So with Jacobsen's dream of driving motorcycles on water and with the Bombardier dream of driving Ski-doos on water, the men joined forces to create something great. The development of the Seadoo PWC had just begun. Jacobsen had used a jet pump to drive his stand-up machine rather than an outboard motor. Once Bombardier sent sent him an 18-hp Rotax engine, Jacobsen started to design a sit-down version of his machine.
The first engines were air cooled instead of water cooled and Jacobsen had trouble designing a hull that would allow in the needed air. Eventually, in 1968 Bombardier bought the right's to Jacobsen's first model. Bombardier revised the design slightly by rounding out the hood and adding yellow and black paint job made famous by Ski-doos.
The next year in 1969, Bombardier updated the original engine. The new engine used liquid-cooling rather than air cooling and that solved a lot of problems. Certain elements of Seadoos that never changed were the bench seats and the steel handlebars. Both of these design elements were taken directly from the Ski-Doo snowmobile designs.
Despite their passion for the Seadoo they couldn't over come certain problems with the engines and corrosion. Jacobsen had a number of great ideas that involved some rubber components and waterproofing but Bombardier failed to incorporate much of those ideas. After 1969 Bombardier gave up on the dream of a Seadoo. They didn't manage put another Seadoo on the market until 1988.
Jacobsen repurchased his patent from Bombardier in 1971 and eventually sold the designs to Kawasaki. Jacobsen's deal with Kawasaki evolved into the creation of the Jet Ski.