How many doubloons is a dollar?

I'm curious, how would one go about converting a dollar into doubloons? Is there a fixed exchange rate, or does it fluctuate depending on market conditions? And what factors influence the value of a doubloon in relation to a dollar? Additionally, are there any historical precedents for the exchange of these two currencies that could provide some insight into the current situation? It seems like a fascinating topic, and I'm eager to learn more about it.