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Docket #:2021-01

This proposal has been submitted for review.

To the proposer’s knowledge, is this achievement subject to litigation? No

Is the achievement you are proposing more than 25 years old? Yes

Is the achievement you are proposing within IEEE’s designated fields as defined by IEEE Bylaw I-104.11, namely: Engineering, Computer Sciences and Information Technology, Physical Sciences, Biological and Medical Sciences, Mathematics, Technical Communications, Education, Management, and Law and Policy. Yes

Did the achievement provide a meaningful benefit for humanity? Yes

Was it of at least regional importance? Yes

Has an IEEE Organizational Unit agreed to pay for the milestone plaque(s)? Yes

Has an IEEE Organizational Unit agreed to arrange the dedication ceremony? Yes

Has the IEEE Section in which the milestone is located agreed to take responsibility for the plaque after it is dedicated? Yes

Has the owner of the site agreed to have it designated as an IEEE Milestone? Yes

Year or range of years in which the achievement occurred:

1948: ‘1948’ is the year when the fishfinder was commercialized for the first time by Furuno Electric Co., Ltd.

Title of the proposed milestone:

Commercialization of the Fishfinder, 1948.

Plaque citation summarizing the achievement and its significance:

A fishfinder, commercialized for the first time by Furuno Electric Co., Ltd. in 1948, reformed the fishery industry in Japan and contributed remarkably to the development of protein resources. This fishfinder was realized by improving an echo sounder so that it could catch clearly the weak echo signals reflected from fish schools by enhancing the ability of its built-in amplifier.

200-250 word abstract describing the significance of the technical achievement being proposed, the person(s) involved, historical context, humanitarian and social impact, as well as any possible controversies the advocate might need to review.

The fish finder is a device that transmits ultrasonic waves into the water and receives the reflected waves to visualize and detect fish schools. The Japanese brothers Kiyotaka and Kiyokata Furuno commercialize the fish finder that can reliably detect fish schools. They improve the reception amplifier of the acoustic sounder that was used for surveying sea depth to detect the weak reception signal reflected by fish school, and they devised equipment methods such as drilling holes in the bottom of a wooden ship for installing an ultrasound transducer to avoid noise caused by bubbles around the ship. The developed fish finder succeeded in accurately detecting sardine fish school in 1948, dramatically improving the catch and rapidly spreading as an indispensable equipment for fishing. The improved catch helped to secure Japan's protein resources, which had been in short supply after World War II, and contributed to the stability of Japanese life. Today, fish finders are equipped on almost every fishing boat in the world. The invention of the fish finder has an extremely important historical value in that it has brought about a revolutionary change in fisheries by giving a "scientific eye" to fisheries that had previously relied solely on the intuition and experience of fishermen, and electrical technology has brought about the modernization of the fisheries industry.

IEEE technical societies and technical councils within whose fields of interest the Milestone proposal resides.

IEEE Oceanic Engineering Society

In what IEEE section(s) does it reside?

IEEE Kansai Section

IEEE Organizational Unit(s) which have agreed to sponsor the Milestone:

IEEE Organizational Unit(s) paying for milestone plaque(s):

Unit: IEEE Kansai Section
Senior Officer Name: Yutaka Hata

IEEE Organizational Unit(s) arranging the dedication ceremony:

Unit: IEEE Kansai Section
Senior Officer Name: Yutaka Hata

IEEE section(s) monitoring the plaque(s):

IEEE Section: IEEE Kansai Section
IEEE Section Chair name: Yutaka Hata

Milestone proposer(s):

Proposer name: Isao Shirakawa
Proposer email: Proposer's email masked to public

Proposer name: Yasushi Nishimori
Proposer email: Proposer's email masked to public

Proposer name: Takeshi Fujii
Proposer email: Proposer's email masked to public

Please note: your email address and contact information will be masked on the website for privacy reasons. Only IEEE History Center Staff will be able to view the email address.

Street address(es) and GPS coordinates in decimal form of the intended milestone plaque site(s):

Furuno Electric Co., Ltd. : Address: 9-52 Ashihara-cho, Nishinomiya, 662-8580 Japan; GPS coordinates: N 34.741282, E 135.354547

Describe briefly the intended site(s) of the milestone plaque(s). The intended site(s) must have a direct connection with the achievement (e.g. where developed, invented, tested, demonstrated, installed, or operated, etc.). A museum where a device or example of the technology is displayed, or the university where the inventor studied, are not, in themselves, sufficient connection for a milestone plaque.

Please give the address(es) of the plaque site(s) (GPS coordinates if you have them). Also please give the details of the mounting, i.e. on the outside of the building, in the ground floor entrance hall, on a plinth on the grounds, etc. If visitors to the plaque site will need to go through security, or make an appointment, please give the contact information visitors will need. The entrance hall of Furuno Electric Co., Ltd.

Are the original buildings extant?

The original building is extant and belongs to Furuno Electric Co., Ltd.

Details of the plaque mounting:

The plaque will be displayed at the entrance hall of Furuno Electric Co., Ltd.

How is the site protected/secured, and in what ways is it accessible to the public?

The plaque will be displayed in a showcase at the entrance hall of Furuno Electric Co., Ltd., which can be accessible to the public.

Who is the present owner of the site(s)?

Mr. Yukio Furuno, President of Furuno Electric Co., Ltd.

What is the historical significance of the work (its technological, scientific, or social importance)? If personal names are included in citation, include justification here. (see section 6 of Milestone Guidelines)

Historical Significance


In the World War II almost all cities in Japan were reduced to ruins, and the Japanese were forced to suffer from food shortage so severely that the development of food resources grew to be one of the most urgent issues in postwar Japan.

The conventional method of fishing is uncertain in that it relies on the fisherman's intuition and experience to search for fish school by taking cues such as the place where birds flock and the tidal current.


During World War II and in the postwar period, Kiyotaka Furuno was engaged in installation and repair of power generators for fish luring lights of fishing boats. He thought that the fishing industry was the furthest behind in terms of technology.

Furuno wanted to modernize the unstable fishing industry that relies solely on luck and intuition. He aspired to develop a fish finder that could directly find fish school, determine fish species, volume of the fish school, depth from the sea surface and direction of movement of the fish school.

Idea for practical fish finder

Furuno considered applying the ultrasonic technology for determining the location of fish. He found an echo sounder among the navy’s surplus goods and started experiments using it. He found that an echo sounder that is used for detecting depth of the sea, can only receive strong ultrasonic echo from sea bottom, and any echo signal reflected from fish schools was too weak to detect by the echo sounder.

Hence, he determined to improve the built-in amplifier of an echo sounder so that the weak echo signals reflected from fish schools could be clearly caught. The fish finder modified the reception amplifier of echo sounder was so sensitive that it inevitably suffered from influence of various noises. Especially the noise caused by bubbles around running ship influence the fish finder. In order to avoid these noises, he installed the transducers of the fish finder on bottom of ship hull by drilling wooden ship. The fish finder, which was no longer affected by bubble due to the transducer installed on the bottom of the ship, was able to locate schools of fish one after another. Furuno worked together with fishermen to accumulate data of record of fish finder to obtain the knowledge to determine the species of fish from the records recorded by fish finders. Additionally, Furuno simplified the recording mechanism of fish finder to manufacture at low cost and popularize them.

Historical Significance

In October of the year after the fish finders went on sale (1949), all the fishing boats at Iwaseura village were equipped with the fish finder. In November 1949, while the largest catch of the fleet of Narao village, which was not equipped with any fish finder, was 11000 boxes and the smallest was 500 boxes, the largest catch at Iwaseura was 33000 boxes and the smallest was 13000 boxes. The effectiveness of the fish finder was obvious. This success led to the spread of fish finders from Nagasaki Prefecture to all over Japan and the world. The release of fish finder has made it possible to efficiently find schools of fish without relying on fishermen's experience, and the amount of fish caught has increased dramatically. Almost all fishing boats in the world now install the fish finders for finding fish school. As a result, the release of fish finder greatly contributed to expanding the world's fish catch. In this respect, I think it has great social impact and historical value [4][5][6][7][8].

Figure 1 furuno revised.jpg

What obstacles (technical, political, geographic) needed to be overcome?

Obstacles to overcome

Furuno’s business on the fish finder was faced with a number of obstacles, which were overcome as outlined below [8].

Enhancing the amplification of the built-in amplifier

The basic configuration of a fish finder is almost the same as that of an acoustic sounder, as shown in Figure 2.

Figure 2 1 furuno revised.jpg

Fig.2 Structure of a fish finder

Transducer of fish finder consists of a transmitter and a receiver. Electric pulses are applied to the transmitter to send ultrasonic pulses down into the water, and the reflected pulses from schools of fish or the sea bottom are received by the receiver. The received signal passes through an amplifier and enters the recorder. The recorder was composed of a pen applied the signal rectified by rectifiers and recording paper that is mechanically fed out endlessly. A pen moves linearly or circularly at a constant speed over recording paper that is gradually fed out, and when a voltage is applied between the pen and a metal plate on the back of the paper, the paper develops color. The recording paper develops color at the spot corresponding to the target, so the depth to the target object can be determined according to the following formula.


D: Distance from the transducer to the target object [m],

V: Velocity of sound in water (about 1500m/s),

T: Time interval from transmission to reception[s].

Different from the echo sounder intended for detecting the sea depth by reflected echo signals from sea bottom, the fish finder must detect fish schools by receiving much weaker echo signals reflected by fish. Furuno noticed that the reflected signal from fish school of sardine could be caught by raising the amplification by 20 dB, as can be seen from Fig. 3. (Please note that in Figure 3, the x-axis is the distance between the target and the transducer, and the y-axis is the received intensity of the reflected wave from the target.)

In Figure 3, the echo sounder Furuno obtained from Japanese Navy was designed to detect the seabed at a depth of 200 m, and it could detect ultrasonic waves with a sound pressure of 135 dBuPa (as shown by blue line) from the seabed at a depth of 200 m ((a) of Figure 3). For this reason, large fish such as cod could be detected even at a depth of 100 m ((b) of Figure 3), but small fish such as sardines could only be detected at shallow depths of around 20 m ((c) of Figure 3).

Making the sensitivity of the echo sounder increased by 20 dB, it would be able to receive ultrasonic waves with a sound pressure of 115 dBuPa (as shown by red line), and it would be possible to detect common sardines swimming at a depth of 200 m ((d) of Figure 3) on the continental shelf. It was sufficient as a fish finder. (Note that “dBuPa” is unit for ultrasonic relative intensity when 1uPa(=10^(-6)Pa) as 0dB.)

Therefore, Furuno enhanced the amplification of the built-in amplifier by adding the vacuum tube.

By modifying the receiving amplifier, it was possible to display fish images when the fishing boat was not sailing. However, the problem remained that when the fishing boat was running, it was buried in the noise and the fish could not be seen [4][5][8].

Figure 2 furuno revised 3.jpg

fig.3 Intensities of echo signals (pulse width: 1ms) reflected from sea bottom and fish schools of codfishes/sardines.

Installing a transducer on the bottom of the ship to reduce noise

Due to the high sensitivity of fish finders installed on fishing boats, there was a problem in that they picked up various noises that were actually generated by fishing boats as they sailed. Sometimes the recording paper on the display went black due to noise, making it impossible to distinguish fish school echoes.

There were various sources of noise inside the narrow fishing boat, including the engine, pump, and electrical wiring for the fishing lights. Furuno identified the causes of these noises one by one and took steady measures such as moving the transducer away from the noise source and shielding the electrical wiring.

The most difficult noise to counteract was the noise caused by the bubbles that surrounded the ship as the bow of the ship cut through the water. The fish finder's transducer was picking up the ultrasonic waves generated when the bubbles burst. Additionally, when bubbles flowed into the bottom of the transducer, the bubbles obstructed the transmission and reception of ultrasonic waves, significantly reducing the transmitting strength and receiving sensitivity of the fish finder. As the ship speed increased, the effect of the bubbles became even more severe.

Initially, fish finder transducers had a structure in which the transducer was housed in a metal tank filled with water, which was raised and lowered from the side of the boat.

Furuno Electric has devised a method to mount a transducer directly on the bottom of the ship as a drastic solution to the noise caused by bubbles. The effect of bubbles can be avoided by installing the transducer so that it protrudes from the bottom of the ship.

While many fishermen were reluctant to drill a hole in the bottom of a fishing boat, Mr. Tomiichiro Masuda, the owner of fishing boat named the Masutomi Maru, which was suffering from the lowest fishing volume at Iwaseura fishing port in the Goto Islands, agreed to the construction, and in 1949 Work on the bottom of the Masutomi Maru was carried out during the rainy season when fishing was not carried out.

Masutomi Maru's fish finder, which is no longer affected by bubbles thanks to its bottom equipment, was able to locate schools of sardines one after another, and Masutomi Maru recorded the highest catch at Iwaseura Fishing Port from August to October.

Thanks to this success, the effectiveness of the fish finder was recognized by other fishermen. In October 1949, all the fishing boats at Iwaseura were equipped with the fish finder. In November 1949, while the largest catch of the fleet of Narao, which was not equipped with any fish finder, was 11000 boxes and the smallest was 500 boxes, the largest catch at Iwaseura was 33000 boxes and the smallest was 13000 boxes [7][8].

Improvements from military to civilian equipment

With the aim of improving the accuracy and usability of ultrasonic recorders, Kiyotaka Furuno developed and adopted a new belt-type recording mechanism (Japanese Utility Model Publication No. S26-11467). Initially, fish finders were either a circular-arc type or a linear reciprocating type, where a pen moved back and forth on a groove specially cut on a roller. A new belt-type recorder was designed in such a way that the pen attached to the belt moved at a certain speed in a certain direction to make a record. In comparison with conventional fish finders, the new type did not easily break down and its cost was lower [8].

Furuno Electric researched efficient fishing methods using fish finders with fishermen.

In order to expand the market, Furuno Electric worked with fishermen to investigate methods of fishing using fish finders. By analyzing data from fish finders, Furuno discovered that, for example, each species of fish has a tendency to disperse or gather together depending on the time of day. By clarifying the characteristics of each fish species, such as their tendency to cluster or disperse, and the depth of their swimming, fishing can now be carried out more efficiently.

Figure 4 0 furuno revised.jpg

fig.4 Record of fish schools (1950s, Tsushima)

For example, fishermen could use fish finders to distinguish between sardines and horse mackerel. Schools of sardines are recorded as dots on the upper layer, while schools of horse mackerel are recorded as pyramids near the bottom of the ocean shown in Figure 4.

In the case of sardines, when large schools of fish are caught in nets at once, the sardines get stuck in the nets, making it difficult to clean the nets after catching them, and in severe cases, the nets tear due to the weight of the sardines. The fishermen used a fish finder to confirm whether it was sardines or horse mackerel, and also determined the size of the school of fish and adjusted the amount of net wrapping to avoid tearing the net.

In this way, the fish species were determined from the records recorded by the fish finder, and fishing methods were devised to suit the fish species.

Obstacles and solutions for starting a business.

Just after the establishment of Furuno Electric Co., Ltd. the first obstacle falling on their business was fishermen’s insufficient understanding on the fish finder. Hence, Furuno soon edited a booklet on behavior of fish schools (figure 5), and by using this they endeavored earnestly to inform fishermen how to utilize the fish finder for detecting fish schools in actual fishing. The booklet included fish finding records obtained from fishing boats that were useful to identify fish species, understand the ecology of fish schools, and improve fishing gear.

Figure 4 1 furuno revised.jpg

fig.5 a Furuno’s booklet on behavior of fish schools

For example, in the record of Ishikawa Prefecture, Japan in Figure 6, the fish record of school of Tarume is reflected in a place far from the seabed, and the fish record of Chibiki can be identified because it is reflected closely on the seabed.

Figure 4 2 furuno.jpg

fig.6 Record of fish schools (1950s, Noto)

As shown in Figure 7, the record of Niigata, schools of bream are characterized by being triangular or square shaped, darkly colored fish shadows that stick closely to the seabed.

Figure 4 3 furuno.jpg

fig.7 Record of fish schools (1950s, Niigata)

The white line on the ocean floor in Figures 6 and 7 is a function called "White Line" developed by Furuno. This function allows fish that are close to the ocean floor to be displayed separately from the ocean floor and has become an essential feature for fishing that targets fish near the ocean floor, such as bottom trawling. (Japanese Patent S31-3583)

Furuno was successful in increasing the number of users of fish finders through their simultaneous efforts of providing information as described above and spreading the use of fish finders [7][8].

What features set this work apart from similar achievements?

Features set this work apart from similar achievements

Prior art

In Britain, an echo sounder was commercialized in 1933 to measure the depth of the sea. This echo sounder was installed on fishing boats operating in the North Sea and was used to find reefs that were good fishing spots.

In 1935 Norwegian fisheries scientist Oscar Sund reported that schools of cod were recorded using the echo sounder [1]. Additionally, a Canadian Fisheries Agency research vessel reported that schools of herring were recorded on echo sounders in 1943 [2].

With regard to these reports, the echo sounder could receive echoes from fish schools because the fish schools was composed by large type fishes or swimming densely. Conventional echo sounders were designed with low sensitivity for the purpose of detecting strong echoes from the seabed, and it was difficult to reliably capture the weak echoes from ordinary schools of fish.

Comparison with other companies

After the end of the war, an article on Bendix's fish finder was reported in Reader's Digest in 1949. From the content of the article, it can be inferred that Bendix sold the conventional echo sounders used during the war as fish finders after the war. There is no mention of measures taken by Furuno Electric, such as increasing sensitivity of amplifier or implementing noise countermeasures [3][6].

Supporting texts and citations to establish the dates, location, and importance of the achievement: Minimum of five (5), but as many as needed to support the milestone, such as patents, contemporary newspaper articles, journal articles, or chapters in scholarly books. 'Scholarly' is defined as peer-reviewed, with references, and published. You must supply the texts or excerpts themselves, not just the references. At least one of the references must be from a scholarly book or journal article. All supporting materials must be in English, or accompanied by an English translation.

[1] O. Sund, “Echo sounding in fishery research”, Letter to the Editor, Nature, p. 953, June 1935.

[2] A. L. Tester, “Use of the echo sounder to locate herring in British Columbia Waters”, Bull. Fisheries Research Board of Canada, no. LXIII, pp. 3-21, 1943.

[3] D. Eddy, “Electronic fish-finder”, Reader’s Digest, pp. 105-110, Sep. 1949.

[4] J. Saneyoshi, “Ultrasonic echo sounders and fish finders”, J. IEICE., vol. 34, no. 11, pp. 636-641, Nov. 1951 (in Japanese).


Section 3.5 of this paper describes the early popularization of fish finders. Although there is no direct mention of Furuno Electric's name, the passage that says, “The first to be effective in fishing operations were sardine net fishing boats near the Goto Islands in Nagasaki Prefecture” is an achievement by Furuno Electric. Initially, Furuno Electric had a cooperative relationship with Kaijo Electric, but Furuno Electric succeeded in developing fish finders independently from Kaijo Electric.

[5] K. Kikuchi, “History and prospects of applied supersonic waves”, ibid., vol. 52, no. 9, pp. 1076-1086, Sep. 1969 (in Japanese).


The second page of this paper states that around 1947 to 1948, it was discovered in Japan that echoes from schools of fish could be received by increasing the sensitivity of an echo sounder by 20 dB.

[6] M. Hirano, “Memoirs-The drawn of fish-finder”, J. Acoustical Society of Japan, vol. 42, no. 11, pp. 877-883, Nov. 1986 (in Japanese).


Because the transducer of Mr. Hirano's fish finder was mounted on the side of fishing boat, it is difficult to increase its sensitivity due to noise, and it is assumed that it was only able to detect schools of fish in shallow waters.

[7] J. Fujiwara, “Advance of echo sounder technology from the genesis to today”, ibid., vol. 43, no. 9, pp. 706-707, Sep. 1987 (in Japanese).


The development of a fish finder by Furuno Electric is described. In this paper, Junichi Fujiwara, vice president of Furuno Electric, writes about the early spread of fish finders. Fish finders were first installed in April 1947, and although success in fishing using fish finders was achieved in May 1948, they were not widely used at this stage due to opposition from fishermen. It is stated that the fish finder installed on the fishing boat Masutomi Maru in 1949 was a great success, and that fish finders rapidly became popular.

[8] Y. Nishimori, “Development of the fish finder”, Comm. Rpt. HEE-14-013, IEE Japan, pp. 1-4, Nov. 2014 (in Japanese).


The world’s first practical fish finder was commercialized by Kiyotaka Furuno and Kiyokata Furuno in 1948. The story of their development of the fish finder is described in this paper. This paper describes how a fish finder was realized by improving the sensitivity of the echo sounder and reducing noise. In particular, it describes how a transducer was installed on the bottom of a fishing boat to reduce noise caused by bubble.

[9] Y. Nishimori, “Technological subjects and solution strategies for practical use of fishfinders”, private communication. Dec. 2020 (in Japanese).



In this paper, the difference in sensitivity between fish finders and echo sounders is quantitatively analyzed. It also quantitatively describes the magnitude of noise caused by bubbles generated by the ship's movement, and the fact that the noise was sufficiently reduced by installing a transducer on the bottom of the ship.

[10] Article of Nagasaki News Paper, “Goto's sardine fishing enters the age of electric exploration. Catch that surpasses all others. Efforts that turned intuition into a science”, January 9, 1950 (in Japanese)


This newspaper article reports that a fishing boat named Masutomi Maru, equipped with Furuno Electric's fish finder, had an amazing catch in the fall of 1949.

Supporting materials (supported formats: GIF, JPEG, PNG, PDF, DOC): All supporting materials must be in English, or if not in English, accompanied by an English translation. You must supply the texts or excerpts themselves, not just the references. For documents that are copyright-encumbered, or which you do not have rights to post, email the documents themselves to Please see the Milestone Program Guidelines for more information.

Please email a jpeg or PDF a letter in English, or with English translation, from the site owner(s) giving permission to place IEEE milestone plaque on the property, and a letter (or forwarded email) from the appropriate Section Chair supporting the Milestone application to with the subject line "Attention: Milestone Administrator." Note that there are multiple texts of the letter depending on whether an IEEE organizational unit other than the section will be paying for the plaque(s).

Please recommend reviewers by emailing their names and email addresses to Please include the docket number and brief title of your proposal in the subject line of all emails.