dogshore

from The Century Dictionary.

• noun In ship-building, one of the shores or pieces of timber used to prevent a vessel from starting during the removal of the keel-blocks preparatory to launching.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Naut.) One of several shores used to hold a ship firmly and prevent her moving while the blocks are knocked away before launching.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun nautical One of several shores used to prevent a ship from moving while the blocks are knocked away before launching.