There's a world of difference between a gas engine and a diesel.

I have no doubt that larger diesels can be hand started but, as you said,
set up has a lot to do with it. Working in the confines of the typical
small boat cabin without being able to use your body effeciently and the
crank at an angle is going to make a big difference.

The real world, reported experience, here and other places, is that with the
typical sailboat set up, 12 -15 is a bear and 20 can be done but not
reliably. I talked to a fellow yesterday who got his 3 cylinder going once
but was never able to duplicate the feat.

I'm sure there are exceptions. With the boat and installation designed from
the beginning to make hand starting a priority, starting a larger engine
would be possible. Problem is, it is generally an afterthought if it is
given any thought at all.

--
Roger Long