During the first week of the season I looked up and saw that the mooring light (you turn it on when you are anchored or moored for the night) at the top of the mast was flickering. I instantly knew that it was the bulb needing to be replaced. Of course I had an extra bulb aboard, but I ordered some more from SuperBrightLED.com to replace my backup.
Once I had someone to help I was hauled up the mast and had the bulb replaced in a minute and after testing it down I came. One thing I told my friend, who is the chef on another boat, is to always let lines out hand over hand and not let it slide through your hand becuase you might get rope burn.
Another thing of note is that my mooring light is a cool one that has a sensor and shuts off when it is daylight. This means I turn my light on at the begining of the season and do not turn it off again until the end of the season and the sensor saves power during the day. It is so much better and I was never one of those people rushing off at 6pm because I forgot to turn my mooring light on. Adding a LED bulb means that the light is brighter and uses around a quart amp of power an hour.