The idea of a spreader is to take the compressive load you describe. I
would not worry about 500 lb. on the gunwhale of an able boat. Think of the
load on a heavy skiff when you roll it over for bottom painting!
Dave
"Brian Bonner" wrote in message
. ..
I have a 40 aft cabin Silverton with 14' beam. Boat weight is 26000 lbs.
The yard plans on lifting it with a spreader that puts the two slings 12' 6
" apart across the beam. I calculate that the horizontal force on the
gunwhale to be almost 500 lbs at eeach point on the slings where they touch
the gunwhale. I am looking for opinions on this arrangement.