Oct 24, 2019

Digital Multimeterstwo examples of common digital multimeters

Big or small, sail or power, gas or diesel, most of the boats that are encountered today have an electrical system onboard. Some are as simple as a pull cord turning over an outboard motor, others are a complex DC/AC panel aboard a cruising yacht. Whatever the case, if there are every any issues with onboard electrical gear, a multimeter is an essential tool to keep aboard. More important than keeping it aboard, is the understanding and the ability to use it effectively.

Understanding your boat’s electrical system (even in theory), and basic use of a multimeter can allow you to:

• Troubleshoot and repair problems when away from shore
• Diagnose problems without having to call in a repair tech
• Take on preventative maintenance tasks more confidently

First – a bit about electrical circuits. For the purpose of this article, we’ll look at DC circuits alone – They’re simpler, and found aboard more commonly.

A DC circuit can be likened to a garden hose running to a sprinkler. The tap allows water to flow through the hose, ending at the sprinkler, where the water is forced through. The Tap is your boat’s battery. The water is electrical current. The hose is the boat’s wiring, and the sprinkler is a ‘resistance’ (this could be a light fixture, a starter motor or a GPS unit: in short, the resistance is whatever the electricity is powering.)

The battery provides the force (voltage) that pushes electricity (current/amperage) through a resistance. In a simple DC circuit, the voltage will remain the same wherever it is measured. The current/amperage will vary depending upon the resistance (an appliance with low resistance – like a light bulb – will require less current that an appliance with a high resistance – like a starter motor.)

Multimeter Selector Switchhe selector switch of a multimeter showing the options to measure: voltage, ohms, hertz, degrees and amps

A modern digital multimeter is designed to measure each of these. It can measure voltage (in volts) current flow (in amps) and resistance (in ohms.)

Here are a few practical ways that this can be applied aboard your boat.

1) An incandescent light fixture doesn’t turn on.

First – test the boat’s battery voltage to ensure that power is available. The multimeter’s red lead should be placed on the positive terminal, and the black lead placed on the negative terminal. The DC voltage reading should be selected. The battery should read somewhere between 12 and 14 volts.

Next – confirm that battery switches, breakers and/or fuses allow current to flow to the light fixture. Assuming that there’s no obvious barrier, test the voltage at the light bulb (you’ve already tested voltage at the source – the same voltage should be seen at the appliance). Place the red multimeter lead where the base of the bulb sits in the fixture. Place the black lead on the casing that holds the bulb. The reading should be the same as battery voltage. If there is no voltage seen, it means that there is a break in the circuit somewhere and power is not arriving at the light fixture.

If battery voltage is present and light still doesn’t work, test the bulb using the ohms setting on the multimeter. The bulb itself is creating a resistance in the circuit and this can be measured. Place the red lead on the base of the light bulb, and the black lead on the metal side that sits in the casing. There should be an ohms reading showing on your multimeter. If the meter shows OL (Over Limit) this means that there is a break within the bulb and it won’t provide a resistance. Replace the bulb and the light should work!

Measuring Battery Voltagemeasuring battery voltage

2) The bilge pump stopped working

First – as before, test the boat’s battery voltage to ensure that power is available. The battery should read somewhere between 12 and 14 volts.

Next – test at the negative and positive wires at the bilge pump to see if voltage is present. This may mean probing inside the wires outer sheathing, or may mean cutting the wiring (meaning that you’ll need to add a butt connector once testing is done) to allow you to test. Test the for voltage by placing the red lead on the positive wire (brown), and the black lead on the negative wire (black). You should read battery voltage. If no voltage is shown, check the wiring, fuses and breakers between the battery and the bilge pump. If voltage is seen, but the pump doesn’t operate, check for a blockage in the pump, or evidence of overheating/melting. Repair/replace as necessary.

3) You can’t tell if your battery charger or alternator is working.

First – test the battery at rest using the DC Voltage setting on your multimeter. A charged and healthy battery will read 12.6V. Record that reading and turn the boat’s battery charger on. Ensure that it engages and is operating correctly. Test the battery again using the multimeter’s voltage setting. It should read 13-14V.

The same can be done with the engine’s alternator: Test the battery at rest, as in the first example. Turn the boat’s engine on and test the battery’s voltage again – the battery should read 13-14.5V with the engine running.

These are just some simple examples; there are a myriad of uses for a multimeter aboard – from trailer wiring to ignition and starting issues. In addition, there are many resources, articles and videos available online to learn more.

Andrew McDonaldAndrew McDonald is the owner of Lakeside Marine Services – a boat repair/maintenance firm based in Toronto. Andrew has worked in the marine industry for 12 years and is a graduate of the Georgian College ‘Mechanical Techniques - Marine Engine Mechanic’ program.

Questions or comments for Andrew? Email him directly via: This email address is being protected from spambots. You need JavaScript enabled to view it.

 

 

 

 

 

 

 

Related Articles

Wednesday, 09 August 2017 02:52

The moment we all dread. It’s a warm sunny day and you’re out for a cruise. Suddenly the boat shudders beneath you, pings, dings and clangs are heard and you realize that you’ve hit something...

Wednesday, 11 October 2017 05:00

If you walk the aisles at a boat show, visit a marine store, or stop in at a repair shop, you’ll likely be inundated with digital displays, vivid touch-screens, NMEA compatible devices, and...

Wednesday, 08 November 2017 04:38

Water has a funny way of making its way into a boat: through through-hulls, stuffing boxes, leaks, hatches, windows and portholes 

Tuesday, 12 September 2017 06:10

The moment we all dread. It’s a warm sunny day and you’re out for a cruise. Suddenly the boat shudders beneath you, pings, dings and clangs are heard and you realize that you’ve hit something...

Wednesday, 10 May 2017 00:43

Question: Can I buy generic automotive parts or products for my boat, or should they specify ‘marine’?

Tuesday, 11 July 2017 07:16

For most of us – this is the time to make the most of the boating season – launch and set up are done. Systems have been recommissioned. Let the fun begin!

Boat Reviews

  • Prev
Once again, Cruisers Yachts is leading the market for day boats with their new 42 GLS model that ...
Optimized sailing performance and comfortable living – a sweet ride. The expression that came to ...
This is such an exciting time in boating! While we feel very sorry for people whose health and ...
For many, the 2020 sailing year will be one to go down into the books as “different”. With delayed ...
What perfect timing! Beneteau is has just announced their new Antares 11 model for North America ...
Commodore’s Boats is a full-service shipyard with over 50 years of generational history and ...
The Oceanis Yacht 54, younger sister of the Oceanis 62, embodies the innovation that has always ...
Beneteau announces the launch of the latest addition to the Antares range! With a length overall of ...
I had been looking forward to a sea trial aboard the Greenline 33 because I was hoping it would ...
New at the end of 2019, the 58 Salon Express design features large windows to flood the living ...

CY Virtual Video Boat Tours

Virtual Boat ToursWe all love boats and nothing can break us up! So, what better way to spend our time than looking at interesting boats and going aboard in a virtual ride or tour. We have asked our friends at various dealers and manufacturers to help us assemble a one-stop online resource to experience some of the most interesting boats on the market today. Where the CY Team has done a review, we connect you to that expert viewpoint. If you can’t go boating, you can almost experience the thrill via your screen. Not quite the same, but we hope you enjoy our fine tour collection.

 

Read more about the CY Virtual Boat Tours....................

 

Cruisers Yachts 42 GLSBy Andy Adams

Once again, Cruisers Yachts is leading the market for day boats with their new 42 GLS model that premiered at the Fort Lauderdale Boat Show at the end of October. The concept of a large day boat is now a very well-established trend made possible by the amazing new power and efficiency of the latest four stroke outboards.

Buyers are looking for a different boating experience and we think that the 42 GLS nails it. Fast, handsome and versatile, the 42 GLS is designed for fun and adventure.

Read More

Destinations

  • Prev
In Part I, Sheryl Shard ended the story at June and the start of Hurricane Season when they were ...
You likely aren’t quite ready to travel yet, but we have our fingers crossed that we can all fly ...
Ontario’s best-kept secret, the Trent-Severn Waterway National Historic site holds the key to ...
Located on the sunny south shore of the harbour, the Marina is on pilings over the water, offering ...
The approach to the Chemainus Municipal Dock from Stuart Channel is straightforward and is ...
I leaned my head back into the water and floated easily. Having spent my childhood playing in ...
History: right after gym and just before chemistry class. Fifty minutes of naming the prime ...
On May 19, the New York State Canal Corporation today announced an updated opening schedule for the ...
If you have four hours to enjoy a fine tour of one of Canada’s most interesting waterways (let’s ...
Boom & Batten Restaurant is suspended over the water adjacent to the Songhees Walkway and ...

 

Bahamas - There and Back Again IIIn Part I, Sheryl Shard ended the story at June and the start of Hurricane Season when they were once again joined by friends.

This time it was Noel and Tracey Dinan, whose new shallow-draft Allures 49.5 was in build at the time, we headed north from the Exumas across the expanse of the Great Bahama Bank, dodging coral patches as we sailed to Eleuthera then Marsh Harbour, Great Abaco. Another commercial centre in the islands, we cleared out of the Bahamas here after provisioning for our offshore passage up to the Chesapeake Bay on the US mainland and out of the Hurricane Zone until mid-November...

Read More

Lifestyle

  • Prev
OK, stop the presses. This photo just came in from Beacon Bay. Clearly those folks know how to get ...
Back in the day, the publisher of a magazine would receive a bound copy of the year’s monthly ...
Boaters on BC’s West Coast have heard the story of the garbage pickers of the Marine debris removal ...
Skipper John “Drew” Plominski is hoping that lightning doesn’t strike twice. Plominski, whose boat ...
The Association provides a forum for exchanging information, tips and access an advocate on behalf ...
Kristin Cummings, Operations Manager at Beacon Bay Marina took this shot after the skies broke ...
Our Photo of the Week (two, in fact) comes from New Zealand where the second America’s Cup AC 75 ...
The Marine Debris Recovery Initiative (MDRI), a collaboration with the Clean Coast, Clean Waters ...
The International Joint Commission (IJC) is reviewing Plan 2014 and could use your help. The plan ...
The Council of the Great Lakes Region (CGLR), thanks to funding from Environment and Climate Change ...

Marine Products

  • Prev
On Monday, Volvo Penta announced the availability of their fully integrated assisted docking system ...
Perhaps the ultimate audio solution for boat owners, the JBL by Harman BassPro Go from Prospec ...
It only takes one foggy, disorienting day on the water to make a boat owner understand the value of ...
It’s a voyage everyone wants to undertake, but few get to make. The Whales of Lake Erie is the ...
Over the years I have had a real soft spot for the Jeep Wrangler line of models. Recently I had the ...
Wait no longer, the 2021 Rideau Canal & Lower Ottawa River PORTS Guide has returned! Purchase ...
The Tundra 65 is Yeti's most versatile cooler, just as adept at keeping catches cold as it is ...
Fireball self Extinguisher. It's a revolutionary self-detonating device designed to extinguish a ...
The problem with driving any full-size Pickup Truck or Sport Utility Vehicle is that when you are ...
Wait no longer - the 2021 Rideau Canal & Lower Ottawa River PORTS Guide will be available for ...