International Journal
on Marine Navigation
and Safety of Sea Transportation
Volume 6
Number 1
March 2012
Although the situation has improved somewhat re-
cently, a series of collisions have occurred in some
Japanese sea routes between hydrofoil-type super
high-speed vessels (hereafter HF vessels”; Fig. 1)
and large marine life and continue to concern
transport officials and other relevant peoples to this
issue. These collisions are often the target of marine
accident inquiries that examine the responsible fac-
tors, and it would be accurate to state that in most
instances, the collisions involve cetaceans (Fig. 2).
Thus, such collisions not only negatively impact safe
navigation, but also represent a risk to the survival
of cetaceans.
Figure 1. Hydrofoil type of high-speed vessel, which are used
for important high-speed sea routes linking remote islands with
the Japanese mainland. (Photograph by H. Kato)
Figure 2. Sperm whale, a whale species with a high collision
risk with hydrofoil-type super high-speed vessels. Their popu-
lation in the waters around Japan has increased in recent years.
(Photograph by H. Kato)
Towards Safer Navigation of Hydrofoils:
Avoiding Sudden Collisions with Cetaceans
H. Kato, H. Yamada, K. Shakata, A. Odagawa, R. Kagami & Y. Yonehara
Tokyo University of Marin Science and Technology (TUMSAT), Tokyo, Japan
M. Terada & K. Sakuma
KHI JPS Co., Ltd., Kobe, Japan
H. Mori & I. Tanaka
Kawasaki Heavy Industries Ltd., Kobe, Japan
H. Sugioka & M. Kyo
Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokohama, Japan
ABSTRACT: Recently, sudden collisions between large cetaceans and high-speed hydrofoils have become
problematic to Japanese sea transport in some localities. We therefore initiated a project to investigate ap-
proaches for minimizing risk to both ships and cetaceans. Under the present project, the following three sub-
projects are underway: clarifying which whale species are found near sea routes and determining their season-
al variations; identifying whale species that have a high collision risk; and determining the unique acoustic
characteristics of high-collision-risk cetaceans for the improvement of underwater speakers (UWS). By con-
ducting acoustic surveys using novel methods, including an anatomical approach based on characteristics of
the inner ear, the aim of this project is to accurately estimate the audible range of species with a high collision
risk and improve the sounds generated by the UWS. Thus far, we have identified the cetacean species at high-
risk in two major sea routes. In the next phase of the study we plan to develop an imaging system that recog-
nizes a cetacean's unique blow using an infrared camera, in an attempt to warn of the approach of high-
collision-risk whale species at an early stage by sounding an alarm.
Beginning around the year 2000 in Europe, the
Agreement on the Conservation of Cetaceans in the
Black Sea Mediterranean Sea and Contiguous Atlan-
tic Area (ACCOBAMS), which is based on the Bonn
Convention on the Conservation of Migratory Spe-
cies of Wild Animals (UNEP/CMS), was formed in
response to increased concerns about collisions be-
tween large cetaceans and ships. In tandem, discus-
sions were also initiated at the International Whaling
Commission (IWC), which is the main organization
for the management of cetacean stocks and whaling
issues. In 2008, at the 60th IWC Annual Meeting
held in Santiago, Chile, cooperation with the Inter-
national Maritime Organization (IMO) was strength-
ened, as proposed by the Netherlands, and this coop-
eration was also promoted at the 61st IWC Annual
Meeting held in June 2009 in Madeira, Portugal.
Under this cooperative effort, both international or-
ganizations organized the Joint IWC-ACCOBAMS
Workshop on Reducing Risk of Collisions between
Vessels and Cetaceans (Anon, 2010).
Against this background, this paper outlines our
research project aimed at reducing risks to both
ships and cetaceans against sudden collisions, par-
ticularly for large cetaceans, and discusses future di-
rections in this field. The main sections of this paper
have been taken from selected sections presented in
a previous paper by Kato (2009).
The IWC, ACCOBAMS, and IMO regard collisions
between large cetaceans and super high-speed ves-
sels as one of significant threats to the survival of
cetaceans. Their main strategies for deterring such
collisions are clear and simple, and involve requiring
HF vessels to settle on the surface and reduce speed
whenever whales appear, and establishing protection
areas for whales. However, as these approaches will
not always prevent collisions, additional research
projects to identify more effective strategies are nec-
Japan, which is completely surrounded by sea,
has a population of approximately 130 million peo-
ple. The Japanese population is predominantly con-
centrated in urban areas, whereas in rural and moun-
tainous areas, extreme depopulation is occurring.
The numerous islands surrounding Japan are no ex-
ception; the depopulation of the once well-
developed islands will devastate them, leading to
environmental damage and disturbances to the coast-
line, which will eventually penetrate the offshore ar-
eas. HF vessel services help limit the depopulation
of the islands, as they drastically shorten the travel
time between them and the mainland, making fre-
quent travel more feasible. However, increases in the
number and frequency of HF vessels on sea routes
poses increased risk for collisions between vessels
and cetaceans. . The main goal of our research pro-
ject is to identify effective approaches for limiting
the risks associated with collisions between large ce-
taceans and HF vessels.
In April 2006, the Maritime Bureau of the Ministry
of Land, Infrastructure, Transport and Tourism es-
tablished a committee for considering safety
measures for HF vessels. The Laboratory for Ceta-
cean Biology at Tokyo University of Marine Science
and Technology, based on the working group estab-
lished by the above-mentioned committee, began
conducting research on collision avoidance by seek-
ing the cooperation of Kawasaki Shipbuilding Cor-
poration, a maker of Jetfoils (JF) which are the main
type of hydrofoil-type HF vessels, KHI JPS Co.,
Ltd., which is in charge of HF vessel maintenance,
and several additional companies, such as Sado
Kisen Co., Ltd., and Tokai Kisen Co., Ltd., which
operate JF services.
A number of HF vessels are equipped with un-
derwater speakers (UWS) that emit sound waves
with the aim of repelling cetaceans. However,
whales (86 species in total; 14 species within the
suborder Mysticeti and 72 species within the subor-
der Odontoceti, as recognized by the Scientific
Committee of the IWC in 2010) differ markedly in
their acoustic characteristics depending on the spe-
cies, particularly between baleen whales, which are
highly adapted to the ocean, and toothed whales,
which have retained numerous traits from their ter-
restrial mammal ancestors (Fig. 3).
Figure. 3 Differences in the sonar frequency bands of cetacean
species grouped at the sub-order level of taxon. Cited literature
for sonar frequencies: Mysticeti (baleen whales), Au, 2000;
Odontoceti (toothed whales), Backus and Schevill, 1966.