I installed a Yanmar 27hp diesel on my boat and had 13 years of use from it before selling the boat. Great engine
, and reasonably frugal. Designed really for use on a RIB
as the prop was too small (diameter) and span too fast for efficient use on a bigger boat.
There are some small diesel outboards available in China
, but they look very scrapyard in style.
Ruggerini made about a 15hp engine
for a while, but havent heard of it for a long time, and have never seen one.
Yanmar also made a 36hp version of their outboard, and a number of these were uprated with bigger fuel
pumps to achieve 45 hp. On tests with loaded ribs, twin 45 diesels were the equivalent of twin 75 petrol, and weighed less! If the boat was very light, the petrol were better, and the equivalence then was for twin 55 petrol.