Can I use yacht varnish on a brand new eucalyptus wood garden table?

Marine varnish should be fine

marine varnish would definitely help against the elements outside.

Good Evening Kathleen :) According to everything I have read eucalyptus wood really doesn't need to be painted or varnished to protect it, and is actually adivsed AGAINST doing so, because the natural oils in it will react against the pint and the varnish. what IS recommended is using an application of oils to help deepen the color so it remains looking like new but not so much to 'protect' it as it is such a dense wood with its own natural oils. I would recomment doing what the link below says, just to be on the safe side and prevent any sort of cracking or peeling in the wood down the line ;)

When you initially wipe it down with acetone use a paper towels, using ONE towel per swipe and going in the same direction each time to keep from smearing around the wood's natural oils, and once you see the acetone has dried lean down close and look for little puddles of more wood oil and wipe it down once more time the same way one swipe per towel. The linseed oil should be 2 pasrts linseed oil and one part mineral oil (to help carry the linseed oil down into the wood fibers, otherwise the linseed oil will remain on top and eventually get a tacky feel to it, and no one wants to sit at a tacky feeling table).

http://homeguides.sfgate.com/recommended-finish-eucalyptus-wood-99594.html

Good Luck, and thanks for asking Hometalk for solutions and help. :)

Eucalyptus is not that common, good job on that. KattywhampusLOL's answer is what I would have provided too. Can you post a photo? We would love to see it.

Varathane or marine varnish will do the trick.