'To underrun a tackle' definitions:

Definition of 'To underrun a tackle'

From: GCIDE

Underrun \Un`der*run"\, v. t. To run or pass under; especially (Naut.), to pass along and under, as a cable, for the purpose of taking it in, or of examining it. [1913 Webster]
Note: The cable passes over the bows and stern of the boat used, while the men haul the boat along by pulling upon the cable. --Totten. [1913 Webster]
To underrun a hose (Naut.), to lift it up at one end, then walk along shifting one hand after another so that the water will run out.
To underrun a tackle (Naut.), to separate its parts and put them in order. [1913 Webster]