Good point! I should have mentioned that. It was rather a strange feeling to be traveling in water like a motor boat in a 46. We did that more than once while offloading Green Berets and Montyards into rivers in places were we never went while under the cover of the over hanging trees. We'd turn around in the river and motorboat back to where the overhanging trees weren't prevalent, and take off to fly back to our refuel point. Then after a few days we'd return to that same river where we never went and motorboat along with a long knotted line hung out the back. The troops we had dropped off days before would grab the line and pull themselves back into the cabin. If they missed the line on the way in, they hoped to catch it on the the return trip out.
Having said that, your comment about seals and drain plugs was spot on. Every 46 I made a water landing or cruise in did tend to seep water. I'd not want to have to spend much time in the water without the rotors turning!
On another topic. I just checked out and read a library book called FLIGHT 100 YEARS OF AVIATION. This book probably weighs 10 pounds or so and goes back to early balloons. They even found one (1) page to mention "HELICOPTERS IN VIETNAM." That single pages lists seven(7) different choppers. The H-46 was not even listed there or in the index. They mentioned and had pictures of the H-34, OH-6A, H-47, etc. But the H-46 didn't make the cut. They had pages and pages about hot air balloons etc. but only one page on Vietnam choppers from all our armed forces.