Which of the following is NOT a purpose of steadying lines?

The correct choice is based on understanding the primary functions of steadying lines in a maritime context. Steadying lines are primarily utilized to maintain stability and control of a boat during various operations, particularly when it is being hoisted or moved. They help ensure that the boat remains stable and does not sway or become unbalanced during transit, which directly relates to options A, B, and C.

Keeping the boat parallel to the ship is crucial for alignment during transfer operations (option A). Assisting in lifting the boat into the air (option B) involves steadying lines to prevent tipping as the boat is raised. Stabilizing the boat during transit (option C) ensures the safety of both the vessel and crew.

Lowering the load into the water (option D) does not align with the primary purposes of steadying lines. Steadying lines are not concerned with the act of lowering but rather with maintaining stability and control during lifts and transfers. Thus, option D is not a purpose of steadying lines.