The outer layer of the transom is 3/8" thick . Easy enough to bend on without
steaming , but still stiff enough to need a bit of brute force and ignorance to
bend it around the curve for fitting .
After the fit is right , the plank is coated with glue on the inside face . The
plank is then screwed in place with a few screws to locate it . A strip of mastic
seal is then placed around the perimeter of the plank , and the entire plank
covered with a sheet of 6mil plastic . A hose is then sealed into the space
underneath the plastic and all of the air sucked out with a vacuum pump . This
technique is called vacuum bagging . The principal is that because the
atmosphere that we live in exerts about 15 lbs. per square inch pressure on
everything . If you remove that pressure i.e. create a perfect vacuum the
plastic is pressing down with 15 pounds force on every square inch . When you
consider that the area of the plank is about 8 square feet , or 1152 square
inches and that a vacuum of 8 lbs. per square inch is being reached . That is a
total force of 9216 pounds holding the plank onto the transom . The vacuum has
to be maintained until the glue dries I generally assume that the glue is cured
when the door knob is no longer sticky . ---In the mean time I keep my fingers
crossed that the old milking machine pump doesn't die while the glue is half
cured
The castings for the struts are also machined and water lubricated bearings
fitted where the shafts go through .
