opinion: Mr. Justice Douglas
  delivered the opinion of the Court.
  Petitioner, Crumady, was an employee of a stevedoring company engaged in transferring a cargo of lumber from the ship Joachim Hendrik Fisser of German registry to a pier at Newark, New Jersey. While so engaged, he was injured and brought this admiralty suit by libel in rem against the vessel. The vessel impleaded the stevedoring contractor.
  When the accident happened the stevedores were trying to lift two timbers through a hatch. The manner of the accident was described as follows by the District Court:
  “. . . libellant and his fellow-employees had placed a double-eyed wire rope sling, provided with a sliding hook movable between the eyes thereof, around the two timbers at a location two or three feet from their after ends. The two eyes of the sling were then placed upon the cargo hook of the up-and-down boom runner and a signal given by the stevedore gangway-man to the winchman to 'take up the slack.’ The winchman complied with the signal, and during this operation libellant stood clear upon other timbers forming a part of the cargo, within the open square of the hatch. There was some testimony that when the slack was taken up by the winchman, the two timbers slid toward each other in the sling, the timber which had been under the lower edge of the hatch coaming moving or commencing to move toward the timber which lay within the open hatch square. After the slack had been taken up by the winchman, the same signaller called for the ‘taking of a strain’ •upon the cargo runner. The winchman again responded, the two-part topping-lift broke and the head of the up-and-down boom, with its attached cargo and topping-lift blocks, fell to the top of the cargo within the hatch square.
  “The topping-lift had been rigged in a double purchase and had been supporting the head of the boom. The wire rope constituting the topping-lift extended from a shackle on the topping-lift block at the cross-tree of the mast, through a block at the boom head, back through the mast block, down the mast, through a block welded to the mast table, and thence around a drum of the winch. When the boom fell, libellant was knocked down, either by the boom itself or its appurtenant tackle, and thus sustained numerous serious and permanently disabling orthopedic and neurological injuries.” 142 F. Supp. 389, 391.
  The safe working load of the boom and cargo runner and topping-lift handling the load at the time of the accident was three tons each. This equipment, which was part of the unloading and loading gear of the vessel, was in good condition. The winch, which served the boom, had a “cut off” device or circuit breaker. It was set to shut off the current on the application of a load of about six tons, which was twice the safe working load of the unloading gear. The circuit breaker operated perfectly, cutting off current at the point of stress for which it was set. It had been set to operate at a load slightly more than twice the safe working load of the unloading gear by employees of the ship before the winch was turned over to petitioner’s fellow employees for operation.
  The District Court accordingly found the vessel unsea-worthy and therefore liable to petitioner. It also found that the stevedores moved the head of the boom in an effort to clear the cargo from the sides of the hatch and that this “created a load on the topping-lift greatly in excess of its safe working load.” This act was found to be “the primary cause of the parting of the topping-lift and consequent fall of the boom.” Since the stevedoring company was found to be negligent in bringing “into play the unseaworthy condition of the vessel,” the District Court directed the stevedoring company to indemnify the vessel for the damages to petitioner. 142 F. Supp. 389. The Court of Appeals reversed, holding that the vessel was not unseaworthy and that the sole cause of the injury was the negligence of the stevedores. 249 F. 2d 818. A petition for rehearing was denied en banc, Judge Biggs dissenting. 249 F. 2d 821. The cases are here on petitions for certiorari. 357 U. S. 903.
  I. We held in Seas Shipping Co. v. Sieracki, 328 U. S. 85, 95, that stevedores, though intermediately employed, are, when performing “the ship’s service,” entitled to the same protection against unseaworthiness which members of the crew doing the same work would receive. And see Pope & Talbot v. Hawn, 346 U. S. 406. The work of loading and unloading is historically “the work of the ship’s service.” Seas Shipping Co. v. Sieracki, supra, at 96.
  This protection against unseaworthiness imposes a duty which the owner of the vessel cannot delegate. Seas Shipping Co. v. Sieracki, supra, at 100. Unseaworthiness extends not only to the vessel but to the crew (Boudoin v. Lykes Bros. Steamship Co., 348 U. S. 336) and to appliances that are appurtenant to the ship. Mahnich v. Southern S. S. Co., 321 U. S. 96. And as to appliances the duty of the shipowner does not end with supplying them; he must keep them in order. Id,., at 104; The Osceola, 189 U. S. 158, 175. The shipowner is not relieved of these responsibilities by turning control of the loading or unloading of the ship over to a stevedoring company. It was held in Grillea v. United States, 232 F. 2d 919, that stevedores themselves could render a ship pro tanto unseaworthy and make the vessel owner liable for injuries to one of them. And see Rogers v. United States Lines, 347 U. S. 984; Alaska S. S. Co. v. Petterson, 347 U. S. 396. We need not go so far to sustain the District Court here. For there is ample evidence to support the finding that these stevedores did no more than bring into play the unseaworthy condition of the vessel. The winch — an appurtenance of the vessel — was not inherently defective as was the rope in the Mahnich case. But it was adjusted by those acting for the vessel owner in a way that made it unsafe and dangerous for the work at hand. While the rigging would take only three tons of stress, the cutoff of the winch — its safety device — was.set at twice that limit. This was rigging that went with the vessel and was safe for use within known limits. Yet those limits were disregarded by the vessel owner when the winch was adjusted. The case is no different in principle from loading or unloading cargo with cable or rope lacking the test strength for the weight of the freight to be moved. In that case the cable or rope, in this case the winch, makes the vessel pro tanto unseaworthy. That was the theory of the District Court; it correctly applied the concept of unseaworthiness; and its findings of fact were not clearly erroneous. McAllister v. United States, 348 U. S. 19, 20.
  II. A majority of the Court ruled in Ryan Co. v. Pan-Atlantic Corp., 350 U. S. 124, that where a shipowner and stevedoring company entered into a service agreement, the former was entitled to indemnification for all damages it sustained as a result of the stevedoring company’s breach of its warranty of workmanlike service. And see Weyerhaeuser S. S. Co. v, Nacirema Co., 355 U. S. 563. The facts here are different from those in the Ryan case, in that this vessel had been chartered by its owners to Ovido Compañía Naviera S. A. Panama, which company entered into the service agreement with this stevedoring company. The contract, however, mentioned the name of the vessel on which the work was to be done and contained an agreement on the part of the stevedoring company “to faithfully furnish such stevedoring services.”
  We think this case is governed by the principle announced in the Ryan case. The warranty which a stevedore owes when he goes aboard a vessel to perform services is plainly for the benefit of the vessel whether the vessel’s owners are parties to the contract or not. That is enough to bring the vessel into the zone of modern law that recognizes rights in third-party beneficiaries. Restatement, Law of Contracts, § 133. Moreover, as we said in the Ryan case, “competency and safety of stowage are inescapable elements of the service undertaken.” 350 U. S., at 133. They are part of the stevedore’s “warranty of workmanlike service that is comparable to a manufacturer’s warranty of the soundness of its manufactured product.” Id., at 133-134. See MacPherson v. Buick Motor Co., 217 N. Y. 382, 111 N. E. 1050.
  We conclude that since the negligence of the stevedores, which brought the unseaworthiness of the vessel into play, amounted to a breach of the warranty of workmanlike service, the vessel may recover over.
  The judgment of the Court of Appeals is reversed and the judgment of the District Court is reinstated.
  It is so ordered.
  One expert, Robert A. Simons, testified:
  “I said that it is not safe practice to have a rig that was designed for three tons working load and of the winch with a cut-off set at six tons so that you could apply six tons load to the hoist before the winch would cut off because that would be doubling the load for which the rig was designed for.”
  Another expert, Walter J. Byrne, testified:
  “. . .if you have three-ton gear and a three-ton winch and due to cut-offs in back, you allow, let us say, a hundred per cent overload to be developed, then I think from my point of view as a safety man you are taking away a governor. You are taking away something which is built in for the protection of the gear and personnel.”