tiller-comb

from The Century Dictionary.

• noun In marine hardware, a quadrant rack or comb having a single row of shallow teeth: designed to be secured to the deck of a boat immediately under the tiller. A short blade called the knife is fastened to the under side of the tiller, and to hold it in any desired position, in sailing or at anchor, the tiller is dropped until the knife falls between two teeth of the comb.