Primary source · Yamaha · 1970–1987
The 30hp problem that shaped the first hull
Yamaha wanted fifty horsepower for its first sit-down craft and could only get thirty. The double-chine hull almost every runabout still uses is what the engineers did about it. This is Yamaha's own account of the years before the first machine shipped, and it is the part of the story that the model lists leave out.
Not yet reviewed. Every figure below was read from the source named against its section, and nobody has checked this article back against those sources a second time.
The hull shape is an answer to a power shortage
Yamaha's engineers judged that the craft needed about fifty horsepower to be genuinely fun to ride. The base engines available to them were derived from outboards and topped out at thirty. Rather than wait for an engine that did not exist, they went at the problem through the hull: a shallow V with two sets of chines instead of one. The inner chines were set at a width chosen to cut through the water and raise speed at low power. The outer chines added stability when the craft was sitting still, made the turn controllable as the rider's weight moved forward, and sharpened the handling. That geometry outlived the constraint that produced it, which is why it is worth knowing: a hull feature that reads today as a styling decision started as a workaround for a thirty horsepower ceiling.
The first presentation to the US company failed
In September 1984 Yamaha took its prototype, named Power-Ski in house, to its United States company. It weighed sixty five kilograms dry and made twenty five horsepower. The response was that the craft was wrong for the market in a specific way: it should be heavy enough that nobody could lift it by hand, trailered rather than carried, with something around one hundred and thirty kilograms considered acceptable. The craft itself was a mixed build, and Yamaha says so: a twenty five horsepower engine of its own against a fifteen horsepower jet pump bought in from another company. It had run well in trials on Lake Hamana. The failure in America was not subtle. Test riders weighing more than one hundred kilograms and standing over one hundred and eighty centimetres struggled to get onto a board built around Japanese proportions, and the question became commercial before anyone could judge how it performed.
From: Yamaha Motor, WaveRunner 30th Anniversary, Story, Yamaha Motor, History of WaveRunners
Eleven months later the same riders would not get off
The in-house project formally began in February 1985 under the name MMV, for Mini Marine Vehicle, this time with the United States company backing it, and single and tandem models were developed together. At the second presentation in July 1985 the tandem was the one that landed: Yamaha's account is that the test riders would not get off it. The tandem was approved for tentative production at that meeting and the name Wave Runner was chosen at the same point. A second prototype was shown alongside it, the one that became the WaveJammer, sharing the tandem's boat-shaped construction but with fixed steering. The seated tandem was shown publicly at the Chicago Boat, Sports and RV Show in 1986. Yamaha's two accounts of what happened next do not quite line up: its global history gives a Japanese release of the MJ-500T in November 1986 and puts the single-seat MJ-500S at January 1987, while the anniversary microsite dates production starts to October 1986 and February 1987. Release and production start are different events, so both can be true, and neither page says which it means.
From: Yamaha Motor, WaveRunner 30th Anniversary, Story, Yamaha Motor, WaveRunner 30th Anniversary, History, Yamaha Motor, History of WaveRunners
In Japan the law arrived before the product did
The development manager was stationed in Shonan in the early 1970s, then the centre of Japan's marine leisure business, at a time when small craft needed no licence to operate. A limited number of overseas-built craft were imported in 1979. In 1980 Japan issued what the source calls water-bike special standards, creating the legal framework for small-watercraft leisure, after the Ministry of Transport asked the industry to help set the technical standards. Yamaha's account has its own manager sitting on the Japan Marine Industry Association technical committee and running the Shonan safety testing that fed into those standards. Read that with the interest in mind: the manufacturer is describing its own role in writing the rules its product would be sold under.
Where the thirty horsepower ceiling came from
The engine and jet propulsion work was done with Sanshin Industries, the Yamaha group company that developed outboard engines. That partnership is what set the constraint the hull had to solve, because the base engines Sanshin could supply were outboard-derived and capped at thirty horsepower against the fifty Yamaha wanted. The two facts belong together and are usually reported apart: the hull is not an aesthetic lineage, it is the visible result of an engine supply decision made before the first craft shipped.
Every "world's first" here is a qualified first
Yamaha's pages carry five of them: the first sit-down open-stern production PWC and the first tandem in 1986, the first three-passenger in 1990, the first four-passenger in 1999 and the first four-stroke in 2002. Each one is worth repeating only with its qualifier attached, and the reason is on Yamaha's own site. Its concept page acknowledges that small personal watercraft were already being produced in the United States in the 1970s, solo-rider only and difficult to master. So these are firsts inside a category Yamaha defined rather than firsts outright, and the 1968 Sea-Doo sits before all of them. The origins page on this site sets out who actually got there first, and where the accounts disagree.
From: Yamaha Motor, WaveRunner 30th Anniversary, Concept, Yamaha Motor, WaveRunner 30th Anniversary, History
Caveat
This is a manufacturer's account of its own product, published as an anniversary piece. That makes it first-party and therefore strong on dates, names and intent, and it also makes it interested in the answer to who was first and in whose engineering deserves the credit. Nobody here has checked it against a Japanese-language source, a contemporary press report or anything from the companies it competes with.
Every issue cited here
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Other sources cited here
- Yamaha Motor, WaveRunner 30th Anniversary, Story
- Yamaha Motor, History of WaveRunners
- Yamaha Motor, WaveRunner 30th Anniversary, History
- Yamaha Motor, WaveRunner 30th Anniversary, Concept
Full index of the magazine at Yamaha News PWC index, where the scope of what has actually been read is stated: most issues have had their index read and not their body text. Yamaha permits personal use only and prohibits redistribution, so nothing here is rehosted or excerpted. Every citation links to Yamaha's own PDF.
Yamaha · 1970–1987 · 0 issues cited