Yes, basically works in the same way as a dial-up internet connection.
The bluetooth dongle which you plug into your laptop connects your laptop to your mobile phone. You then just need a dialup account with an internet service provider (most will provide access on a pay per minute basis) and you are away. It is of course a slow connection, and potentially expensive for long periods of surfing, but if you can live with that it’s OK.
Of course many marinas now provide wireless access – again you have to pay for this, but if you have a wireless enabled laptop, or buy a wireless card for your laptop, this will provide you with a much quicker connection and cheaper in the long run. No help in the middle of the channel though 😆