Essentially, spring lines are just long dock lines.

Ensuring that your boat is in the same place you left it is a very important skill. There are also other factors to consider: depth under keel and surrounding area depth, tidal currents, low tide depth, other boats in proximity, wind speed and direction changes, type of bottom, and length of stay. All factors play into your anchoring decisions.

Sound signals are defined and prescribed in the Navigation Rules for International and Inland Waters. Sound has an advantage over light signals, in that it can be used when vision fails.

Like a water bucket, batteries have a specific storage capacity and must be refilled/recharged when their contents of energy are depleted.