Multiple uses of the same volume on a boat is the ideal.  A double sink dedicates that volume to a single use.   If you use a plastic wash tub beside a single sink, the tub can be moved away when not washing and you get to use that volume for something else.

Jay,

Yeah, we find that the big, single bowl works really well for us. If we're strapped for water, we fill a washing tub with salt water for washing, then rinse with fresh in the main sink bowl. The little bowl in the back works great for keeping knifes, silverware, etc, or keeping a few cups of coffee when heeled.


~A