What is Thermal Imaging?

Thermal imaging is a technique used for detecting and measuring variations in heat energy and transforming that data into visible signals which can be recorded photographically. This technology is used to analyze the seaworthiness of a vessel, or to see alterations to a vessel that cannot be otherwise seen. The thermal imaging experts at AAC Marine Surveyors use this technology to identify problems that are potentially hazardous before it's too late, or to let a prospective buyer of a vessel know if there are any structural, electrical, or mechanical problems that can't be seen before they purchase the vessel. It can detect underlying abnormalities which cannot be detected otherwise.

This is the back of an electric distribution panel in a 40-foot boat. Visual inspection shows that the wires are intact; wire insulation and terminals are free of burn or scorch marks. Infrared view shows that one of the wires in the bundle of wires is much hotter than the others. The heat and resistance in this wire caused its magnetic circuit breaker to trip intermittently.

Thermography

Definition of thermography: All objects contain thermal energy and interact thermally with their environments. One way which heat can flow is called heat radiation or infrared. This heat energy travels by electromagnetic waves. The infrared camera records an image of this heat energy. The science of acquiring and analyzing this thermal information from thermal imaging devices is known as infrared thermography. Anywhere a thermal imaging pattern or abnormality exists thermography can be applied. A trained individual interprets and analyzes these images to produce a report that documents the results of the thermal imaging scan.

Irregular dark spots on thermal imaging represent high moisture conditions in the cored FRP laminate.  These are not visible to the naked eye.
The radiation measured by the camera does not only depend on the temperature of the object, but also the emitted energy. Radiation also originates from the surroundings and is reflected from the object. The radiation from the object and the reflected radiation will also be influenced by the absorption of the atmosphere. An infrared camera detects the radiant heat from a surface, based on the surface’s temperature, emitted energy, and reflected heat radiation from the surroundings. Understanding how that heat got there is essential to making proper thermographic interpretations. To measure temperature accurately, compensation for the effects of a number of different radiation sources is necessary. In addition, the proper distance yields an accurate measurement result.

Bad breaker connection on main panel of a large boat.  This is a serious problem that is hard to see.  The infrared scan instantly reveals and pinpoints a loose and corroded electrical connection.
Thermal imaging is a must for determining the stability of any vessel with coring in its construction. An expert in thermal imaging must know how to operate the equipment effectively and accurately interpret what is seen based on an understanding of the material being surveyed, as well as an understanding of any variables that could contribute to a misrepresentation of the data. The thermographer must also be able to recognize thermal patterns as they relate to electrical and mechanical systems.

Thermography can detect alterations made to vessel structure.  IR Image on right shows a plate welded to the hull.
The subjective statements in this report are the personal, unbiased professional analysis, opinions and conclusions of the thermographer. The thermographer shall be held harmless for any subsequent conditions arising since the findings are valid only at the time of the inspection.

High injector temperatures can indicate plugging.  A plugged injector will show very hot on an infrared scan - pinpointing the problem before it becomes a serious hazard.