured-inferred versus calculated static reaction.

Aft Stern-Tube Lubrication Screen

This uses a transparent Sommerfeld-type oil-film formation index. It is not the proprietary DNV oil lubrication criterion and does not calculate local contact pressure or minimum film thickness.

mPa·s at the actual operating oil temperature.
mm total diametral clearance.
Editable owner screening threshold, not a class criterion.
%. Keep 100 unless supported by lubricant / analysis data.
% operating rpm above calculated screening critical rpm.

Alignment / Bearing Intervention Cost Context

Selected currency/day.

Alignment Verification Readiness

Engineering screening only: This tool is not a class-approved shaft alignment calculation, bearing contact analysis, Reynolds-equation lubrication model, finite-element hull deflection analysis, strain-gauge alignment, jack-up test procedure, whirling / torsional analysis, propeller hydrodynamic analysis, bearing clearance acceptance or repair authorization. Jack influence factors, bearing pressure limits, relative-slope limits and oil-film thresholds must come from the approved class / maker / designer basis for the vessel.
Engineering basis: Modern propulsion-shaft alignment practice evaluates more than static projected bearing pressure. Bearing jacking is used to verify static vertical load, while detailed alignment analysis can also consider bearing reactions, shaft deflection and bending moments, relative shaft-to-bearing slope, propeller-induced running loads and aft stern-tube hydrodynamic lubrication. Lubricant viscosity and lubricant type can materially affect aft-bearing oil-film margin, especially in low-speed or high-load transient conditions. The simplified oil-film index in this tool is intentionally transparent and editable and is not a substitute for class software or approved bearing lubrication calculations.
Generated by ShipUniverse.com
By the ShipUniverse Editorial Team — About Us | Contact