Friday, May 27, 2016

The humble ships spike: what’s in a name?

As I tried to make clear in my last blog post, ships fastenings can tell us about the construction of boats and ships in the Chesapeake, but they can also tell us about the life of a vessel.  The lowly ships spike is a great example.  They are often misidentified in the catalogues of archaeological excavations all over the Chesapeake region.  While generally similar to large nails used in terrestrial architecture, both wrought iron ships spikes and ceiling nails have a much wider shoulder just below the rose head. 
As a general rule the use of iron fastenings on ocean going vessels during the 17th and 18th century was not considered best practice.  However, there comes a point in the life of a vessel that the primary fastenings, the treenails, fail to hold even after successive repairs.  Often as a last step wrought iron ships spikes are added to draw the outer planking back down.  In poorly constructed vessels this can be done at the onset of construction.  The wider shoulder on wrought iron ships spikes and ceiling nails had the purpose of compressing the wood in the planking and to draw it taught to the framing (Fig. 1A).  The ships spikes also had the advantage that as the ship hogged, pitched, and twisted as it sailed, the nail head wouldn’t loosen as it had been pre-compressed when applied. 
Fig. 1

Ships ceiling nails, if purpose made, would have had the same wide shoulder as the repair type ships spikes (Fig. 1B).  Often times though, purpose made ceiling nails would not have been available to boatyards.  Both of these fastenings required special nail making tools to fabricate.  It is not an odd occurrence to see normal board nails in the ceiling planking of boats and ships constructed in the Chesapeake during the 17th and 18th century. 

As ships spikes were added at the end of a vessels life cycle, they were often taken out when the ships were broken down and reused as they contained a considerable amount of iron content.  Sometimes lose timbers wash up on our shores from the 17th and 18th century which have “molds” of the ships spikes heads (Fig. 2). 
Fig. 2

2 comments:

  1. Would love to see a photo of one.

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  2. Hopefully the Alexandria Ship will provide publishable data.

    ReplyDelete