Guide 02 Quality assurance and type approval
What do vibration, bump and inclination tests check on shipboard equipment?
Vibration, bump and inclination tests each reproduce a different physical condition a ship exposes its equipment to: continuous machinery vibration, sudden mechanical shocks such as gunfire or slamming, and the list, roll and pitch angles a vessel can take up at sea. All three are common entries in a JSS 55555 qualification schedule.
- Topic
- Quality assurance and type approval
- Checked
- 23 September 2026
- Sources
- 4
- Questions
- 5
01
Vibration: continuous running conditions
A vibration test reproduces the steady shaking a ship's own machinery, propellers and sea state impose on everything mounted aboard it. Naval shipboard equipment is commonly vibration tested over a 5 to 33 Hz range, the band EED-Q-071 cites in line with JSS 55555, though minor war vessels can call for a wider range, such as 7 to 300 Hz, in their own specification.
The DGQA laboratory at CQAE (WE), Bangalore, lists its vibration test as constant displacement, swept manually across the frequency range and then held at fixed frequencies for an endurance period. A published qualification schedule for a naval power supply records its vibration test at 5 to 33 Hz, 0.125 millimetre constant displacement, run on the x, y and z axes.
02
Bump: repeated mechanical shocks
A bump test applies many short mechanical shocks in succession rather than the single severe event a shock test uses. It stands in for handling, transport and the repeated jolts of a working ship rather than for underwater explosion. A published qualification schedule records its bump test as 1,000 bumps, plus or minus 10, at 40g, each 6 milliseconds long.
03
Inclination and tilt: the angles a ship takes up
An inclination or tilt test checks that equipment still starts and runs correctly at the list, roll and pitch angles a ship can take up, not only when sitting level on a bench. NES 1004, a UK Ministry of Defence naval engineering standard for environmental conditions, is one of the documents naval specifications cite for this requirement; the exact angle still comes from the equipment's own specification.
As a worked example, EED-Q-071 requires naval motors to operate at a permanent list of 30 degrees, a roll of plus or minus 30 degrees and a pitch of plus or minus 15 degrees, tested in whichever direction is most severe for the equipment. A published qualification schedule for a naval power supply lists an inclination and tilt test to NES 1004 at 15 degrees for normal operation and 30 degrees for survival.
Three tests, three conditions they stand in for
- Vibration
- Continuous machinery and sea-induced shaking during normal running
- Bump
- Repeated mechanical shocks from handling, transport and rough service
- Inclination and tilt
- The list, roll and pitch angles a ship takes up at sea
04
Why a motion simulator is used as well
A ship's list, roll and pitch move oil levels inside a gearbox, shift bearing loads, can close or open relay contacts and change how liquid sits in a battery or a tank, none of which shows up on a test bench sitting level. A ship motion or tilt table reproduces those angles so problems such as oil starvation or a spurious trip appear during qualification rather than at sea. The DGQA laboratory at CQAE (WE), Bangalore, lists a ship motion table rated to plus or minus 15 degrees.
Asked next
Questions people also ask
What do vibration, bump and inclination tests check on shipboard equipment?
What frequency range is used for naval vibration testing?
Naval shipboard equipment is commonly vibration tested over 5 to 33 Hz, the range EED-Q-071 cites in line with JSS 55555, at constant displacement swept across the range and then held at fixed frequencies for endurance. Minor war vessels can call for a wider band, such as 7 to 300 Hz, so the applicable range still depends on the item's own specification.
What is the difference between a bump test and a shock test?
A bump test applies many moderate mechanical shocks in succession, such as 1,000 bumps at 40g, to reproduce handling, transport and routine rough service. A shock test applies a small number of much larger pulses, such as an NSS Grade I shock, to reproduce a single severe event like an underwater explosion near the ship.
What angles does an inclination test cover?
Angles are set by the equipment's own specification rather than by a single fixed rule. As one example, the Indian Navy's motor specification EED-Q-071 requires operation at a permanent list of 30 degrees, roll of plus or minus 30 degrees and pitch of plus or minus 15 degrees, tested in the direction most severe for the item.
What is NES 1004?
NES 1004 is a UK Ministry of Defence Naval Engineering Standard covering requirements for the design and testing of equipment against environmental conditions, including ship motion and inclination. Naval specifications cite it for these conditions, but the exact test values come from the edition in use together with the equipment's own specification, so both need to be read.
Why is a ship motion simulator used if vibration and inclination are already tested?
Because a static inclination test and a running vibration test do not reproduce a moving list, roll and pitch together. A motion or tilt table exposes problems such as oil starvation in a gearbox or a spurious relay trip that only appear while the equipment is tilted and running at the same time, which is closer to how it will actually operate at sea.
Checked against
Sources
- 01Guidelines for Environmental Testing at CQAE (WE), Bangalore, Directorate General of Quality Assurance
- 02NES 1004, Issue 2, Requirements for Design and Testing of Equipment, UK Ministry of Defence, standard listing
- 03Inclination Testing for Marine Industry Equipment, Element Materials Technology
- 04Directorate of Quality Assurance (Naval), Indian Navy
This guide explains how the system works in general, as the documents above describe it, and was last checked on 23 September 2026. Rules and thresholds change: the governing document is the authority, not this page.
On this site
Where this meets the work
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- The DQA(N) type approved battery charging rectifier
- The marine engineering division
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