Great link! The article also references the Savoia-Marchetti flying boats that air commander Italo Balbo flew to Chicago, in 1933. My Dad saw these planes as they flew over Boston (he was on the roof of my grandfather’s house in Dorchester, MA)
As well as being longer, turboprops are a lot lighter than a radial engine so they need to be positioned forward on conversions to preserve the aircraft’s centre of gravity.
Compare the original ag cat with a turbine conversion.
Edit: I’m not sure if the actual engine mount is further forward or if the lighter weight combined with their elongated shape allows the rear of the engine to be in the same position as the radial.
People tend to think of a flying boat as being able to land on 70% of the worlds surface but it doesn’t work like that.
Now, you’ll have to forgive me for attempting to quote a magazine I read 15 years ago. 
The article I was thinking of was an interview with a P5M Marlin pilot. He said 'The thing that killed the seaplane was the inability to land on ocean swells. ’ (Paraphrased) To land on the open ocean one had to match the speed of the waves, which would be below stalling speed. Landing badly could break the back (or keel?) of the plane. Therefore the planes could only land on sheltered waters, limiting them to certain areas, many of which now have airfields.
So along with the other reasons already posted, thats why we don’t travel in large seaplanes any more.
Of course, being testosterone-fueled armed forces types, they had a method for landing in emergency rescue situations. I think they reversed prop pitch and stalled onto the water or something absolutely ridiculous like that?
Another site I found said that they sometimes made offshore landings to evacuate critically ill mariners.
Ok. You got me intrigued.
A quick google gave me images of most of them but I didn’t find a 7 engined plane.
In the late-60s, a B-52 was used to test the new engine being developed for the 747 (and possibly the one for the C-5, as well). A regular B-52 has eight engines in four pods of two. They took off one of the inboard pods and mounted the test engine there.
I found at least one experiment with a B-17 that added an engine in the nose, along with the four on the wings. There may be other 5-engined planes.
Good article. I hadn’t realized what a techno-mess that thing was. 1,650 ft is pretty sad.
Yes..in fact, the Trans-Atlantic crossing (West Africa-Rio de Janeiro) was so dangerous (headwinds would have slowed them to a crawl), that the pilot delayed the passage by several days. The fuel consumption at 1600 ft. must have been enormous.
A flying boat in a literal sense. Not so much an airplane that could land on water, but a boat that could (barely) fly.
The Russians must have been impressed enough by the idea. I give you the Caspian Sea Monster ground effect vehicle. Earlier version.
You didn’t need ocean waves to do that, either. Captain Merz of the Do X snapped her tail off in the River Danube by putting her down a little nose-high. And he had more hours in that plane than anyone.
Do h
I think you mean “Do’h!” :smack:
Trapeze act? 
This video showed up in the inbox today. It’s about the Pan-Am Pacific Clipper getting home at the start of WWII
Holy crap. What a story. If anything deserves a documentary that does. Excellent link.