Capn Jack wrote:However, I don't think sterndrives are derivatives of outboards, although I'll always listen to reason and absolutely stand corrected. I remember my Grandfather and my Dad talking about engines and drives and I don't remember there being a link. As I understand it, outboards were originally designed for craft which were powered by oars, the sterndrive evolved through a necessity to reduce space within cruisers, that is, to put the engines in the stern to give more space within the boat itself.
Outboard engines historically, have been built for fast craft revving to 5,800rpm, whereas sterndrives are more.....how can I put it, well they have more grunt/muscle pushing tonnage at speed but not at the speed of outboards.
I found this article, which doesn't really say why but a development of the need to overcome the defficiencies of outboards and shaft drive inboards.