There is not currently an option for this, no. It may be a little counter intuitive to have a navigation that is open and 'infront' of the actual content on a site on first load as this is likely to confuse the users.

If you really need this type of functionality then there should be some custom javascript you could write - a good starting point would be to check out the documentation here -http://foundation.zurb.com/docs/components/offcanvas.html... under 'Programmatic show / hide / toggle' near the bottom of the page. Not something we could help with I am afraid.

BTW - there is also an other navigation option which is very similar to our Fundamental theme -http://fundamental.57.formigo.co.uk/.... You do not have to use the 'Off Canvas' style navigation in other words ;)