Case study · Marine engineering - A marine engineering shop and the 16× noise dose
A real, anonymised assessment of a marine-engineering shop — and a hammering station carrying sixteen times the daily noise limit.
Impact Acoustics · updated 10 Aug 2026 · 5 min read
The site
A marine-engineering manufacturer on the South Coast, with paint and spray shops, a machine shop and fabrication cells including hand-finishing and hammering. We assessed twenty-five task and area positions on an 8-hour basis and grouped them into paint, fabrication, machine-shop and ancillary exposure groups.
What we found: marine engineering at 97.1 dB(A)
Real measured daily personal noise exposure (LEP,d) by work area, from an anonymised recent assessment. Values above 85 dB(A) are Hearing Protection Zones.
Seven positions sat at or above the 85 dB(A) upper action value, led by a hand-hammering station at 97.1 dB(A), with the paint flatting bay, spray booths and electrical spray shop close behind, and six more between 80 and 85 dB(A). As at many engineering sites, the peaks stayed under the 135 dB(C) action value (highest 115.9 dB(C)).
The insight that pays for the survey
The hammering station tells the story. A full shift there generates roughly 1,600 HSE exposure points — about sixteen times the daily upper action value — and an unprotected worker reaches the 85 dB(A) limit in under half an hour. Yet nothing on site produced a dramatic impulse peak. That’s the trap in judging noise by ear: the danger here was slow, cumulative dose from steady and intermittent work — precisely the exposure that ‘it’s not that loud’ and hearing-protection-only thinking underestimates.
What the client got
- Mandatory Hearing Protection Zones across the seven areas over the upper action value, with the existing protectors checked (SNR 15–25, real-world de-rated) so the level at the ear stays under the limit.
- A source-control review for the hammering station first — damping, workpiece support, alternative tooling and local shielding — where the biggest dose reduction sits.
- Role-based exposure profiles from real task durations, and audiometry for the staff regularly at or above the upper action value.
That is the difference between a survey that just says “you’re over the limit” and one that tells you exactly where to act — and keeps it current, which is what the 4-Year Care Plan is for.
Not sure where your site stands?
Take the free 60-second check, or talk to us about the 4-Year Care Plan.