[AdrianB1]

At least for airplanes you don't have to transmit the position when the plane does not fly. The article says the boats must do it 24x7.

[eesmith]

There's a power-down exemption for boats which are continuously out of the water or in port for more than 72 consecutive hours. https://www.ecfr.gov/current/title-50/chapter-VI/part-622/su... .