Generally the boat will have to be on land as it needs to be stable. Long fork on a forkie truck, lift through the patio door. Some engines are too large for this, and you cut a hole in the fly floor and lift through there.
Pretty much as rafiki said....
Usually remove patio doors and occasionally requires a cut, then fork lift or tele handler in through the doors.
Can be really destructive to be honest. The newer the boat, usually the better. The engines tend to be more compact and easier to remove.
Older prIncess/fairline and similar from late 80's and early 90's with the big tamd61 and similar would be difficult. They tend to be put in first (at build), then the rest of the boat built round about them.
If possible, best to strip the engine of all that's possible...ancillaries, heads(s) etc and down to the bare block.
Not a nice thought..but good luck.
only looking at worst nightmare ,but thinking about it ,she has been re engined so may be just patio door which i have had out before ,but i am positive
On our Princess 435, for the port engine we had the patio doors and frame taken out, the steps cut down and the cockpit dodgers and cover frame removed, then a forklift tine was used, all on the water. The engine had been stripped as far as possible and there was still only a couple of cm clearance. I dread to think what would happen if the starboard engine needed to come out - the cabin would have to be deconstructed.
Well I am just feeling the way as we are still working on the engine Iam going boat tomorrow so will measure length from stern maybe extended forks on for more get be ok ,
I had M225Ti in a 28ft open boat, I hooked them out afloat once, when I lifted the first one out the boat took on a heel of about 20 degrees, it doesn't make the job easier. Do it ashore.
I'd pull it out, clean it, pressure test the manifolds and coolers, hone bores, clean up any rust etc, pop it back together, dyno test it, paint it, pop it back in.
I found Perkins spares to be very well priced.
If you run into real big trouble I do know of a spare M225Ti.
here in this link you can see how we took out one engine of our boat for rebuild,
(while the boat was in the water)
probally different from more modern full GRP boat's
but just for inspiration: