“derrick boom”簡單造句，derrick boom造句子

1、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.

2、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.