A deadeye is a wooden disc or oval with two or more holes piecing its face and a grooved outer edge.  These would be encircled with a rope strop which would attach to the chain-plates. A rope (lanyard) would then run through the holes in the deadeye to a corresponding deadeye stropped to the shrouds creating purchase and allowing them to be adjusted forming part of the standing rigging.

SCW648 is much smaller than the other deadeyes in the assemblage and was found just forward of the bowcastle, it is possible that this one have been used on the smaller shrouds or stays of the bowsprit or from the topmasts. Alternatively the deadeye could have been from the rigging of a smaller ships boat.