In the market for a mechanical dive watch with an analog thermometer? No? Well perhaps you will be after reading this review. Or at least you’ll appreciate that there are still some interesting new things to see in the world of mechanical timepieces. One of my biggest problems with mechanical watchmakers today is the total lack of effort in trying to create new (or fresh) complications and features. Too often we are presented with the same complications again and again, without much variety. Yes, chronographs, GMTs, and calendar watches are useful, but how many of them can any one collector own? Ball is among the few watchmakers to produce watches today with mechanical thermometers in them, and among these already rare models, the sportiest is the newly face-lifted Ball Engineer Master II Diver TMT.

Let me be clear that mechanical thermometers are not novel complications in wristwatches. I’ve seen pocket watches from the 18th century that have them. A thermometer was in fact a very useful complication because changes in temperature affected the timing results of early timepieces prior to the development of less temperature sensitive alloys. In our contemporary landscape most mechanical watches don’t have thermometers for the movement’s temperature because it isn’t very useful. Accordingly, the purported purpose of the thermometer in the Engineer Master II Diver TMT isn’t about movement regulation or monitoring, but it’s generally designed to allow you to measure the temperature of your environment – with a few catches.

Ball’s thermometer system is patented and displays a simple to read thermometer gauge on the dial in either a Fahrenheit or Celsius scale. That means each buyer first needs to make the decision concerning what scale measurement system they want. Since I live in the United States and we are rebel (Imperial) holdouts, this is the TMT with the Fahrenheit scale.

The biggest issue with the thermometer system is that it exists locked inside of a case designed to be water-resistant to 300m. If a change in air temperature causes the thermometer hand to go up and down, then that means the temperature inside of the Engineer Master II Diver case needs to change and level with the ambient air temperature outside of it. Does this need of the thermometer contradict the function of a diver’s watch case whose purpose is to keep air, water, and dust out? Yes.

The reality is that while the Engineer Master II Diver TMT is on your wrist, you’ll see almost no changes in the thermometer hand. Resting at an almost permanent 70 degrees, I originally thought the hand was broken on this watch. In fact, I have had one of these watches with a broken thermometer so I had some reason to believe that. Taking the Ball watch off my wrist, I knew that it would take a very long time for the thermometer hand to change. Again, this is because the air inside of the case needed to match the outside ambient air temperature. No easy task in a watch with all these gaskets and protection from the elements. So I put the watch in the freezer. Alas, the thermometer hand moved.

The message here is that if you are going to use the thermometer function for a lot more than idle conversation with other gear heads, you’ll need to first plan on taking the watch off of your wrist, and then wait a fair amount of time until temperatures inside and outside of the watch stabilize. Remember again that this can’t be done very well while the watch is on your wrist, because your own body temperature will greatly affect the reading. That is why on this watch it almost always shows about 68-72 degrees. That is some combination of the outside air temperature and my body temperature. This is a very good time to mention that a very similar model is available without the thermometer complication or with a GMT hand as well.

But the thermometer (TMT) version of the Engineer Master II has the most personality behind it, right? In the scheme of collecting interesting watches, we have a tendency (at least I do) to find unique and original stuff. So something like this otherwise straightforward and useful dive watch appeals to me – regardless of things like latent non-utility. The TMT version of the Ball Engineer Master II Diver also happens to be the best looking among them. Ball currently offers the TMT in three different dial colors including this deep blue and orange model; as well as black and white, and blue and yellow. The case is a comfortable 42mm wide with stubby lugs, so it sits modestly on most wrists. The case is just under 15mm thick and again, water-resistant to 300m. Over the dial is a lightly domed sapphire crystal which is AR-coated and doesn’t have too much glare.