c.1386, "wrecked ship," probably from M.Du.
wrak "wreck," cognate with O.E.
wræc "misery, punishment," and
wrecan "to punish, drive out" (see
wreak). The meaning "damage, disaster, destruction" (in
wrack and ruin) is from c.1408, from the O.E. word. Sense of "seaweed, etc., cast up on shore" is recorded from 1513. The verb meaning "to ruin or wreck" (originally of ships) is recorded from 1562, from earlier intrans. sense "to be shipwrecked" (1470). Often confused in this sense since 16c. with
rack (1) in the verb sense of "to torture on the rack;" to
wrack one's brains is thus erroneous.
[rak] 
