Jim,
 
The long 11 and 13 bits are used to bore for 3/4 and 7/8 "drifts" in a shipyard.
They are the metallic equivalent of wooden treenails (pronounced "trunnels")
 
Drifts are metal rods used to edge-join major timbers of a wooden ship, such as
when a keel must be built up of many smaller timbers.  A pilot hole is bored and
then the steel drift is sledgehammered in. The drift can be either bronze (old
ships), wrought iron, or steel.
 
I'd be willing to bet that Ed Minch knows all about this.
 
When you see a decaying wooden shipwreck either underwater or on land, the
drifts are often sticking up like spikes, a danger to the unwary.
 
John Ruth 
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