I would like to know what is the largest operational (flying) float
plane in the world.  I flew on a 1943 DC-3 float plane late this
summer and can testify that it did indeed leave the ground (water). 
There were claims made that it was in fact the largest, but I need to
be sure before passing the claim on myself (journalistic reasons). 
Please note the distinction between float plane and sea plane; a sea
plane (or flying boat) has its hull and fuselage integrated, whereas a
float plane is more like a conventional plane converted by adding two
hulls below the fuselage.  I'm sure there are larger seaplanes, it's
the largest float plane I'm after.  I'm a return customer, I was very
impressed with this service the first time.

hi bobh33,

The largest float plane ever built is the HK-1 (Hughes/Kaiser), later
changed to H-4. The Hughes Flying Boat is commonly called the "Spruce
Goose" - It has the largest wing span (320ft) of any aircraft ever
built. The Spruce Goose only flew once in 1947. Today it can be found
at the Evergreen Aviation Museum.
Official "Spruce Goose" web pages:
http://www.sprucegoose.org/

Today, the largest flying float plane in operation is the "Martin
Mars", and it's the worlds largest water bomber, with a length of 120
feet, a wing span of 200 feet and a drop capacity of one million
liters (265,000 U.S. Gallons) of water during a single sortie (37
consecutive drops 5.9 hrs). Sproat Lake is home of the Martin Mars.
There are two Martin Mars still in operation - the Martin JRM-1
"Philippine" Mars, and the Martin JRM-1 "Hawaii" Mars .

Bush Pilot John Lovelace has spent the past four years covering every
corner of Wilderness Canada and documenting his discoveries in the
WINGS OVER CANADA TV series. The series, now seen weekly just about
everywhere in North America, is a lighthearted look at Canada, its
people, history and customs. In "Flying Series" No. 4 John Lovelace
looks at at the Flying boats both small and large still operating in
Canada . According to John the Martin Mars is "second only in size to
Howard Hughes "Spruce Goose". But this huge airplane still flies!"
Wings Over Canada series website:
http://www.wingsovercanada.bc.ca/

The Martin Mars is the largest float plane "ever flown operationally,"
say its owners (Forest Industries Flying Tankers Ltd. of Port Alberni,
B.C.)
Source: "World's biggest water bomber awes Atlin" by Jonathan Morse,
News reporter, ATLIN, B.C.
http://www.yukonweb.com/community/yukon-news/1998/july15.htmld/

------------------------------------------------------------------------------------------------
related sites:
"Wings over the Pacific"- image based, aircraft information website
http://www.pacificthunder.com/wings/martin.htm

The Martin Mars Flying Boat Personal WebSite
http://www.vectorsite.net/avmars.html 


The Martin Mars Flying Boat Personal WebSite
http://www.jimmyhoward.com/Martin-Mars-history.shtml


MARS Flying Tankers Personal WebSite
http://www.martinmars.com/
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search terms used
"largest float plane" world +
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Request for Answer Clarification by bobh33-ga on 27 Oct 2002 09:52 PST

Please refer to the question; particularly the distinction between
float plane and flying boat.  As far as I can tell, all of the results
you have returned concern flying boats and none refer to float planes.
 There is a big difference, even though many people use the terms
interchangeably.

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Clarification of Answer by jackburton-ga on 29 Oct 2002 05:36 PST

Yes, it would seem that the term "float plane" is also used to
describe "flying boats".

It does appear the DC-3 is indeed the largest float plane in the
world, (i.e. modified with hulls beneath), though I have been uable to
find an official source that confirms this.  The DC-3 was converted to
a float plane by Dick Folsom in 1976. The experimental type
certificate for this aircraft was awarded in September 1990 and the
first flight took place at Greenville airport at that time. It is said
that it is the only DC-3 on floats flying today.

I have found the following references that confirm that the DC-3 is
the largest float plane:
"...Greenville is one of the largest sea plane bases in New England,
and is home to the largest float plane in the world, a DC-3."
http://www.greenvilleinn.com/grnvill4.html

"....That one (DC-3) is registered as a plane, not as a boat. "World's
Largest Float Plane" they call it. Only things bigger are flying
boats, using the hull for floatation like the PBYs or the Spruce
Goose...."
http://groups.google.com/groups?q=%22I+assume+you+aren%27t+talking+about+the+DC-3%22&hl=en&lr=&ie=UTF-8&selm=7ol36e%24bna%241%40nnrp1.deja.com&rnum=1

related links:
the Greenville Maine International Seaplane Fly-In
http://www.seaplanefly-in.org/

Facts & photos about the DC-3
http://www.douglasdc3.com/prev/prev.htm

You may also like to contact the Greenville Seaplane Base (tel:
207-695-2993).