This streaming speaker from Technaxx can be brought on your boat trip. This model comes in a variety of colours.
From Amazon
Technaxx Mini Musicman 3 W portable speaker, 1-way, 3 W, 150-18000 Hz, 4 ohms, 10% wired, black, 3527, 1 piece
Conrad Electronic
Technaxx MusicMan Mini Mini speaker Aux, SD, USB Black