Help me start my 2x 1100HP engines!

I know a guy in the UK that would be able to take a look and give you advice as to how to proceed.

Thanks, so where do we find information on "it's a big boat 27mtrs"
Just sayin

You're right, we don't really need any information to solve your problems.

I there a specific MAN tool? I wasn't aware of that.
A socket wrench with a 32mm hex socket is all it takes.
A ratcheting wrench is almost a must though, because the rotation is a bit restricted by other engine bits around the flywheel.
But with a ratchet, rotating the engine manually is a piece of cake.

Just for OP reference, my wrench can be extended up to 600mm, and it still requires a bit of effort to turn the engine, but not too much - I'm pretty sure that even my wife could handle it!
Not that I ever asked, 'cause I fear the reaction!

PS for the OP: if by chance you've got the flywheel completely exposed, don't look for the cover that CR mentioned.
It's a large metal protection covering all the flywheel+belts+pulleys, which should never be removed, but I've seen plenty of old MAN engines left without it by folks who privilege practicality over safety.
Also because with that cover on it's pretty hard to evaluate the belts conditions.

How about checking the starting batteries first? Have you checked voltage to see if the batteries even have anything in them? I’m guessing they’ve been sitting for years too based on first post?

Out of idle curiosity, since you mentioned that the boat is in England, I just googled around a bit.
Is she possibly the Vitech in Brighton?
I'm asking because the broker ad says that engines conditions are going to be checked, "beginning with turning them by battery to check for free movement".
Now, if that's the boat, in your boots I would urge them to NOT try cranking the engines before having checked manually that they rotate freely by 720 degrees, for the very good reasons already mentioned by Capt Ralph.

Doh!
You did say flywheel, and I also mentioned it in my previous post, but yes, it's actually the front of the engine that I had in mind, and I was referring to the belt pulley instead (including when I mentioned "other engine bits around the flywheel").
Sorry for the misunderstanding.

You made me curious though, because what I explained about manual engine rotation is something I learned from a MAN engineer.
So, I just had a look at the spare parts nomenclature, and as you can see even MAN describe the part I was referring to as "engine turning handle"...

Funny you should mention it.
I thought the same, also because it's rare to see that type of cockpit extension, on this side of the Pond.
Makes me wonder if the boat was originally built like that or lengthened afterwards.
If the latter, I wouldn't trust her for much more than hull speed, because even if not visible in any of the photos, it's very unlikely that the shafts/struts/props were repositioned accordingly.
Besides, I must say that I've only seen a couple of boats built by Kha Shing (as I think this is), and neither impressed me, to be honest.
Still, could be a very comfortable floating residence for someone, I guess.

Yup, for a timing job I'm sure the tool you mentioned allows a much better accuracy.
Also, I agree that while a bar at the front would be easier and faster for rotating the engine twice, that very much depends on engine placement and restrictions around it.
But if the boat is the one we are assuming it is, based on the ad photos the front of the engines is easily accessible.
And unsurprisingly, someone already removed the belts cover that I previously mentioned!

I wouldn't even attempt to turn the motor over with the battery or by hand without pulling the injectors first and lubricating the cylinders with some diesel or etc and leaving it in there overnight, and then trying to bar the motor over by hand.