jkliegman has a right Idea! Her's another one.
On my Gulfstar 41', I run a continous
line with a snap
shackle at each end from the end boom area to a
cleat foreward and back to the end boom area on the other side. It merely runs through the base of the bow
cleat, and is not made fast.
The snap
shackle on the lee is attached to the end of the boom, and the upwind end of the
line is made fast to a
cleat at the cockpit. The
line holds the end of the boom, not the middle and runs clear to the bow. To make a controlled gybe, unsnap the starting leward, pass the boom across under control, and snap on the new leward side; make fast the now upwind side. Its fast and done without leaving the helm. Keeps the boom from booming on your head.
By the way, used to have a chandlery in Brookings OR. Every year, at least one boat would come in with a buckled boom from using the vang as a preventer. Out on the real ocean, where winds are strong and seas kicking the stern around, you need to have an end boom preventer, or a big checkbook for boom replacement.