Hi Alasdair
I recall seeing quite a few 'headless' copper alloy fastenings in the
collection from the wreck of the PS Clonmel(1841). The majority of them are at the Heritage Victoria Conservation
Lab.
Many of the smaller fastenings from the Clonmel are likely to be sheathing tacks. They were all located in a scour hole on
the site; some look used and others look like they were probably carried
for repairs. The fastenings are in a variety of conditions ie. bent, with
heads, without heads, broken part way along the shaft etc.
These may be useful for comparative purposes with the Port Arthur
assemblage. Given that one of the primary occupations at Port Arthur was
boat building I would presume that this was the function of most of these
fastenings.
Perhaps an interpretation may be that the heads have been snipped off
while recovering copper sheathing (in a ship building/repair yard)  in
order to replace hull timbers on a ship, and the removed timbers have been
taken to the metal workshop for reuse? The timber may then have been burnt
or have rotted in the soil, leaving just the copper alloy.
I guess it may also be possible that the metallographic structure of the
copper alloy caused breakage at the top of the shaft just near the head
(ie perhaps through galvanic corrosion with the copper alloy of sheathing,
maybe even combined with the force of hammering the nail through the
sheathing and into the timber initially). Just a few ideas from the
maritime unit (big thanks to Peter Harvey for his interpretive
contributions!). Good luck!

Cheers
Cass

_________________________________
Cassandra Philippou
Maritime Heritage Unit
Heritage Victoria
Level 17, Nauru House
80 Collins Street
Melbourne
Victoria 3000

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