noun
or sir·mark ˈsərˌmärk
Etymology: surmark from sur- + mark; sirmark probably alteration (influenced by sir ) (I) of surmark
1. : a mark made on the molds of a ship when building to show where the frames should be beveled
2. : a cleat temporarily placed on the side of a ship on the ways or in a ship dock to support the ribband against which the shores rest