(1)Whenever by the fault of two or more mechanically propelled inland vessels, damage or loss is caused to one or more of them or to the cargo of one or more of them or to any property on board one or more of them, the liability to make good the damage or loss shall be in proportion to the degree in which each of such vessel was at fault: Provided that-(a)if, having regard to all the circumstances of the case, it is not possible to establish different degrees of fault, the liability shall be apportioned equally;(b)nothing in this section shall operate so as to render any vessel liable for any loss or damage to which such vessel has not contributed;(c)nothing in this section shall affect the liability of any person under any contract, or shall be construed as imposing any liability upon any person from which he is exempted by any contract or by the provisions of any law for the time being in force, or as affecting the right of any person to limit his liability in the manner provided by such law.
