need to get your laptop connected to the net first. 2 choices,
1. mobile phone, slow connection speeds so might no be much cop for web casting
2. WiFi card in a laptop, you need to fish somewhere in range of a WiFi server tho, which is probably nowhere near the sea!
I have done something similar, Apple Airport technology, now has a range of about 2 miles, so you need someone within that distance from you intended fishing spot, with a mac and an airport base station, and a mac laptop with an airport card in, and a camera. If you did it this way, it would take all of 5 minutes to set up - Apple have built all this into the latest versions of the OS. Basically plug a camera in (pretty much any camera) and turn it on, choose a url for your cam page and off you go - no drivers or config to do. I did a web cast earlier this year for one of my clients, they launched in a poncy hotel about a mile from their offices, used airport and it worked great, the ize of the movie and the frame rate is dictated by the speed of connection from the airport base station and the net. The airport base staion to card speed is over 50meg per second