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Historical Materials: Maritime & Other Industries & Facilities
Cob / Crib Wharf
The terms "cob wharf" and "crib wharf" refer to a common form of wharf construction dating from pre-colonial times in Europe to the early nineteenth century in America. Both utilize a rectangular frame of timber called a "crib," which forms the foundation of the timber-and-fill structure built over it.The Hamersly Naval Encyclopaedia defines a crib as "a structure of logs filled with stones, etc., and used as a dam, pier, ice-breaker, etc." A cob is defined as "a breakwater or dock made of piles and timber, and filled in with rocks. The vagueness of these definitions probably explains the interchange of these terms in contemporary descriptions. (1)
In Lane's paintings of Gloucester Harbor, we see what could be both examples of these wharf types on the point of land inat far left. The wharf built up of layers of cribs (like a log cabin) fits the definition of a crib wharf, while the wharf beyond it with vertical pilings enclosing exposed stone would be a cob wharf. Going by this observation, other examples of cob wharves can be found in the depictions of Harbor Cove from the 1840s in , , and .
Going by the Hamersly definition of cob wharf, coupled with recent archeological studies of Boston's old waterfront, this constuction was used for both finger piers and bulkhead piers in Gloucester Harbor. Thus, the bukhead piers adjoining and linking the wharves on Fort Point were cob wharves, their stone fill appearing no different from that of the finger piers. (2)
The stone fill used in these wharves was rubble stone: beach stones, field stones, and boulders broken into irregular shapes. Shaped stone blocks of quarried granite do not appear in Lane's depictions of wharves until George H. Rogers began construction of his wharf on Fort Point as noted inand . The building of this wharf marks a clean break with older wharf construction in Gloucester's Harbor Cove.
– Erik Ronnberg
1. A Naval Encyclopaedia (Philadelphia: L. R. Hamersly & Co., 1884. Reprint: Detroit: Gale Research Co., 1971), 146,182.
2. Nancy S. Seasholes, Breaking Ground: A History of Landmaking in Boston (Cambridge, MA: The MIT Press, 2003), 13–19.
Wood, metal, and paint
20 1/4 x 10 1/4 x 10 1/2 in., scale: 1/2" = 1'
Made for the Columbian Exposition, Chicago, 1892–93
Cape Ann Museum, from Gloucester Chamber of Commerce
The wharf is built up of "cribs", square (sometimes rectangular) frames of logs, resembling a log cabin, but with spaces between crib layers that allow water to flow freely through the structure.Beams are laid over the top crib, on which the "deck" of the wharf is built. Vertical pilings (or "spiles" as locally known) are driven at intervals to serve as fenders where vessels are tied up.
– Erik Ronnberg