There are a couple of ways to remove water marks from wood. White toothpaste seems to have the best results. Simply rub it on with a cloth for a few minutes until you see results. See the full instructions and other methods here.
I would use a more natural jute rope you can usually find at your local dollar store :) check out The Metal Barn to see what awesome rustic finds we\'re making in the barn! Rope covered coffee cans, jars, etc. nice to give something in