Which is a recommended item to have for performing repairs on a vessel?

Having a multimeter onboard is essential for performing electrical repairs on a vessel. This tool allows sailors to measure voltage, current, and resistance, helping to diagnose issues with the electrical system. For example, if there is a failure in the navigation lights or a problem with the battery charging system, a multimeter can assist in identifying the faulty components or connections.

In contrast, while a GPS and chart plotter are crucial for navigation, they do not directly aid in repair tasks. A life jacket serves an important safety function by ensuring that individuals are protected while on the water, but it does not assist with the technical aspects of repairing a vessel's systems. Therefore, the multimeter stands out as the most useful tool in the context of repairs.