There might be more to the story. Back when Yanmar sold in the US, it was already producing many of the world's large ship engines, but instead of being a corporation it was owned by one guy! Back then some of my friends were local dealers and recall a slick Yanmar in-house mag showing some of the oddball things that Yanmar was making just because the boss/owner wanted to do it. He treated the company like it was his private workshop - which of course it was....sort of like Honda Motors when Mr. Honda decided he wanted to go GP racing.
Apparently the owner of Yanmar International was a nut for futuristic agriculture stuff including fish and sea food farming done both in tanks and in the open ocean. That's why Yanmar started making things like combo sonar/radar and robot fish harvesters. Back on land, his ag hobby also explains why a company mostly dedicated to making two-story sized diesel engines for big ships came to start making little 4WD tractors....as well as why they were made too well and sold too expensively.
For a while Yanmar also made a number of fancy turf maintenance machines and grass cutting equipment. Turf farming just happened to combine the owner's passion for growing things with another hobby - that of collecting golf courses.
Anyway, that was the story at the time; I don't know the guy myself...
rScotty