In article ,
"renewontime dot com" wrote:

All
merchant ships carry GMDSS and DSC radios, and if you hit the "emergency"
button on your DSC VHF it will -definitely- get the attention of every
bridge on every merchant vessel within radio distance of your boat. If you
get DSC, make sure you know how to use it properly.

Only those vessels that are SOLAS Required. (300 tons and up), and not
Tugboats of any size, no matter how big the barge is.

Me