The field vane test is usually used to measure the strength of clays, but it may also be applied to measurements in silty soils. Because of the relatively high permeability of silts, drainage of the soil surrounding the vane can take place even during a fairly rapid test.A method is proposed that enables the preselection of a test duration such that the strength measured is that of the fully drained soil. The procedure has been developed by both empirical and theoretical means.