ACV Noise and Environmental Impact

 On this page we will gradually assemble reference materials related to noise emissions and other environmental impact, primarily of  amphibious hovercraft.

General Note

Due to amphibious ACV’s using propellers or fans for propulsion they have a noise signature that is generally higher than other marine craft. This may be accentuated by the exhaust note of a 2-stroke engine for smaller craft. Being amphibious, ACV’s have the ability to operate in the inter-tidal area, shallow water river or coastal areas etc. Many of such areas globally are controlled in some way as environmentally protected, specifically limiting or banning recreational activities (most often of all recreational craft, not just hovercraft).

The ACV noise signature in particular can disturb wildlife, and the cushion pressure signature can affect organisms in the mud/sand.

The reference material included here is intended to provide some scientifically collected and assessed data and evaluation. ACV operators should find this helpful if or when considering a coastal, estuarial, or harbour sortie/cruise.

It may be noted that during the early development of hovercraft, the noise signature from  commercial operations and its effect on communities was also a significant issue. Studies related to this are presented below.

In addition to these environmental impact considerations, many countries consider a hovercraft in a similar way to other marine craft, and thus for safe coastal operation a hovercraft would have to be registered in the same way as a power boat with the relevant marine authorities, and the operator is likely to require small boat training from a recognised authority.

In the UK training for recreational small boat operations is run by the Royal Yacht Association and is voluntary rather than being a legal requirement. For commercial operations for example with a RIB or a workboat or hovercraft the operator must have the appropriate RYA qualification and this must be commercially endorsed. 

It should be noted that in the UK the MCA Hovercraft Code is applicable for regulating smaller hovercraft construction and operation. Chapters 24 and 25 provide guidelines for both good practise, and for mandated requirements including the RYA training. These are mandatory for craft being operated commercially and those over 24m length, while for smaller craft operational training and guidelines are given as recommended. The certification in accordance with the guidelines by the approved bodies will then provide proof of a hovercraft and operator safety for local authorities, regulators, and insurance providers.

Hovercraft Noise
UK Noise Advisory Council 1979

Overview

This report was prepared by an advisory group formed by the Noise Advisory Council with the aim to understand the issues several local authorities were having at that time due to significant noise signatures from the open propeller SR.N series craft. Their approach provides a useful template for such investigations. The results had an impact on the design development of amphibious hovercraft as well as their operations.

Contents

  • Summary of Conclusions and Recommendations
  • Introduction
  • The development of Hovercraft
  • The legal Position on the control of hovercraft noise
  • Progress in the reduction of noise from hovercraft
  • Noise from hovercraft in current commercial operations
  • Discussions with manufacturers, operators, and local authorities
  • Findings and views of the Working Group

    Figures 1-5

Other publications of the Noise Advisory Council

Noise Characterisation study of the AP1-88 Hovercraft
Published by US Department of Transportation 1996

Overview

During the period, June 1995 through March 1996, the U.S. Department of Transportation, Research and Special Programs Administration, John A. Volpe National Transportation Systems Center (Volpe Center), Acoustics Facility, in support of the United States Postal Service (Postal Service) Office of Environmental Policy & Management, conducted a Noise Characterization Study of the British Hovercraft Corporation Model AP.1-88 Hovercraft (AP.1-88).

This document presents the results of the study, including the measurement, data reduction and analysis procedures used to characterize the craft. Also presented, for the purpose of comparison with the AP.1-88 noise data, is a limited amount of measured noise data for the Textron Marine & Land Systems Lighter Air Cushion Vehicle-30 (LACV-30) hovercraft.

It should be noted that some diagrams are missing from this copy obtained from the DOT

Contents

  • Introduction
  • Measurement Instrumentation
  • Experimental Approach
  • Data Reduction and Analysis
  • Discussion of Results
  • Conclusions

 

Appendices

A  Proposed Mail Delivery Schedule
B  As-measured data
C  Corrected pass-by data
D  Corrected one-third octave-band spectral data
E  Assessment of community noise impact due to hovercraft
F  Statement of hovercraft configuration
G  References
H  Subject Index

Airborne and Underwater Noise Produced by a Hovercraft in the North Caspian Region; Pressure and Particle Motion Measurements
Alexandr I. Vedenev, Oleg Yu. Kochetov, Andrey A. Lunkov, Andrey S. Shurup and Saltanat S. Kassymbekova

Overview

The measurements of airborne and underwater noise radiated by a Griffon BHT130 hovercraft were conducted in the Ural-Caspian Channel and in the North Caspian Sea. This type of hovercraft is being used for all-season cargo and crew transportation to oil and gas platforms within the environmentally sensitive area of the Ural River estuary known for its abundant bird and fish fauna.

Several field campaigns were organized from 2017 to 2022 to measure and analyze acoustic noise levels simultaneously in the air and underwater at various sites and hovercraft speeds. Airborne noise levels were estimated according to ISO 2922:2020, 2021. Underwater noise study included not only acoustic pressure recordings but also particle velocity measurements with a self-designed pressure gradient sensor (PGS), which is important since the hearing of the majority of fish perceives the sound in terms of particle motion.

This study is the first to report the particle velocity levels formed underwater during hovercraft passages. The minimum levels of underwater noise, 100 dB re 1 µPa (pressure), 45 dB re 1 nm/s (particle velocity), and airborne noise, 93 dBA re 20 µPa (pressure), normalized to a distance of 25 m were observed for the hovercraft passages at a cruising speed of 7–15 m/s. Thus, this speed interval can be recommended as an optimum to minimize an acoustic impact on ornitho- and fish fauna.

The directivity of the hovercraft noise was estimated for the first time and utilized for noise mapping of the Ural-Caspian Channel. The possible hydrodynamic effect of a passing hovercraft is discussed.

Contents

  1. Introduction
  2. Materials and Methods
  3. Discussion and Conclusions

Please Note: The link attached to the front page image above will take you to the document site where you can download the paper . The paper is published as open access under the Creative Commons agreement. Initially published in May 2023, downloads from this site will enable you to see any updates or corrections that may have been made since initial publication

Monitoring the effects of a hovercraft survey in Langstone and Chichester Harbours
Louise MacCallum, Langstone Harbour Board, March 2014

Overview

A report prepared for Langstone Harbour Board, following an environmental survey carried out by a hovercraft.

The reaction of wildlife, particularly wintering waders and wildfowl to a hovercraft engaged in a benthic intertidal survey were monitored within the Chichester and Langstone Harbours Special Protection Area (SPA).

In early 2014 the Environment Agency (EA) requested permission to undertake a scientific benthic intertidal survey in both Chichester and Langstone Harbours utilising a small hovercraft. The object of this survey was to measure benthic invertebrate diversity and quantities to aid in the classification of the harbours under the Water Framework Directive (WFD).

The report documents observations of birdlife and seals to the passing by and presence at the selected physical sampling points.

Contents

Executive Summary
Introduction
Aims
Methodology
The Hovercraft
Results

Conclusions
                Wildlife Response
                Hovercraft as survey tools
                Recommendations

Acknowledgements

Marine Recreation Evidence Briefing : Hovercraft
Natural England Evidence Information Note EIN03

First Edition 27 November 2017

Overview

This briefing note provides evidence of the impacts and potential management options for marine and coastal recreational activities in Marine Protected Areas (MPAs). It is intended to provide an overview of the evidence base and is complementary to Natural England’s Conservation Advice and Advice on Operations which should be referred to when assessing potential impacts.*

The study was commissioned by Natural England and the Marine Management Organisation to collate and update the evidence base on the significance of impacts from recreational activities.

The specific impact of recreational hovercraft is discussed in this note and recommendations for good practise are presented. It should be noted that the significance of any impact on the Conservation Objectives for an MPA will depend on a range of site-specific factors.

This note relates to recreational use of hovercraft in coastal water (cruising). Hovercraft racing has not been included in this note as this is mainly conducted in inland waterways. Other notes are available for other recreational activities, for details see further information in the contents list below.

* The Conservation advice site also links to an interactive map where you can define the area you are interested in and then identify the location specific advice.

Contents

Hovercraft – definition, distribution of activity, levels of activity
Pressures on the environment from recreation activity
Impacts of hovercraft activity
Assessment of risk of significant impact
Management Options
National Governing Body and Good Practise Messaging
Further Information

References