Drogueless

It appears that some buoys, in the latter part of their drift, may have been drogueless based on the results of certain buoys.

Source: wiktionary

Attempts to correct the movement of drifters (of the same design as those discussed here) for windage have not been successful, either overestimating the downward movement of drogueless drifters (Kirwan et al. 1978), or underestimating the downwind movement of drifters with small drogues (McNally and White 1985).

Source: wiktionary

Although a drogueless buoy is affected by wind, some information on mean circulation can be obtained, especially since the drift was during the summer, when the winds are not strong

Source: wiktionary