surmark

from The Century Dictionary.

• noun In ship-building: One of the stations of the rib-bands and harpings which are marked on the timbers. See rib-band line, under rib-band.
• noun A cleat temporarily placed on the outside of a rib to give a hold to the rib-band by which, through the shores, it is supported on the slipway.

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

• noun (Shipbuilding) A mark made on the molds of a ship, when building, to show where the angles of the timbers are to be placed.

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

• noun shipbuilding A mark made on the moulds of a ship to show where the angles of the timbers are to be placed.