A friend sent me this today:

We are going through NY today and are having an argument maybe you can
resolve.

We imagine two boats one leaves Throgs Neck one hour before the current
change at Throgs. He does 6 kts through the water. Is there a later time
at which another boat can leave WITH the current also doing 6 through
the water where the second boat will arrive at Verrazano Narrows at
exactly the same time?