I'm sure that many engines were changed that way during the Cat's career, and many spanners will have fallen into the water while doing this. You'd also need a vessel to transport the spare engine, move the engines on and off that vessel, and everything would be moving on the water while the whole process is going on. Much easier to do it on land.
Originally Posted by DaveReidUK
And fingers crossed that the problem (something that was preventing the starter turning the crankshaft over) will turn out to be something that doesn't require a full overhaul.
The current suspect is the accessory drive shaft. I don't know enough about R-1830s to know whether that's a big or a small job. I suspect it's a big one though.