Many trucks have auxiliary power units (APUs) -- essentially small generators -- to power the AC and other house loads at rest stops. Some states have anti-idling laws.
The coolest recent development in marine propellers is toroidal propellers which are now commercially available and seem to perform significantly better than standard propellers: https://www.sharrowmarine.com/
Interesting! I am familiar with this space as we developed a software tool [0] to optimize packaging based on 3D packing technology we developed. If it is relevant to you, happy to chat!
No need to apologize! It was totally rational to assume that these two events were unrelated. It is a wild sad story and we'll likely learn about the motive over the coming weeks. This story hit me particularly hard as I live about a 3 minute walk from the victim's house in the Brookline area.