Where's the sheeting?
I understand ther are different types of booms. One is built for sheeting via a traveler over the cabin enclosure, and this of course would have the sheet attached--say mid boom or so. The other boom type has sheeting at the end of the boom. A boom built for end boom sheeting may not be strong enough to take sheeting at its mid-point, thus the curve. I have no other specs to determine each type of boom strength.