When the mainsail is raised on a sloop, the sail itself holds up the boom. As the mainsheet (and optionally, a boom vang) pulls down on the boom, along with gravity, the sail is pulled taut. But when the sail is lowered, the topping lift on most sailboats holds up the boom. Otherwise the boom would fall down into the cockpit, becoming a hazard to people there and stressing the gooseneck that connects the inboard end of the boom to the mast.
Most sailboats have a traditional topping lift to perform this function, whole some boats use a newer rigid vang to hold up the boom. Shown in this photo is an adjustable topping lift from the outboard end of the boom to the masthead. (The mainsail is reefed in this example.)
On some boats, the topping lift is fixed, having been set to hold the boom up when the sail is lowered but not so tight that it pulls the boom up when the sail is raised. For sailing, the boom should drop low enough to pull the sail tight. Often the topping lift is adjustable, however, allowing the sailor to raise the boom higher out of the way with the sail down and to ease the process of reefing the mainsail.
Go to the next page for adjusting the topping lift.
