Laurence,
I am following up on Russ S. response to you.
Yes, years ago the racing sails were make as long as possible on the luff for max. sail area. We were using a "Preventer" system to hold the boom down when going with the wind. This had to be changed side to side when you jibed.
Recently the Boom Vang has been used and is much safer in all points of sailing. This required the Main sail luff to be cutdown to no more than 23' in length to give the needed angle to make a boom vang work. The sail is cut from the bottom of the luff to the intersection of the foot and leech of the sail. This means you are cutting a narrow triangle off the bottom of the main sail.
I have had several main sails cut and the cost was about $150.
Any questions, you can contact me directly NWattis@verizon.net
Good Sailing in 2021 and Beyond.
Newt Wattis
# 2604
"My Lightning"