rolling a boat, or any other heavy object need not be a dramatic
affair. In my work place we regularly roll or move objects weighing up
to 4000lbs wiith just two people. if you are lucky enough to have
structural overhead beams then chain blocks are quick and easy, if not
you can often build some sort of a fram for very little money (sub $50
if you use scrap metals) and can weld. if you cant weld, buy a second
hand stick welder and learn. i bought my first welder for $50 and
after reading a bit on it was competent enough to make decent welds.
within a month i could weld high strenth suspension components for
competition jeeps. 5 years later im a structurally certified welder in
most positions for stick and mig. one you get a welder you'll be
surprised at how you ever get by without one. it is to steel what
resin is to glass. a million uses.

if you dont have these means or dont want to get involved then use your
head instead. levers and pulleys give a _tremendous_ amount of
mechanical advantage if you understand a few basic principles. If you
have a couple of strong sawhorses or plenty of loose lumber its
actually pretty simple to move or roll anything if you're not in a
hurry. I've pulled stuck jeeps out of rivers with nothing more than a
bit of rope and some lengths of pole found at a construction site down
the road. many of the greatest marvels of the world were bilt with no
more technology than this; look at all the enourmous stone statues, the
pyramids ;-)