Originally Posted by SixtyNorth
All good stuff, thanks, made some interesting reading. Did they not see any advantage of having twin engines on an inshore (SIB) lifeboat or had the 2 stroke outboards proved to be reliable enough?
Like anything it is a trade off. I'm guessing after the D class proved such a success someone saw the benefits of a 'bigger D class' , hence the C class. I suspect the main reason the C class ended with twin 40s rather than a 50 or 60 was precisely to give the redundancy in the event of an engine failure.
Trouble is with the extra size and weight and physical effort required the D class could outperform it in the surf, then the Atlantic 21 came along and could outperform it everywhere else, so it ended in an evolutionary dead end.
There are a couple of lifeboat stations now with Arancias (originally New Zealand built SIBs for beach lifeguard use, now built under licence by the RNLI) and RWCs (jetskis) because coast reviews identified that there were times that even a D class was too big / heavy.
You couldn't fit twin OBs to a D class without compromising its operational capabilities, so all you can do is make the kit as reliable as possible, plan for every eventuality, and train the hell out of the crew so they can handle it if / when it happens.