Where is Highbar Harbor?
With WiFi there are many variables one being DSL some marinas are still using T1's if you think DSL is slow try a T1 connection with other users. I prefer a marina use Cable business class internet. To keep everything legal I would not use an AP that didn't have a legal disclaimer page where the users 1st log in and agree to the Terms of Use then are redirected to the internet. Also with high power APs the installer needs to certify the total system power not exceed +36dbm (4 watts) this includes every component in the system from the AP, coaxial cable losses and the serving area antenna gain. This is called Point Multi Point it is in the FCC rules under part 15 the rules must be followed. Recently in PR AT&T was fined $25k for exceeding this limit and also interfering with a TDWR airport radar system.
As far as IP based cameras if wireless they should be used in the 5GHz band or they will or can kill both your RF path and backhaul speeds.
For an IP based camera on your boat I recommend not running that through the marinas WiFi but a cellular router like the Ericsson W25/35, Kyocera KR2 or various MiFi units available from the cellular carriers.
For good radio path speeds you need a unit similar to the ROGUE if your RSSI isn't -75 and SNIR of 20 or higher on the boat.
You can download a free survey tool (Network Stumbler) that uses your computers WiFi card to show you all 802.11 APs and Routers from the location.
So to wrap it up if the marinas WiFi can't deliver -75dbm to the device then the Access Point and antennas need to be upgraded.
The boat also has some play in this because I would suggest a separate WiFi unit be installed on it and it feeds a switch router in the boat for rebroadcast below its deck. This is a balancing act you don't want your boats local AP to override the outside bridge router (masking the land based Access Point).
This all can be done with off the shelf business grade equipment if you are good at programming. If your not well versed then you need Marine Grade equipment Wave is only one of many brands of WiFi equipment for the marina and the boat.
Les has Digital Yaht and Syrens on BoatFix that sells really good equipment as well but you still need the Marina to have a decent business class pipeline to the internet, a professional survey and installation.
WiFi unlike Cellular is not a subsidized industry so good equipment for the AP (marina) and the boat (bridge/router) isn't cheap.
I personally prefer Wave WiFi but Syrens and Digital Yacht are also good equipment.
Bill