A Diesel inboard engine is an option on Craft of 7 m and above.
The Yanmar 150 Hp motor is ideally suited to a craft that needs substantial range and where the cost of the craft is an important issue.
Diesel craft are not for all users even the amazing value 150 hp Yanmar when fitted to a Rib with all the necessary housing, bilge pumps, fuel filters, steering, twin batteries and so on all adds up to make a costly craft compared to an equivalent Outboard Package. Diesels also require that the service schedules be adherred to strictly where as with an outboard you can "get away with" not sticking to the service schedule. THIS IS NOT THE CASE WITH A DIESEL !
Unlike outboards they will also not tolerate prolonged high RPM useage so they must be used within a sensible operating RPM range.
Given those limitations if a diesel is what you need then the XS range offer excellent build quality and superb value.
When specifying a craft you need to pay particular attention to the weight of the engine, many of the larger (240 Hp +) 4-5-6 cylinder engines are simply too heavy for a 7 m craft.
Diesel Ribs fall in to classes really, 7 m craft with lightweight motors like the Yanmar etc and then 8 m + craft with more "standard" 250 hp + diesel engines from Yanmar.