Thanks MichaelB1969, please let us know what Beneteau comes back with!
I have an ST42 but am interested as well. More than a few of the underway fires that I've read about in diesel boats (and trucks) are turbocharger related. Overheating, exploding, oil leaks that catch fire, etc.
Given where that ST44 was, I'd expect that they had been running at high RPM cruising along for a while.
When cruising, especially at higher RPM for longer periods, I pop into the engine room every couple of hours with a temperature gun and do some cross checking just for peace of mind. When I took my "Ask Captain Chris
" boat systems class, he suggested doing this and I found that my temp gauge at the helm is off by about 5 degrees low on port.
I take readings from both engines: Transmission, Exhaust Manifold, Turbo, Top of Engine, Middle near the injectors, Oil Pan. I can also read the starboard alternator without going down between the engines so I check that as well. The two engines typically only vary by about 3-4 degrees point to point.
My base temps on the top of the engines, injectors, and exhaust manifold run around 145 - 150 degrees, alternators 130, oil pan runs 150 - 160 degrees, and top of the turbo runs 170 - 180 degrees. So the turbo is the hottest item on the engine.
I did this a few times on a couple of day trips to get the averages at both high and low rpm for extended periods. Interestingly I found only about a 5 degree difference running at 1200 RPM for two hours and running at 2800 RPM for two hours. I keep a little cheat sheet on the engine room hatch so that when I read, I can quickly compare.
Note: If you are going to check your temps underway, I suggest spending a little extra and getting a good quality infrared temperature gun that has a high optical resolution like 10:1 or 12:1. This will give you a small reading area so you can shoot from the engine room hatch at a distance, rather than climbing into the engine room while underway.
I use an Etekcity Lasergrip 630
that has a 12:1 or 8:1 adjustable. Very happy with it. Got it from Amazon for $26.00. This replaced the Harbor Freight $8 gun that I wanted to chuck overboard (but just put in the trash to follow my garbage plan)
A couple of other interesting experiments with your temp gun are:
Confirm fuel level in the tanks. My fuel gauges were not working for a while, so after running for an hour or two I could shoot the side of the tanks (visible in my engine room) and see where the fuel level was. The hot diesel re-circulating back into the tanks was measurably warmer when reading the tank walls so I could get a good eyeball on the fuel level.
Also, check the temps about 5 minutes after you turn off the engines. They spike for a few minutes after cooling water stops circulating. The block on mine get's up to about 180 degrees. Not sure it this has any meaning, but I found it intresting. It feeds my inner Geek!