Question

cranes and derricks installed on floating surfaces must have a ______ placed where it can be easily seen by the operators. personnel platform guardrail boom angle indicator hoist drum

Explanation:

A boom angle indicator is crucial for operators to know the boom's position, which is essential for safe and proper operation. A personnel platform is for carrying people, a guardrail is for safety around edges, and a hoist drum is part of the lifting mechanism but not something that needs to be easily seen by operators in this context.

Answer:

Boom angle indicator