How Loud Is the MARCO PW3 Air Horn? 132 dB Marine Whistle for Vessels 20-75 m
Updated: 5 hours ago
When choosing a marine air horn for a yacht or commercial vessel, sound performance is only part of the decision. The equipment also needs to meet the relevant maritime regulations, work with the vessel's onboard systems and be supported by reliable technical documentation.
The MARCO PW3 nautical whistle, manufactured in Italy by MARCO S.p.A., is a pneumatic marine horn designed for vessels from 20 to less than 75 metres in length.
Available in separate 12V and 24V versions, the PW3 delivers a manufacturer-specified sound pressure level of 132 dB at 1 metre, operates at a frequency of 315 Hz and is designed to meet the acoustic requirements of COLREG 1972 Annex III, IMO Class III.
But what makes the MARCO PW3 different from a conventional boat horn, and why do its technical specifications and marine approvals matter?
Table of Contents:
What Does the MARCO PW3 Air Horn Sound Like?
A marine air horn does more than produce a loud warning sound. It provides an important means of communication between vessels, particularly when visibility is restricted or navigation takes place in busy waterways.
The MARCO PW3 air horn sound is produced by a pneumatic whistle mechanism operating with compressed air. Its specified frequency of 315 Hz provides a defined acoustic characteristic, while the sound pressure level reaches 132 dB at 1 metre, measured in a one-third-octave band.
These figures are important because marine sound signalling equipment must meet acoustic requirements appropriate to the vessel's length.
The PW3 is not simply designed to sound loud. Its acoustic characteristics are specified for a particular category of vessels under international maritime regulations.
Want to hear the MARCO PW3?
Listen to the sound example in the video above or visit the official MARCO PW3 product page.
A recording can demonstrate the character of the sound, but its playback volume cannot reproduce the actual 132 dB sound pressure level.
MARCO PW3 and COLREG 1972 – What Are IMO Class III Requirements?
One of the most important features of the MARCO PW3 is its intended compliance with international maritime sound signalling requirements.
The International Regulations for Preventing Collisions at Sea (COLREG 1972) establish rules for navigation safety, including the use and technical characteristics of sound signalling appliances.
Under Annex III, whistles intended for vessels from 20 to less than 75 metres in length must meet the following acoustic requirements:
Vessels 20 to less than 75 m | |
Minimum sound pressure level | 130 dB at 1 m |
Specified frequency band for determining audibility | 180–700 Hz |
Nominal audibility range | 1 nautical mile |
Applicable equipment category | Marine sound signalling whistle |
The MARCO PW3 has a manufacturer-specified acoustic output of 132 dB at 1 metre in a one-third-octave band, compared with the minimum regulatory requirement of 130 dB.
Its frequency of 315 Hz also falls within the prescribed band.
An important distinction: the designation 20–75 m refers to vessel length, not the distance at which the horn can be heard.
The nominal audibility range of one nautical mile is defined under specified conditions. Actual sound propagation depends on atmospheric conditions, background noise and installation.
For vessels 20 metres or longer, COLREG Rule 33 generally also requires a bell in addition to the whistle. Choosing a compliant whistle is therefore one part of meeting the vessel's overall sound signalling obligations.
MARCO PW3 Technical Specifications – 12V vs 24V Marine Horn
The PW3 is available in two electrical configurations. Both versions have the same published acoustic performance, but different current requirements and MARCO part numbers.
The 12V and 24V versions are separate products, rather than a single dual-voltage unit.
When replacing an existing marine horn, check both the electrical supply and the MARCO part number before ordering.
How Does the MARCO PW3 Pneumatic Marine Air Horn Work?
Unlike a conventional electric boat horn, the MARCO PW3 generates its sound using compressed air.
An electrically operated solenoid valve controls the air supply to the horn. When the valve is activated, compressed air enters the whistle mechanism and produces the acoustic signal.
The standard PW3 product includes the horn, electric valve and mounting accessories for installation in a compatible onboard pneumatic system.
However, there is an important requirement to consider before purchasing:
The MARCO PW3 requires an external compressed-air supply operating at 6–12 bar.
If the vessel does not already have a suitable pneumatic system, an additional compressor and air tank may be needed.
MARCO offers the M3 compressor with an 8-litre air tank as a compatible accessory, along with pneumatic tubing and other installation components.
For boatbuilders and marine engineers, checking the air supply at the planning stage helps avoid selecting an otherwise suitable whistle without the equipment necessary to operate it.
Why Choose the MARCO PW3 Marine Air Horn? Certified Performance and Reliability
For a commercial vessel, yacht or professional marine installation, choosing a pneumatic whistle means considering more than its appearance or sound level.
The MARCO PW3 offers a combination of defined acoustic specifications, independent design assessment and manufacturer-supported installation guidance.
Designed for International Marine Sound Signalling Requirements
The PW3 is specifically designed for the acoustic requirements of vessels from 20 to less than 75 metres, rather than for general-purpose warning signals.
Its published 132 dB sound pressure level and 315 Hz frequency provide measurable characteristics that can be compared with COLREG Annex III requirements.
This makes it easier for vessel owners, marine installers and technical purchasers to assess whether the PW3 is suitable for their intended application.
RINA Prototype Design Assessment – Independently Documented Performance
One of the strongest reasons to consider the MARCO PW3 is its supporting certification documentation.
RINA Services S.p.A. issued Prototype Design Assessment Certificate No. ELE333323CS for MARCO PW2 and PW3 ship's whistle designs.
The certificate was issued on 30 October 2023 and states a validity period until 29 October 2028, subject to its conditions.
The accompanying documentation identifies the PW3's intended vessel-length category and includes references to acoustic measurements, technical drawings and applicable international regulations.
For marine equipment buyers, this provides a valuable distinction: the product design has been assessed through a recognised independent marine certification process, rather than relying solely on manufacturer claims.
The certificate is a prototype design assessment. It does not automatically constitute approval of every individual installation.
Lloyd's Register, Bureau Veritas and German BSH – A Documented Approval History
MARCO's published technical documentation also includes previous approval records associated with Lloyd's Register MCA and Bureau Veritas.
These documents concern the PW3 ship's sound signalling equipment and refer to maritime requirements, testing and installation conditions.
The manufacturer documentation additionally contains a historical acceptance from the German Federal Maritime and Hydrographic Agency (BSH) for the PW2/PW3 type, relating to use on German-flagged vessels.
These records demonstrate that the PW3 design has been evaluated within several maritime approval frameworks.
However, certification documents have individual validity periods and conditions. The supplied Lloyd's Register MCA and Bureau Veritas certificates have expired, so updated approvals should be requested where these are required for a new installation.
For vessels subject to formal surveys or classification requirements, it is always advisable to confirm the latest applicable documentation with MARCO and the relevant flag-state administration or classification society.
A clarification about IMO and European certification: IMO establishes international maritime requirements but does not issue an individual PW3 product certificate. Likewise, conformity with COLREG should not be confused with EU MED Wheelmark certification.
Suitable for 12V and 24V Marine Electrical Systems
The PW3 family includes separate 12V and 24V versions, making it possible to select a model compatible with the vessel's onboard electrical supply.
Both versions deliver the same published acoustic performance.
The electric solenoid valve provides a practical means of controlling the pneumatic signal through the vessel's electrical system, subject to the manufacturer's installation instructions.
Installation and Maintenance Documentation
An important advantage of the PW3 is the availability of detailed manufacturer documentation.
MARCO provides electrical connection instructions, mounting diagrams and an exploded assembly drawing identifying the internal components.
These include the diaphragm, O-rings, springs, fittings and other parts of the whistle assembly.
Having this information available helps marine technicians understand the equipment, plan inspections and identify components when maintenance is necessary.
The manufacturer manual also specifies a two-year limited warranty against manufacturing defects, subject to its published conditions.
Different Finishes for Different Vessel Designs
The MARCO PW3 family is available in standard, chromed, white and black versions.
This gives boatbuilders, yacht owners and commercial vessel operators a choice of exterior finishes while retaining the same published nominal acoustic performance.
The variants also differ in their overall dimensions, so appearance and available mounting space should both be considered.
Why These Features Matter
The MARCO PW3 offers something particularly valuable for professional marine applications: technical characteristics that can be checked against established requirements, supported by documented design assessment and manufacturer installation guidance.
For buyers who need to assess a nautical whistle before ordering, these details provide a stronger basis for a purchasing decision than sound level or appearance alone.
MARCO PW3 Series Comparison – PW3, PW3-BC, PW3-BB and PW3-BN
Choosing the right PW3 variant depends on the vessel's electrical supply, preferred finish and available installation space.
All four variants have the same published nominal acoustic output of 132 dB at 1 metre and frequency of 315 Hz.
The dimensions above follow MARCO's online product listings. As catalogue tables and dimension drawings may differ between revisions, installers should verify the latest drawing for the exact part number before drilling mounting holes.
For an existing installation, checking the original model reference is usually the most straightforward starting point.
MARCO PW3 Installation – What Should You Check Before Ordering?
A suitable marine air horn must work with the vessel's actual electrical and pneumatic systems.
Before ordering the PW3, we recommend checking the following points:
Vessel length: Confirm that the vessel falls within the 20 to less than 75 metre category.
Electrical supply: Select the correct 12V or 24V version and follow the manufacturer's wiring and circuit-protection instructions.
Compressed-air system: Confirm that a suitable air source can provide the required 6–12 bar operating pressure.
Mounting position: MARCO recommends a slight downward inclination of approximately 5° to help prevent water collecting inside the horn.
Tubing and fittings: Check the specified pneumatic connection and the routing of the air line.
Access for maintenance: Allow room for inspection of the horn, valve and associated connections.
Approval requirements: For regulated commercial vessels, confirm the relevant flag-state and classification requirements.
A small installation detail can make a practical difference. For example, the recommended downward inclination helps reduce the risk of water remaining inside the horn.
MARCO's manual also explains that small impurities reaching the diaphragm can interfere with operation. Maintenance and inspection should therefore follow the manufacturer's instructions.
Frequently Asked Questions About the MARCO PW3 Air Horn
How loud is the MARCO PW3 marine air horn?
The PW3 has a manufacturer-specified sound pressure level of 132 dB at 1 metre, measured in a one-third-octave band, and a frequency of 315 Hz.
These are technical measurement values. The actual perceived sound depends on distance, surroundings and environmental conditions.
What does 20–75 m mean for the MARCO PW3?
It refers to the length of the vessel, not the horn's audible distance.
The PW3 is designed for vessels from 20 to less than 75 metres in length under the relevant COLREG acoustic category.
Can the MARCO PW3 be used on a vessel exactly 75 metres long?
A vessel measuring exactly 75 metres falls into the next COLREG acoustic category, with different requirements.
The PW3 should not be selected for that vessel solely on the basis of its 20–75 m product designation.
Is the MARCO PW3 an IMO-certified marine horn?
The PW3 is designed to meet COLREG 1972 Annex III requirements, which are established within the IMO framework.
IMO does not issue a PW3 product certificate. Independent design assessment documentation is provided by organisations such as RINA.
Does the MARCO PW3 have RINA approval documentation?
Yes. The MARCO PW3 design is covered by RINA Prototype Design Assessment Certificate No. ELE333323CS, issued on 30 October 2023 and stating validity until 29 October 2028, subject to its conditions.
The certificate covers the PW2 and PW3 ship's whistle designs and references the relevant COLREG requirements. For installations requiring formal approval, the latest applicable documentation should be confirmed with MARCO or the vessel's classification society.
Does the MARCO PW3 include an air compressor?
The standard product description lists an electric valve and mounting accessories. A suitable external compressed-air supply is necessary for operation.
If the vessel does not have an appropriate air system, a compatible compressor and tank must be considered separately.
Should I choose the MARCO PW3 12V or 24V?
Choose the version that matches the vessel's onboard electrical supply.
Both versions have the same published acoustic output, but the 12V version has a maximum current draw of 4.5 A, compared with 2.5 A for the 24V version.
Is the MARCO PW3 suitable for commercial vessels and yachts?
The PW3 is intended for the specified vessel-length category and can be considered for appropriate professional marine applications.
Final suitability depends on the vessel's dimensions, installation, applicable regulations and any required flag-state or classification approvals.
Buy MARCO PW3 Marine Air Horns 12V/24V in Germany and Europe
Looking to buy an original MARCO PW3 marine air horn, replace an existing nautical whistle or find the right pneumatic sound signalling system for your vessel?
EES Energie-Erzeugung-Systeme GmbH, an official distributor of MARCO S.p.A. in Germany, supplies original MARCO marine horns, accessories and spare parts to customers across Germany and Europe.
We support enquiries from major European maritime markets, including Germany, the Netherlands, Belgium, France, Italy, Spain and Greece.
Whether your vessel is based in Hamburg, Rotterdam, Antwerp, Marseille, Genoa, Barcelona or Piraeus, our team can assist with product selection, order enquiries and compatible accessories.
Our range includes the MARCO PW3 12V and 24V, together with PW3-BC, PW3-BB and PW3-BN variants and compatible pneumatic equipment.
Need Help Choosing the Right MARCO PW3?
Not sure which model or accessories your vessel requires?
Tell us your vessel's length, onboard voltage and whether a compressed-air system is already installed. These details will help us identify the appropriate configuration.
We can also assist with manufacturer technical documentation and enquiries about applicable approval records.
EES Energie-Erzeugung-Systeme GmbH
Berlin, Germany
Phone: +49 30 70016272
Email: contact@eesystem.de
Original MARCO marine equipment, technical product guidance and European delivery enquiries.
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