NavList:

I have to admit that in 18 years of flying I managed to avoid a lightening strike.  The only time I was in a really bad downpour in TIKI with coincident thunder and lightening, I was more concerned about my own squidgy little body becoming a lightening conductor that for her negligible nav equipment (a compass, a sounder,  and a fag packet sized Decca working on lane-ident signals) being damaged.  At least the rain flattened the sea.
However, in worrying about our plethora of modern digital equipment, let’s not forget the basics.  What about the effect of the lightening strike or proximity upon the vessel’s hard iron magnetism?  In the days when dead reckoning was much more important, the effect of a lightning strike on an aircraft’s compass system was taken very seriously, both at the time and for months afterwards.  There was a laid down schedule of compass swings to be completed as the hard iron returned to what might be termed normal. 
Once clear of cloud, a basic knowledge of CN along with a peri-sextant or astro compass could help here in providing a heading check.  The effect on a small steel hulled vessel might be the same, and once more, a basic knowledge of CN and a pelorus,  or failing this, a sunrise or sunset heading check using amplitude tables might suffice to check the compass.  However, this might not be possible for some days.  In my opinion the main argument against using CN as a back-up is you need clear skies; no problem at 40,000’, but not always available at sea level.  Dave