opinion: PER CURIAM.
  We assume arguendo that there was a covenant to return the float in good condition wear and tear excepted. We assume, likewise for argument only, that this imposed an unconditional liability on the charterer, unless the float was destroyed without its'fault! Nevertheless we do not understand the libelant even to argue that the owner does not on a demise warrant a float’s seaworthiness; that is, her fitness for the traffic for which she is let. That is, of course, the rule. . .
  So viewed, the question really comes to whether the way in which the float was unloaded was negligent. The evidence is that the railroads differ about this. The New Haven and the New' York Central adopt one method, and the Delaware, Lackawanna & Western and Long Island adopt that used here. The practice of the other roads does not very clearly appear, but it is apparent that there is a difference between persons expert in the calling as to what is the safest way. We are in no position to say which is right, or indeed whether there is any right or wrong way at all. No doubt there are cases in which we interpose our own views, when the practices of experts differ. This is not one; we cannot say whether the torque of the New Haven practice is worse than the strain of the Long Island. The charter exposed the float to current practices of the port unless plainly bad, and the libelant was charged with notice of what these were.
  The conclusion from her failure that she was unfit is fortified by her structural weakness. Instead of six fore and aft trusses, she had four. Certainly it was permissible for the District Judge to find that she had been badly designed, even from the outset. The fact that she had not failed before is not conclusive. Her sister, No. 47, had failed under a similar strain, and half the series had been made over to hold only two strings of cars. Besides, after 16 years, nobody can say what weaknesses she had developed. The loads had all the while been slowly increasing, and for these she had- not originally been designed.
  We can find nothing in the record which justifies a reversal.
  Decree affirmed.