Simple (Hopefully) Excel Question

[Maritime Q-Scout]

I'm graphic the tidal shift over a period of several hours. I've graphed it out, which is easy enough.

However, I want to put in a vertical line to specify one exact moment.

How in God's name do I graph a vertical line? Google is absolutely ZERO help what so ever.

[Bend it like Bourgeois]

http://www.mrexcel.com/forum/showthread.php?t=227154

that forum kicks ass for excel questions if thats not quite what you meant.

http://www.bing.com/search?q=site%3A...+vertical+line

[Old Yeller]

Can't you just add another column with the same repeating value?

[RatherDashing]

Can you just use clipart and draw a vertical line on the graph?

[Nage Waza]

This is beyond easy, so keep trying.