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Alignment · Chocking · Vibration

Marine engine and generator alignment.

Shaft alignment, coupling alignment and generator alignment measured properly — afloat or in the dock — with mount and chocking work, vibration assessment and a signed measurement report.

Methods
Dial gauge · Laser · Feeler
Scope
Main engines and gensets
Includes
Mounts, chocks, couplings
Output
Signed measurement report
Why alignment matters

Misalignment is a slow, expensive failure

A shaft line that is out by a few hundredths of a millimetre feels like nothing at the helm and behaves like a hammer inside the gearbox. Misalignment shows up as stern tube and seal wear, hot or noisy bearings, coupling bolt fatigue, gearbox output-shaft damage, cracked engine mounts and vibration that crew simply learn to live with. It is one of the cheapest things to measure and one of the most expensive to ignore.

We align main engines to gearboxes and shaft lines, and generator sets to their alternators, on superyachts and commercial vessels. Every job ends with numbers on paper.

When to align

When an alignment check is due

  • After any engine, gearbox or shaft removal or re-installation — including after an overhaul.
  • After a grounding, a fouled propeller, a heavy line strike or a rope in the shaft.
  • When engine mounts are replaced, or when resilient mounts have aged and settled.
  • When new vibration, noise or heat appears in the shaft line or gearbox.
  • After launch, when the hull has settled — a hull aligned on the hard will move afloat.
  • At intervals recommended by the gearbox and coupling manufacturers, and as part of major surveys.
Method

How we measure and correct

StepDetail
Pre-checksVessel condition noted: afloat or ashore, fuel and water state, hull temperature, time since launch. Alignment is only meaningful with the conditions recorded.
Coupling measurementRadial and axial run-out, gap and sag measured with dial gauges, feeler gauges or laser equipment across four positions.
Bearing and mount surveyShaft bearing wear, stern tube and seal condition, mount height, compression and cracking, chock condition and bolt torque.
CorrectionMount height and lateral position adjusted, mounts renewed where required, resin or steel chocks fitted, bolts torqued to specification.
VerificationRe-measurement to manufacturer tolerance, then a running check for vibration and temperature under load.
ReportBefore and after figures, tolerances, parts fitted and observations — signed and dated for the vessel's file.
Alignment measured with the vessel just relaunched, or with tanks in a different state from normal operation, can read fine and still be wrong at sea. We record the conditions and, where accuracy matters, re-check after the hull has settled.
Generators

Generator and alternator alignment

Genset alignment gets forgotten because the set is bolted together at the factory. Rubber mounts age, frames flex, and coupling wear then shows up as bearing failures and cracked flexible elements. We align engine to alternator, check mounts and coupling elements, and confirm the result under electrical load — see generator service and repair.

Questions we get asked

Frequently asked questions

Can shaft alignment be done with the vessel in the water?

Yes, and for many vessels afloat is the more representative condition. What matters is that the hull has settled and the loading state is recorded, so results are comparable between checks.

What alignment tolerance should the coupling be within?

It depends on the coupling and gearbox specification — commonly in the range of a few hundredths of a millimetre per 100 mm of coupling diameter. We work to the figures published for your specific gearbox and coupling, not to a generic rule.

How long does an alignment job take?

A measurement and report on one shaft line is typically a single day. Correction work with mount renewal or chocking usually adds one to three days, plus resin cure time where resin chocks are used.

Do you supply a report we can give to class or the owner?

Yes — a signed before-and-after measurement report with tolerances, conditions and parts fitted.

Can you diagnose vibration that is not alignment?

Yes. Vibration can come from propeller damage or imbalance, a bent shaft, worn bearings, engine misfire or mount failure. We measure before concluding, so you are not paying to re-align a shaft when the real fault is a damaged blade.

Service enquiry

Tell us about the engine and the vessel.

Send the details below and you will hear back from an engineer, not a call centre. For a vessel that is stranded or on a tight departure slot, call +31 6 20743967 or message us on WhatsApp.

Direct line

Vibration, hot bearings or a new engine bed?

Alignment problems destroy couplings, seals and bearings quietly and expensively. Get it measured before the damage spreads.

Superyacht Engine Service — powered by Marine Service Altena B.V.
+31 6 20743967 · info@superyachtengineservice.com
KvK 99330911 · Available for callout across Europe
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