This quick tip has come in handy for me several times on my boat. I have learned to keep an empty line spoon and even a spare empty reel (usually one not up to snuff anymore for fishing) on my boat.
Ever have a reel give up the ghost on you with 10 colors out and no way to reel it in? If you have a line spool or a spare reel you can at least salvage your line until you can replace your bad reel. If you just hand line it in and put it in a pile you will likely just end up throwing everything out.
Have a nasty tangle with a lot of line still out. Use that empty spool to hand line your line in until you can get things under control.
One thing to remember with a spool vs. a reel, roll the line on to the spool vs. wrapping. This is a pain but if you wrap the line, you will create all sorts of twist in your line.
Anyway, I hope you find this quick tip helpful. It has saved me a lot of grief several times now.