A Tech Tool You Need - Digital Laser Thermometer

We were headed for Gibraltar, weeks of passagemaking across the Atlantic. Everything was running fine, and the crew remained relaxed and comfortable. And our rotating watch system gave each of us the opportunity to get to know one another. Great trip with great memories.

Somewhere during the passage, the owner and I were in the pilothouse, the rest of the crew asleep or elsewhere. He asked me in a somewhat hushed tone, "Your magazine always talks about hourly engine room checks while underway," he asked quietly. "What exactly am I supposed to check?"

Engine room 2.jpg

It was a fair question. Back in the days before electronic engine controls and monitors, machinery could leak, hoses crack, clamps vibrate off, or fasteners loosen. And no one could see the impending problems unless one stepped inside the engine room.

Today's engine rooms are very well monitored, to the point that if a hose bursts on the engine's cooling system, the helm knows instantly that something is amiss. But before such technology was common, the crew was responsible for monitoring duty, and no engine room camera could look, smell, feel, or hear anything out of the ordinary.

Nowadays, especially when coastal and inland cruising on a trawler and relaxed schedule, many cruisers perform a full check of all fluids and levels and general inspection in the morning before they head off for a day on the water. That attitude doesn't fit the 24/7 demands of an offshore passage.

Experienced broker and good guy, Jeff Merrill, wrote a nice article in Ocean Navigator about how he teaches a new owner how to inspect an engine room. Jeff puts pieces of blue painter's tape around the engine spaces, identifying the many things to keep an eye on when looking over the major systems.

One tool that I find very helpful to have aboard is a handheld digital non-contact thermometer. I have two now, as they are very handy and not very expensive. I really like the Fluke Model 62 Mini IR Thermometer shown below.

The Fluke Model 62 Mini has been replaced with a newer model, but they all perform the same functions. Every boat owner should have one in the tool bag.

The Fluke Model 62 Mini has been replaced with a newer model, but they all perform the same functions. Every boat owner should have one in the tool bag.

Its feature include the following (from the Fluke.com website):

  • Single point offset laser sighting

  • Best accuracy in its class: + 1% of reading

  • Holds temperature readings for 7 seconds

  • Dual displays shows current and MAX measurements simultaneously

  • Backlit display for poorly lit areas

  • Comfortable ergonomic handle with protective rubber boot for added durability

  • Wide temperature range from -30° to 500°C (–20° to 932°F)

When you pull the trigger on the thermometer, a laser dot and/or pattern appears on whatever you have it aimed at, and the unit measures the radiant energy/heat in the infrared band. The temperature shows up instantly on the small display. It is very easy to operate and can switch between Celsius and Fahrenheit readings. Some models monitor a range of temperatures while the trigger is pulled, showing the maximum temperature when you release the trigger. To learn more about the science of this see an explanation of this technology from Fluke:  (http://media.fluke.com/documents/4213876_6003_ENG_A_W.PDF)

There are any number of things in any engine room that can be measured, which is a good way to notice when there are anomalies. By taking a permanent marker or dab of non-reflecting matte paint, and marking a round dot at a specific location on an exhaust elbow, for example, you can record the "normal" temperature recorded at the spot with the handheld thermometer and measure that spot again from time to time (from the same distance away as well) with the digital thermometer.

Generally it is best to get as close to the spot you want to measure as is safely possible, maybe 10 or less inches away. On some models there is a distance-to-spot measuring area graphic imprinted on the top of the instrument. On my Fluke 62 Mini, it shows that when held 10 inches away from the spot, the measuring area around the laser dot is one inch, and that measuring area grows larger the farther away you hold the gun. At 40 inches away the measuring area around the laser dot is four inches. My other thermometer has a ring of laser dots around the central dot when you pull the trigger. As you move back with the thermometer, the size of this laser ring increases to show a wider area being measured. 


With practice and routine use, you will know right away if the temperature reading changes beyond "normal."

The list of your baseline "normal" readings should be recorded on a chart and hung on a clipboard in the engine room so you can compare new readings with these baseline temperatures. Things worth recording might include (but not limited to):

  • Exhaust elbows

  • Oil pans

  • Transmissions

  • Thermostat housings

  • Coolant reservoir/expansion tanks

  • Heat Exchangers (perhaps a spot at each end to compare)

  • Exhaust hoses

  • Stuffing Boxes/Shaft Seal Housing

  • Auxiliary Pumps

I have also used this handy thermometer to measure cooling and heating temperatures coming from the boat's air conditioning outlets in the living spaces, check how cold the refrigerator and freezer are, even to check cooked food in the galley.

A quick Google search identified numerous brands that pretty much all do the same thing. From the looks of it, so many of them look so  identical, except perhaps for handle color and labeling, I suspect they may all be manufactured by the same company and marketed and sold by the name brands. I have had great, reliable service from my two units, the Fluke I already mentioned and a larger one by Raytek. Both run off a nine-volt battery which seemingly lasts forever.

The Fluke thermometer, a flashlight, safety glasses, and a roll of paper towels remain just inside the engine room door, while sound-deadening ear muffs are nearby outside the engine room.

Oh, and that owner and I spent a great deal of time in his engine room, and by the time we arrived in Gibraltar, he was very much in love with his engine room and his new intimate relationship with its machinery and systems.