Originally Posted by Windseeker
. . . I have a boom lift line that is 3/8" dia double braid. Can I replace it with something smaller like a 5/16" or a 1/4"??? I never adjust this line. I don't even know if I am supposed to. It doesn't seem to carry much load. I perceive its only purpose is to prop the boom up for convenience. . . .
Thanks in advance.
I suppose you are talking about a "topping lift" or a line that runs from the mast head
to the end of the main boom. With the mainsail
stowed or "no up", the "topping lift" supports the boom and keeps it from falling down into the deck
After you have raised the mainsail
fully up you may notice that the boom lifts a little upwards. Some don't so this is where the topping lift comes in to play. With the main sail fully up you slacken the topping lift to allow the main boom to lower and pull the clew of the sail down tightening up the leech of the sail and improving it shape.
Another use of the topping lift is to "depower" the mainsail. By tightening the topping lift you raise the boom a little which allows the mainsail to twist or the leech to go slack. This allows the mainsail to "dump" some of the air that is filling the sail. This effectively "de-powers the mainsail and is useful when "reefing" the mainsail is difficult due to weather
or other factors.