Q: How many cruisers does it take to change a lightbulb?
A: 10. One to hold the bulb and nine to turn the boat. (© Pip)

That's not true of course. It takes at least nine. Two to watch and offer meaningless advice while you're up there. At least two to comment on the bulb you removed on the previous trip up the mast, purse their lips and say they don't have one like that. Plus the three others who ask you to come and do theirs as well. All these groups can be bigger, and indeed expand exponentially as soon as the job goes wrong.
Meanwhile, one of you actually has to go up there and change it, while the other one tends the safety lines on the deck.
Our deck light, which is about 10m up the main mast, doesn't see a lot of use, mostly just if it's a really dark night when we anchor, or to light us up really brightly if a fishing boat is paying too little attention to slow yachts in their vicinity. We installed it new in 2003, and it was checked when we had the masts out in 2005. This spring, it wasn't working, so it was time to take it to bits and see what could be done.
In the end it went very smoothly. The ferremente couldn't help, but sent us round the corner to the car suppliers, who took one look and sold us the exact bulb for EU5. Back up the mast, it went in smoothly, the keeper went back in place, the light worked. Woo-hoo. Bulb changed.