I should have said my boat dock, I have 3 other sonos zones in the house, but this would be on a wifi extender network - would also like to be able to have them on the same contoller as the other zones but not sure how that works. 

What kind of ‘extender network’?

Actual WiFi extenders aren’t supported by Sonos; they cause multiple issues for intra-LAN communications. 

WiFi meshes are supported, as are hard-wired access points. 

All Sonos devices and controllers need to be on the same IP subnet.

Maybe consider a Sonos Roam, or the larger portable Move 2 (recommended) - they are each rechargeable & water resistant. The Roam last 8+ hours and the Move 2 lasts up-to 24 hours on one battery charge. Both will auto-sleep/power-off when not in use and if the WiFi extender does cause you any difficulty, then you can perhaps Bluetooth-pair the speaker to your mobile/tablet and stream music to it that way.

Heres a link for further details…

https://www.sonos.com/en-gb/shop/portable-speakers

Don’t use extenders, in any shape or form, for connecting Sonos players to a network. (It’s okay to use controllers on extenders, though they can occasionally still hiccup.)

If Sonos detects any extender-connected players it will complain bitterly whenever a group is set up, even if the group doesn’t include such players.

Thanks - I have a wavelink extender and it shows up as a seperate network? I dont know that much about how they work or whatever - I’m either on the router network at the house or the Wavelink one - it shows up as a differnet system.  For my phone and PC, I’m either on one or the other.   If this makes any sense. 

The Sonos speakers won’t be able to communcate with each other between your two networks.  Not sure how far your dock is from the house, but I would look into getting a single mesh network to cover your house, dock, and property inbetween.  Besides the benefit for Sonos, you’ll avoid have to switch networks your property and situations where your phone or other device ends up with weak wiFi signal.