you are experiencing a little harbour panic - don't worry you are quite safe in the marina and unlikely to do any damage more than a scratch or two and as for getting self conscious in front of spectators just get over it -

go down to boat on a quiet day - start engine, undo the warps in neutral, get back on board and pouther in gear and take her out for a potter around teh moorings and go back in. slowly

- best to do this single handed and then there is no one else to blamne if it all goes wrong ....

if the engine fails throw out the anchor when the water gets shallow and phone for help -

stop arsing about and get on with it -