Go

Avoid the smaller turtlebox, go for the grande. It’s my current go to boat/outdoor speaker.  I’ve had multiple JBL boombox/party box’s and both the soundboks 4 and Go(loved both) but the turlebox grande fits the loud and portable niche well. 

Turtle box Grande. I have had the JBL party boxes, boombox3, wking, soundboks 4, SB Go, and no the turtlebox. The go was the best sounding in that environment, but lacked  being waterproof and salt spray long term was going to be an issue. The grande is 90% of the go’s sound while having better battery and a smaller footprint. There ARE other speakers that sound better, you’re not going for that, you want loud and tuned to cut through wind.  Turtlebox is very gimmicky/lifestyle as a brand and the OG turtlebox sounds terrible, but they dis make a good product with the Grande.

We did unforgettable after hour parties already - and when two Soundboks met, even better. But yes, I'd love to hear both / all five(?) systems in comparison. And in a better world, they would be cross-compatible anyways.

Soundboks Go if you want something more 'portable'. Super loud. Marshall Tufton more portable and still very loud.

You can expect +10h on the soundboks if played at high volume. But partybox should be similar. They both will reduce over time 😃

If you really value the battery, you have the soundboks one as way better for being removable. I'd buy a spare and you have easily continuous play - just have to charge one whilst the other plays. If you go for a charge station ensure you get a portable station with a pure sine-wave AC outlet and ≥240 W continuous output to power the speaker reliably. Make sure the station can sustain enough wattage — for music playback (with lights), allocate around 200–300 W to be safe. The soundboks has a great capacity battery, but at high volume it does drain - as expected.

Check out the Soundboks Go. I have the full size Soundboks and nothing else even comes close although it is a bit big and heavy.

I have 3 Soundboks speakers, the SB2, SB3 and the SB Go. They all do very well for movies. Matter of fact they might be exactly what you're looking for, because they go extremely loud and don't have that deep Partybox bass. So here's my last suggestions, the [Soundboks Mix](https://soundboks.com/products/soundboks-mix)