Hi

"James" wrote in message ...
But a lot depends on why she is sunk.
If she has large hole (or holes) the problems are different to if she sunk
slowly due to heavy rains over a long period of neglect.
If the hull is sound and you beach her, you will have to pump her out as the
tide goes down... or the water inside will very possably damage her.
If she is somewhere non tidal.. thats a different set of prodlems
More data is required!

The safest way its to get your hands on one or two barges, the concept
is that you get wires around the hull and tigh these as tight you can
onto each barge each side the sunken vessel, then you flood the barges
as much you can tigh the wires again and bail out the water of the
barges.
You say the weight is round 40 tonn ,but I guess this is lower
submerged ,still as what James say it is about the final step ------
to be sure that when you can't lift more by bailing out water from the
barges, that the deck is above water, as if not you must plan to have
the sunken hul free from the sea bed so you can move it to more
shallow water and redo the process untill enough of the deck is above
water. You se even it is 40 tonn you don't need more than 40 cubic
meters to lift that and you soon reach this volume . Then where most
make the mistake, is not preparing for the final lift, as quite often
just a feet or so is what is needed ----- that case be prepared to
stop the leaks ,build a temp. wall and have plenty of pumps.