The latest
issue of BoatU.S. magazine insists
that a boat can float on air. Well, I
can only say that no boat I’ve ever owned was able to float on air, although I
can see several advantages straight away.
You wouldn’t need anti-fouling paint for a start, and you wouldn’t have
to keep it in water, which would save you a bundle. And you wouldn’t need a
trailer to tow it anywhere.
But
apparently some boats really do float on air. According to the magazine
article, Michael Peters Yacht Design has produced a powerboat hull with what
they call a Stepped-Vee Ventilated Tunnel.
This tunnel
traps air under the boat and channels it to the stern. This, they claim, reduces
friction, and therefore drag. These
hulls can reach 60 mph with two outboard motors, and average better than 1.5
miles per gallon while “cruising” at 45 mph.
That compares with a top speed of 55 mph for a Boston Whaler 37 (which
doesn’t have a fancy cushion of underhull air) and fuel consumption of about
twice as much. Beneteau also recently introduced a powerboat technology they
call AirStep, which draws air in from the hull sides and blows it out under the
center of the hull.
The BoatU.S. article says: “Addition of air
under the hull at low speeds adds lift to the stern, reducing the displacement
of the boat, which flattens the bow wave. The result is a boat that rises on
plane sooner . . .”
Now I have
always understood that aerated water is less dense than normal water, and
therefore less able to support a floating body. If you’ve ever body-surfed,
you’ll surely agree with me. What’s
more, adding air under a boat cannot possibly reduce its displacement, which is
its weight.
I know we
live in exciting times, when colliding particles are producing Higgs’ Bosons
all over the place and McDonalds is producing vegetable burgers, but it’s
really, really hard to believe that bubbles in the water will lift a boat and
hold it up higher so that its bow wave is flattened.
So far this
principle is not being touted for sailboats, but I don’t doubt the day will
come, probably among America’s Cup racers or the Open 60 class. Between now and then I am going to have to do
some hard thinking, and possibly some rearranging of my scientific
prejudices.
Today’s Thought
True science teaches, above all, to doubt,
and to be ignorant.
— Miguel de
Unamuno, The Tragic Sense of Life.
Tailpiece
“What do you
want to be when you finish college?”“You know, I’ve half a mind to go into politics.”
“Great, then you’ll be better equipped than most of them.”
(Drop by
every Monday, Wednesday, Friday for a new Mainly about Boats column.)
2 comments:
Is this the same as the Hickman Sea Sled? Or derived from it? Also, I think Robb White did something along those lines, too, although I can't remember the name of it.
Have faith. there's science in there somewhere.
Bill, As far as I recall, the Hickman Sea Sled was a catamaran, an early cathedral hull, grandaddy of the Boston Whaler.
Dear old Robb White might have experimented with blowing bubbles under his hull, but I never heard of it. He specialized in "sport" boats that were a combination of rowing boats and canoes, boats that would plane at 11 knots with a 3 hp outboard motor. It's a hoot to Google "Robb White boatbuilder" and look up his website. Wonderfully entertaining writer.
John V.
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