: The fierce currents, standing waves, inaccessibility for landing craft seem
: to preclude use of boats/barges for repetitive landing of equipment and
: materials. The island is in the Scylla and Caribdis of the east coast.

: As other posters have noted, you can't make concrete from salt water (and
: beach sand)...I think it is the chlorine content.

Must be why the roads in Chicago don't last. we put lots of salt on the concrete roads during the winter, to melt ice, and it eats them up. But fresh water ccan be barged in as well as flown in -- assuming you can get a barge in at all.

: One interesting thing you might appreciate ... helos. can carry heavier loads
: in cold air vs. warm air ... not just theoretical, but practical....the
: helo. with the heaviest capacity is Russian - 2 x 11,000 h.p. gas
: turbines, 240 ft. rotor span, supposedly up to 32 tons in cold air (like
: Siberia?)

Colder air is denser. So is drier air, I believe. Humid air has a lot of water vapor, which, since it rises, must be less dense than air.

: Wish it were my $$'s ... I'd retire and build kayaks instead. Trust me, you
: don't want to know the source of the $$'s.

My taxes?

If anyone has any ideas, they would be greatly appreciated...I even thought
: about floating over concrete docks to be used as a cap, but they are even
: more expensive than the helo!

Move concrete ingredients and a mixer on barge to as close as you can get. Helicopter takes off from barge, so it just a short hop the rest of the way.
Use smaller, cheaper helicopter(s) (say $150 per hour instead of $1000) which can land on the barges, or hover above them, and more, but shorter, trips.

Why use concrete? Not knowing a thing about the hole you have to fill in, mind you, I can think of several other possibilities: 1) Fill the hole with beach sand, 2) lower a stick of dynamite down it about 25 feet and cave it in with an explosion (they do that in the movies a lot) or 3) You could probably get a good deal on buying epoxy in bulk and use that. Be sure to deal with a company that gives free shipping.

Seriously though, sounds like you have a neat challenge, and I wish you well with it. And water conditions in that area sound like challenging kayaking, too.

PGJ