Apple Event: May 7th at 7 am PT
We boat with 2 other families and would like to be able to stream our iTunes music to the stereos on all three boats at the same time so we can all listen to the same music while docked together. How can we do this?
Aside from the fact that you are attempting to do this across a number of boats, this seems reasonable that it could be approached similar to having stereos in multiple rooms in a house. iTunes can stream to multiple AirPlay Speakers (AirPort Express or Apple TV) simultaneously. Typically you would have each Express join an existing wireless network so that they are all on this same network for streaming.
You don't mention anything about a need for Internet access and it is really not required for streaming anyway. One option is to set up one Express to provide the wireless network, and then, have the other two join it. Network clients connected to this same wireless network, that are hosting iTunes, should now be able to stream to any or all of these base stations.
Please check out the following Apple Support article for additional details.
Streaming to multiple stereos at same time
