In a large pot over high heat, combine the beans with water to cover and bring to a boil for 10 minutes. Remove from heat, but let sit for 1 hour.

Drain beans and place them in a slow cooker. (If using ham hocks, add now.)

Add the onion, brown sugar, maple syrup, salt and water.

Mix well, cover and cook on high setting for 4-5 hours, stirring occasionally.

During the final hour of cooking, add the ketchup and mustard (if you used ham hocks, remove the ham from the hocks and discard the hocks.).

Mix well and serve.