I'm pretty sure its metric as my uncle the colonel used it when sailing 16ft skiffs i believe a smidgen was the imperial unit 
Definitely imperial. The metric term would replace that term with the gender neutral "bee's genitalia" to fit with current thinking. Or about this much:
Definately imperial!
In a former life I was a fitter & turner; in the trade, a bee's dick was 'half a thou' (ie. 0.0005") however the use of the term was expanded to include any amount that was 'less than a thou'*.
Perhaps Frant was a boilermaker? (boilermakers having, over time, adopted their own approach to measurement & tolerances).
Any serious discussion on this matter would not be complete without mentioning another imperial unit, the "c$$t hair".
This unit is a distance equal to 'two thou' (ie. 0.002") (plus or minus a bee's dick).
Those of you with access to both a micrometer and an actual "c$$t hair" will be able to verify this.
Note: both the "bee's dick" and "c$$t hair" are singular units, and as such are only used by themselves and never in the plural sense.
You would NEVER refer two "two bee's dicks", or "three c**t hairs"; that would just be silly!
I trust that this helps clear things up.
*Reference: Page 2435 MAchinery's handbook, 25th edition, 1996 Industrial Press Inc
and knock off time is a hair past a freckle
or as the old one says.,
hair past a freckle coming up to a mole
What about the old "Micky whisker"?
Bit old school, young'uns probably wouldn't know what one looks like with everything shaven or waxed nowadays
action man u got it .. on my 15ft skiff im told ...easy the headie a bees dick all the time .. sheethand was from a 16footer
I think a "Gnat's cock" is a slightly more accurate measurement than a "Bee's dick".
Jeez Cisco that is showing your age somewhat. GC was lost to the archives before the Whisker was usurped by the c$$t hair.
So a bees dick is a single unit of measure, so you could have two bees dicks would make a _____? 
And a bee with two dicks would just be silly
isn't that ...." A Gnats nasty " 
or is that South Australian 
and therefore dosn't count for much
or is that South Australian
And a bee's dick on a cold day is 3/16ths of the average bee's dick. And we are talking about width, not circumference or length.
And if its a tight fit as we say in paving, it fits like a thumb in a bum.
So when one connects " the Bee's Dick " to the " bloody great wheel " ,
what has one got there, inertia or kinetic energy, or maybe just a bang, like a
dunny door.
