Put a submerged cabled drone just below the surface, with a flying drone just above the surface, right over it. With only a few meters of water between the two, communications between them should be easy. But with nothing actually breaking the surface, you won’t produce a wake. Design the flying drone to not be invisible to radar, but to look exactly like an albatross (which should be plausible, at submarine speeds).
I think that there’s far more possibilities with respect to submerged communication than the Navy is admitting to. If there wasn’t, and a submarine was cruising under the ice cap, how would it ever get a message to launch it’s payload?
I know the crew members get emails from home on a regular basis. If that’s possible, then communication is probably not a big problem.
Is this really “periscope depth”? Looks like there’s more than just a periscope above the water.
We were operating with a P-3 one day - had both scopes and an antenna raised, and still had to vector him in and mark on top several times before he finally found us. I don’t recall the sea state as being particularly noticeable at the time.
A periscope and two antennas. The top of the sail is definitely submerged.
For those who’ve never seen it: https://www.youtube.com/watch?v=eOqalX5FJ2c
See post #20.
Not that regularly (depends on what the boat is doing), and requires an antenna out of the water. Definitely an improvement on the old familygram system, where a wife was permitted to send six 50-word messages to the boat during the course of a deployment. Note that the allotted fifty words included his nam at the beginning, and her name at the end…
You could also grow up"…deep in the island archipelagos on the Andaman Sea, and along the west coast of Thailand [among] small tribes called the Moken people, also known as sea-nomads," who, underwater at least, hyper fold their lenses “naturally” to accommodate, that is, adjust the refraction.
And it can be learned. Cite: The ‘sea-nomad’ children who see like dolphins
BBC: March 1, 2016.
SerenDipity.
Thanks for that. I’ve never really wondered why you could see some things in the water, and sometimes not. But never thought to investigate the basic scientific reason.
The world is ever-interesting.
That’s a solution to a different problem. If both you and the thing you want to see are underwater, you’ll have line of sight to it, but you’ll have a hard time focusing. The trick the Moken people use (whatever it is; that’s not a very clear description) will help with that, as will just wearing goggles. However, if you’re above the water and trying to see something below the surface, the troublesome refraction is occurring at the water’s surface, not at your eyes, and nothing you do at your eyes will help, because no light from your target can reach there at all.
Polarized lenses.
Again, no. Polarized lenses help reduce glare from the sun off the water, which overwhelms the light from the thing you’re trying to see. But the critical angle means that no light from the thing under water is reaching you at all, so there are no tricks you can do to see it.
Look at the diagram on the wiki page. As the angle decreases, more of the light is reflected back into the water, and never reaches an observer.
The part that seems odd to me is that they didn’t know there was a private yacht nearby before surfacing. I thought keeping track of surface traffic was like, submarining 101, no?
See Ehime Maru (also mentioned upthread), which was sunk after being struck by a sub conducting an emergency blow demonstration without first adequately surveying the surface for nearby vessels. Yes, keeping track of surface traffic is Subs 101, but sometimes it doesn’t happen to the extent that it’s supposed to.
They weren’t surfacing; instead, they were just going to periscope depth (PD). (If they had actually surfaced, the people on the yacht would certainly have been aware of their presence.)
Note that submarines routinely go to PD for a variety of reasons, including communications. Per this Naval Postgraduate School master’s thesis abstract (which is approved for public release), “Submarines…have specific communication and time requirements they have to meet and the primary method of transmitting and receiving data is via satellite, which requires the submarine to be at periscope depth.”
And yes, when you go to PD (or surface), it is indeed critical that surface traffic be monitored.
Per this DoD article: “Navy submarines most commonly use ‘passive sonar,’…described as ‘listening devices’ that detect sound released by objects in the ocean.” Also from the article: “[T]he Navy primarily uses passive sonar, because it doesn’t give away the position of the ship.”
So if you have a vessel on the surface that is not making any noise, like a small yacht or sailboat whose engine is shut down and is just drifting with the current, it can be difficult to detect them with passive sonar. Instead, the contact might only be detected by visual means (using the periscope) as the sub ascends. So it is theoretically possible for a submarine to find itself closer than it would like to a silent contact. This usually doesn’t happen, though, for the simple reason that the ocean is large and vessels are small.
In any event, implicit in the sea story/urban legend is that the submarine was aware of the yacht or sailboat in question (either during or after getting to PD), and that they pruriently spied on them via periscope. Personally, I think it’s a bunch of BS.
For what it’s worth, your posts on these subjects are always appreciated. It did not occur to me that passive sonar would not necessarily pick up a boat that wasn’t under power, but that makes perfect sense.
Can a submarine maintain periscope depth while stationary? AFAIK, the ballasting is not precise enough and a bit of input from elevators is needed.
It is rarely desired for any vessel to be stationary at sea. If you are stationary, you are said to have lost steerage way, and the vessel does not respond to the rudder or other control surfaces. In other words, you have no maneuverability. For this reason alone, you would not want to depend solely on changes in ballasting to go to PD, especially when you take wave action into consideration (which adds some unpredictability into the equation).
With that said, I have been aboard a submarine that surfaced up through the polar icecap. We were stationary (i.e. vertical motion only) during this evolution, which was accomplished solely by controlled deballasting. However, note that there were no sea or wave conditions to deal with.
Yes but surfacing is easy - you just blow out and the boat has no choice but being buoyant. It’s my understanding however that maintaining a specific depth is not just a question of ballast but also constant control via the ailerons, which implies at least token forward movement so the control surfaces work, as you say.
For the record, the control surfaces on a submarine are referred to as [dive] planes or hydroplanes, not elevators and certainly not ailerons. 
Submarines have stern planes (near the rudder), and either bow planes (up forward) or fairwater planes (on the sail).
I stand corrected. :smack: