|John Smith demonstating his compass|
The most popular known sundial compass today is called the "equinoctial" compass, and was first brought to use around 1630. It looks like a pocket watch with a compass at its base while a folding lid containing the Gnomon ( the blade ) and the clock dial lays atop. This is a standard compass that can be used anywhere within the latitude range of Canada to Mexico. Although, if an explorer was to travel more southernly or northernly they would need to make some adjustment to the angle of the blade before they'd get an accurate time reading. Even in the standard range, adjustment has to be figured depending on the time zone you are in. Otherwise your "clock" can be off by a few minutes to more than an half hour.
On second thought, maybe just carrying a pocket watch and a compass would be a smarter choice for the modern mariner.