to follow on from my mate, Seaspray, the importance of the bilge keels on a model is basically for cosmetic reasons. This is because they are that small, I do not think they would have the true effect to dampen the roll of the ship.
If it was me, I would put them on, because it doesn't really look authentic enough, especially if it's a cargo ship/warship. They are easy enough to make and fit, and, there are several ways of achieving this.
I have included a couple of photographs of how I fitted plasticard bilge keels to a model I made - where I used brass pins to locate the bilge keels to the hull and Araldited the brass pins on the inside of the hull.
Just going back to the photograph you have put on here - what springs to mind - is - when they put a ship in dry dock, especially of that tonnage, they normally put side supports alongside of the ship as well as wooden blocks supporting the hull bottom. It is strange to see the vessel beached and high and dry out of the water like that. I must be honest I have never seen many vessels like that unless they are ready to be scrapped.
John