While the fact that a claimant’s work places him on several different vessels does not preclude seaman status, it is relevant in making that determination. As we stated in Longmire, “[t]he issue of an injured worker’s status as a seaman should be addressed with reference to the nature and location of his occupation taken as a whole.” Longmire, 610 F.2d at 1347. Consequently, the character and extent of a worker’s service aboard vessels, whether it be one or several, affects the resolution of seaman status. We have repeatedly emphasized that “the relationship creating seaman status must be substantial in point of time and work, not merely sporadic.” Dove v. Belcher Oil Co., 686 F.2d 329, 333 (5th Cir.1982). See, e.g., Barrios v. Engine & Gas Compressor Services, Inc., 669 F.2d at 353; Roberts, 648 F.2d at 261; Guidry v. Continental Oil Co., 640 F.2d 523, 529 (5th Cir.), cert. denied, 454 U.S. 818, 102 S.Ct. 96, 70 L.Ed.2d 87 (1981); Rotolo v. Halliburton Co., 317 F.2d 9, 13 (5th Cir.), cert. denied, 375 U.S. 852, 84 S.Ct. 111, 11 L.Ed.2d 79 (1963); Braniff, 280 F.2d at 528. As the number of vessels increases or the period of service decreases, the claimant’s relationship with the vessels tends to become more tenuous and transitory. See Aparicio v. Swan Lake, 643 F.2d 1109 (5th Cir.1981); Fazio v. Lykes Bros. Steamship Co., 567 F.2d 301 (5th Cir. 1981). Individually, these factors are not determinative, e.g., Brown v. ITT Rayonier, Inc., 497 F.2d 234, 237-38 (5th Cir.1974) (temporary relationship insufficient to deny status); Braniff, 280 F.2d at 528 (status allowed although assigned to several vessels); however, to the extent that they reveal the nature and location of a claimant’s work, they should be considered when applying the Robison criteria. Accordingly, we turn to the facts to decide whether reasonable persons could find that plaintiffs qualified as seamen under the Robison test.
The two criteria of Robison are conjunctive. E.g,, Davis v. Hill Engineering, Inc., 549 F.2d 314, 328 (5th Cir.1977). Plaintiffs satisfy the second part because the performance of the anchorhandlers’ duties clearly contributed to the accomplishment of the vessel’s mission, the relocation of the drilling barge. Thus, we turn to the first criterion, which concerns the issue of the injured workers’ connection with a vessel, and note that “it offers alternative grounds for meeting the standard.” Id. at 326. Although this aspect of the test addresses the threshold inquiry of whether the claimant has had sufficient contact with waterborne or vessel-related activities, Landry, 595 F.2d at 1072, we have sometimes emphasized the permanency aspect to the apparent exclusion of the substantial work prong of the standard. See, e.g., Guidry v. Continental Oil Co., 640 F.2d at 529 & n. 19.11 Nevertheless, the worker may satisfy the requisite vessel relationship by demonstrating the performance of a substantial part of his work aboard a vessel, e.g., Landry, 595 F.2d 1070, or a permanent assignment to a vessel. E.g., Ardoin, 641 F.2d-277.
For a claimant to satisfy the substantial work prong of Robison, “it must be shown that he performed a significant part of his work aboard the vessel with at least some degree of regularity and continuity.”' Barrios v. Engine & Gas Compressor Services, Inc., 669 F.2d at 353; Holland, 539 F.2d at 484; Keener, 486 F.2d at 732. The undisputed facts reveal that the anchor-handling crew worked on twenty-five vessels and that approximately ninety per cent of the work was performed aboard the vessels. Bertrand, 517 F.Supp. at 344 (undisputed fact XI). Compare Abshire, 668 F.2d at 835 (90-95% work on 21 vessels — seaman) and Landry, 595 F.2d at 1073 (70%
11
Although the analysis in some cases focuses upon the claimant’s failure to meet a particular prong, usually the permanency prong, the facts of the cases reveal that neither alternative was satisfied. For example, the plaintiff in Guidry, a casing pusher on a drilling barge, admitted in deposition that he had no permanent assignment to any particular drilling vessel or group of vessels. While we focused on the lack of a permanent attachment, the nature of his work placed him on vessels for only half of his assignments and required him to work only about twenty per cent of his time on those vessels. Consequently, this minimal vessel-related work evidences the failure of the substantial work alternative.