It's not uncommon to find that an AP in a marina isn't functioning properly.
There is also a potential problem when there are multiple AP's with identical SSID. The Groove will choose the SSID with the strongest signal, not necessarily the one you selected. If 2 of the AP's have close signal strength the Groove can jump from one to the other as the signal strengths vary. This can prevent getting an IP. There is a Wireless "Station Roaming" setting that is by default enabled. I normally change this setting to "disabled" to prevent jumping from one AP to another.