The Power Equation in a Sailboat or Other Marine Application

From initially sizing your marine electrical system to determining the draws of specific appliances, understanding the underlying power equation is key to having a properly built system. An undersized system can quickly leave you stranded on the water without ample power to get you through your day. Once you understand the power equation, it’s easy to quickly calculate the draws of your appliances and be prepared with plenty of power.

How Do You Calculate the Power of Your Marine Electrical System?

Whether you’re sizing out a brand-new electrical system or just trying to find the power draw of a necessary appliance, understanding the power equation is essential. Although it’s a simple calculation, inputting the correct numbers for each variable is key to ensuring your marine electrical system is sized properly.

Power, measured in Watts, is equal to the current multiplied by the voltage, where “I” represents the current in Amps and V represents the volts. If you’re interested in determining how much current is running through a particular wire or being drawn by a specific appliance, just rearrange the equation to solve for current. In this case Watts divided by Volts is equal to Amps. So, if you have a 1,000W microwave on your boat that is being run through an inverter and drawing power from a 13V battery bank, 76.9 amps of current is being pulled by the microwave.

Want to Learn More?

Check out the full Marine 101 series on our YouTube channel or through the Academy page on our website. For further questions or help designing the perfect marine power system, our technical sales team would love to help! You can reach by calling (855) 292-2831 or emailing [email protected].