How does the law work when getting a divorce when things such as boat and four wheelers that only has one name on it? Can one now claim inheretance?

Inheretance ? Who died, your family member or your soon to be X's family.

What state is this located at ( if US)

If you are divorced from your spouse, you are no longer in a position to claim an inheritance if he/she dies. If there is a will and you are specifically left something by the divorced spouse, well then, lucky you. If you aren't divorced yet and are interested in sole possession of these material things you have mentioned, the titles need to be changed into your name if the soon to be ex is willing to do so, or the items can be sold and the money split between the two of you as part of the marital assets.