So yesterday we went up to see a boat restorer in upstate NY.
VERY nice guy. Anyway, while talking he reminded me that
I need to run a ground wire from my steel gas tank to the
engine or other ground point. ~ I'm sure this is a good idea
that can't hurt, but I'm just wondering:

#1 - What exactly could happen without that. I assume it's that
a static electric charge could build up on the tank or on me...and
when I touch the gas cap a spark happens in the tank?

#2 - Is the real purpose of the ground to the engine is because
the engine is grounded to the battery or is it because the engine
is connected to the drive shaft which is in the water (true ground).

#3 - What happens when the boat is on the trailer? Then none of
the boat is grounded....It's setting on wooden bunks and on rubber
tires? Couldn't I still get a spark then? ~ It's like a car...that has a
gas tank, but it's not grounded since it all sets on rubber tires?

#4 - Lastly, do the hoses at gas stations connect to ground? The
hoses appear to be rubber but I suppose maybe they are special
hoses with some ground wire embedded in the rubber to take
away any static charge ??

THANKS
Gary