Calculating power needs for your cruising boat is crucial for making sure your battery can support your equipment. Here are some simple calculations to ensure you have all the power you need, when you need it.
Summary
New cruisers don’t have to be surprised by how much electricity it takes to live comfortably on a boat. You won’t be find yourself short if you know how to make a few simple calculations.
Let’s talk about calculating your boat’s power needs. The key steps for 12-volt devices include:
- Find the power draw of the equipment. You will usually find it on the package.
- If the power draw is expressed in watts, convert it to amps.
- Multiply the number of amps by the number of hours you expect to use it.
If you’re looking at items that run on regular household current through your inverter, you’ll need to estimate a bit. Multiply the number of amps it draws by ten to approximate the 12-volt draw once it runs through your inverter–round up.
Once you know the power draw of the equipment you want to run, compare it against the battery capacity available to you.
For more details and real-world examples, listen to the complete podcast or check out How to Calculate Boat Power Requirements.
Today’s episode of The Boat Galley Podcast is sponsored by MantusMarine.com, maker of the Mantus anchor, now available in models with and without a roll bar. Proven to set reliably in the most challenging bottoms, the Mantus anchor digs like no other, making anchoring safer and boating more enjoyable. Mantus Marine brings to market practical, durable and affordable marine products, including: anchoring gear, scuba diving accessories, and rechargeable waterproof headlamp for hands-free lighting and solar charging Navigation light. Visit MantusMarine.com and see for yourself!
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Music: “Slow Down” by Yvette Craig
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Carolyn Shearlock has lived aboard full-time for 17 years, splitting her time between a Tayana 37 monohull and a Gemini 105 catamaran. She’s cruised over 14,000 miles, from Pacific Mexico and Central America to Florida and the Bahamas, gaining firsthand experience with the joys and challenges of life on the water.
Through The Boat Galley, Carolyn has helped thousands of people explore, prepare for, and enjoy life afloat. She shares her expertise as an instructor at Cruisers University, in leading boating publications, and through her bestselling book, The Boat Galley Cookbook. She is passionate about helping others embark on their liveaboard journey—making life on the water simpler, safer, and more enjoyable.
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