DCHP-1 Online
boom chain 
a chain linking two boomsticks or boom timbers.
See also: boomstick boom timber
- 1883 The first business of the drive is to collect all these scattered timbers, and "boom" them into the main channel of the river, that is, confine them there by long half-square logs called "boom timber," fastened at the ends by "boom chains."
- 1956 . . . a small pile of boom chains abandoned on the shore for some reason [was] now a rusty lump.
- 1883 The first business of the drive is to collect all these scattered timbers, and "boom" them into the main channel of the river, that is, confine them there by long half-square logs called "boom timber," fastened at the ends by "boom chains."