Help me start my 2x 1100HP engines!

Well, What engines are they?
Were they pickled before storage?
Those fresh batteries?
Boat stored in the water? Exhaust was open or closed for storage?

Turning by hand?? With a big bar?

Are you expecting intelligent answers if you don’t bother telling us what model engines, what kind of boat etc. impossible to answer.

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

Your not going to turn a cold V12 by hand.
Your not going to do it with old batteries.

You did not mention if the engines were pickled before storage?
Or exhaust ports sealed?
This leads to my first thoughts;
Stuck valves in the heads.
Rust on the valves and valve seats.
Rust on the cylinder liners.

There is a service opening on the flywheel cover that accepts a MAN engine turning tool.
A 1/2" (12mm) bar or large ratchet can turn the engine over from here.
Don't poke a pry-bar in there and try, damage to the flywheel teeth will result.
Using this tool offers a nice ratio turning the flywheel. You can move the engine over but can feel if something is wrong, like a stuck valve or piston.
Then you go pulling rocker covers and heads.

If you can get more than 2 turns with out any crunches, prime some fresh fuel filters (w fresh fuel), load up some fresh batteries and start them up.

The mechanical MAN V12s are popular over here. Not a lot of them but those that have them are very happy.
Be ready to change the engine oil promptly.
Send coolant, fuel, and oil samples to your lab promptly.

Don't forget to check out your clutches and raw water pumps.

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.

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.

I'm not referring the front of the engine, the engine/clutch adapter that I call the bell-housing that covers the flywheel with starter ring.
A tool attaches to a square hole. With gear reduction, takes little effort. Just slow.

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"...

On some I have worked on, a cover and tight access blocks the front of the engines. The frames and other junk gets in the way of swinging a tall bar.
Oh, it was a MAN engineer that turned me to this also. Further, the more reliable timing marks are back here.
If you can reach yours, great. The reduction on this tool will take a while to turn the crank twice.
But you can still feel the restriction. Been there, yep, dropped valve. Saved that piston.
I luv single heads.

Now on my V-12 Detroits, That is where to turn the crank from. Lots of room.
A pipe on the end of a breaker bar and I can move the crank with lil effort and precision.

Well, Sale pending on that boat.
I kind of liked that super long look.

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 had to register if I wanted to see more than the first picture.
So,,, I did not see any more pictures than the first one.