You must provide credit card info before finding out if there is space available for your requested time slot.
Your slip number is given to you with no accompanying map to show you where it is. The instructions tell you to to reference a diagram that is in the window of harbor office. So you have to find a place to tie up temporarily, get out, find map, go back, untie and maneuver to your slip. And this is while operating my boat alone. Luckily there was a dockhand available for some of my stay but that was unusual. No staff was available for help or questions until late June.
Dealing with an online service while operating a boat is very awkward and nonsensical.