hval
Sea planes always fascinated me as a child.
I found them fascinating too, though I'm not sure for the same reason: For an airliner they could be so much bigger as a 10,000 foot takeoff run wouldn't be a concern, and night-vision could allow you to gauge the height of the swells, which would even make nighttime operation safe.
The Seamaster was intended to deliver nuclear store. Polaris systems were used instead.
Correct, it could also deliver conventional ordinance including bombs, and even mines.
They were intended to provide additional power on take off.
That would give the plane a pretty good T/W ratio -- I'm surprised you'd need such a high T/W ratio to get a sea-plane out of the water.
Kitbag
Although not supersonic it was required to achieve M0.9 at low level, this, combined with a max t/o weight of about 160000lbs may go some way to explaining it.
It needed burner to hold subsonic speed at sea-level? I thought it would be able to fly dry down-low....
Regardless, just the fact that it weighed less than a B47, could carry a greater load at a higher speed up high and down-low, was sturdier (I don't know what it's maximum g-load was, but that aircraft was built like a tank), had a greater thrust to weight ratio and a lighter wing-loading all sound like awesome advantages, though truthfully I don't know if it could fly as far.
Turbojets were still pretty gutless in the early '50's - the original design was going to use turbo-ramjets
Why would they need turbo-ramjets? How fast were they originally planning to design this aircraft to fly? Are you confusing this design with a Mach 4 design Convair proposed -- a turbo-ramjet makes more sense for that design than a high subsonic aircraft...
As far as I know, the production series had non afterburning J75s that were rated at about 17000lbs.
Considering the thrust figures of jet-engines almost always seems to be under-rated (either a fudge-factor is incorporated, or the thrust figures are based on conditions other than sea-level thrust) -- as I understand it J75's had thrust levels as low as 15,800 (as used on the B707-220), with most around 18,000 - 22,000 lbf dry (this is consistent with the statements that the J75 was 50% more powerful than the J57).
jamesdevice
Shame we don't have fleet of these.
Seaplane aircraft have a fundamental advantage in the fact that more of the Earth's surface area is covered by water than by land. The only thing that could be better would be an amphibious aircraft.
The only drawback that the P6M had would be that it wasn't really designed to reliably land at night as the height of the swells could not be reliably gauged. Though as far as I know the plane could refuel in mid-air, so as long as there wasn't an imminent problem, they could just keep refuelling until the sun comes up, then land.