derrick boom

基本解释

Otherwise, adjust the derrick boom. Fix the shaft seat on top, and fix the shaft at bottom.
推動門扇應滑動順暢，否則調節吊輪的吊杆、上固定轉軸座、下固定轉軸。
The opening hatch cover method also not to be satisfied that using the warping head of cargo gear not through derrick boom open the hatch cover because using derrick boom is not safe.
開艙蓋的方法不令人滿意，起貨設備傳動輪彎頭在開艙時不穿過吊杆，原因爲使用吊杆不安全。
blog.sina.com.cn
The derrick boom rests to be renewed as Chief Officer requirement because the rests are too high and too thin and not safety for navigation. Also the deformed positions to be corrected.
吊杆支座應按大副要求換新，因爲支座太高、太薄不能滿足安全航行，同時需糾正變形。
racktom.com