The boat dock is close to the entrance at HS and the bus depot. It shouldn't take you more than a couple of minutes to walk there. If you stand facing the bag check area, with HS in front of you, you will see where you need to walk to the boat dock on your right. Have you checked what time HS closes on the evening you are going to B&C, the boats don't run all night so if it has an early closing time the boats may have stopped running. You could actually walk it but that would take a good 20 minutes or maybe more. The other thing to consider is that if you have just missed a boat sometimes it can take a while for another one to arrive. Unless HS is closing in which case there will be plenty of boats. Hope this helps.