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?

On Oct 20, 1:38*pm, Jeff wrote:
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?



Often when pushing a fuel flat on the ditch from Galveston/Boliver to
the Sabine river we could time departure up to 6 hours later and
arrive one hour faster. But we have an offshore cut (rollover) half
way that will push and pull you on both sides. The lugger tug
(Cherokee Warrior) had a single 8-71. She could only muster around 4
knots pushing a 220 X 40 fully loaded barge in still water..... so
timing was everything. You would do 8-9 knots with the proper timing
and could almost sit still with the wrong timing.

Now without an center drain/fill point I'd doubt it.

Joe

On Tue, 20 Oct 2009 14:38:53 -0400, Jeff wrote:

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?

No.

The boat that leaves first will always stay ahead because they will be
in stronger ebb current first as they approach Hell Gate, and at no
time will the adverse current exceed their boat speed of 6 kts, so
they will always continue to make forward progress.