Canonical links for pages that display data in different units

Much of the content on my site is specifications for various boats. Users in the USA (my primary audience at present) likely want to see these specifications in units of feet, pounds, etc, whereas most of the rest of the world wants to see them in metric. Should these pages have unique canonical links, or should one point to the other?

On one hand, the content is semantically the same, so I feel like they should share a canonical tag, but on the other hand, different users will want to see different versions. A similar problem pops up with languages, which is solved using hreflang, but I haven't been able to find anything similar for this situation.