Join Date: Sep 2009
Posts: 1,018
The "best" thing to do would be for the marina owners to re-position, turn up power, and/or get a better antenna. Based on nothing, I imagine they probably won't.
Since this would be for your phone (and not a stationary device like a desktop PC), your other option is to get a wireless repeater or range extender. This option can be suboptimal because it can negatively impact everyone else that uses that wifi. If you do end up going this route, try to get an extender/repeater that receives whatever channel the marina owners' wifi is on, then repeats the signal inside your boat on a different channel. That at least used to be a harder to find device, but it may be a bit more common now. That would mitigate negative impact to others.