I’ve seen in some shows and cartoons subs surfacing at high speed so that their bow breaks the surface at an angle then crashes back down to rst on the surface (here’s an example: VBC USA Navy Submarine Emergency Blow - YouTube)
How steep an angle could they manage? I’ve seen in one anime the vessel coming out near-vertical (for dramatic effect)
Wouldn’t this damage the hull (particularly the keel)? I know subs are built to withstand enormous pressures, but not too sure they could handle the amount of tension this would cause
There is a maximum up angle that a sub can safely achieve, and it’s less than vertical. That’s about all of the detail that anybody who actually knows will be able to give you.
An emergency blow does not cause any damage to the hull (assuming the sub ensures the area is clear and doesn’t run into anything on the surface). (Unfortunately, this was not the case in one infamous instance.) We used to do them quarterly for training purposes and to ensure the equipment was working properly.
The first time I was onboard during an emergency blow, I eagerly anticipated the event and stayed up despite the fact that I had just come off of the midwatch and had been awake for nearly 24 hours. A year later, I actually slept through an emergency blow. The emergency blows were actually far smoother than when we were driving on the surface in heavy seas. There were times on the surface in heavy seas where the hull sounded like it was going to collapse. :eek:
In fact this is how the USS Greenville struck and sunk the Japanese fishing trawler*** Ehime Maru***. The trawler sank and two students were drowned during the collision.
I hadn’t thought about subs being designed to operate on the surface in heavy seas (which would exert the same sort of stresses as a high-speed breach).
I am confused. There are numerous articles referring to the keel-laying ceremonies for new nuclear submarines, like the USS John Warner. Is this just a figure of speech these days?
You know how on TV there will be some people floating around in a rubber dinghy and a submarine will gently come up under them balancing the dinghy on top? Can they really do that?
Um, it could happen, but not like you see it on TV or movies. First of all, the sub’s going to have to come to periscope depth to spot the dinghy and see to maneuver under it. Since 007 is too busy smooching the babe of the film, they never notice that. Step 2 is where reality steps in and ruins stuff.
There’s only 2 ways a sub can surface. There’s probably some jargon the bubbleheads know that I don’t, but they can either surface under propulsion, where the boat has to be going forward and the dive planes are angled upward to drive the boat to the surface. That means the sub needs a sort of head start to the dinghy and if they manage to center the dinghy on the deck, it’s going to smash into the front of the sail. The other way is to maneuver under the dinghy, come to a full stop, and then blow the water out of the ballast tanks. And that’s going to result in a lot of foam around the dinghy.
Thirdly, in WWII era subs, there was a flat slatted wooden deck on top of the pressure hull which would be great for picking up a dinghy that way. If the life lines weren’t rigged. But the subs nowadays are curved. So the chances are a rubber dinghy would slip off the slippery top of the hull and over the side.
I think it’s more a matter of need & comfort vs. engineering. IOW the subs are probably capable of (nearly) vertical emergency ascents, but it would be hugely inconvenient (not to mention dangerous) for the crewmen and equipment inside. Plus, there would be no real advantage or need to ever do so…
Was randomly surfing Wikipedia for facts on US submarines in WW2, and came across this relevant bit on the USS Chopper:
[QUOTE=Wikipedia]
The crew’s efforts began to take effect. Chopper lost the headway that was taking her deeper, and even began to make sternway. Her bow began to rise, reached level, and continued to climb. Chopper began to ascend with a rapidly increasing up-angle until she was again nearly vertical in the water, now bow up.
About two minutes after losing electrical power, Chopper shot through the surface of the ocean, nearly vertical. The entire forward section of the submarine, to the aft edge of the sail, cleared the surface before she fell back. Her momentum carried her down to a depth of about 200 ft (61 m) before she surfaced again, leveled out, and remained on the surface.
Chopper returned to port under her own power. Inspection discovered that her hull had suffered extensive structural damage during the deep dive and rapid ascent. Chopper was decommissioned on 15 September 1969.
[/QUOTE]
So yeah, it can be done, with extensive but not crippling damage.
WW2 era ones certainly did, given they were surface ships that could occasionally submerge. See, for example, Norman Friedman’s treatise on submarine construction prior to 1945. (It’s searchable on Google Books. ). I do not know if the Albacore and its successors did or not: I.e. when the USN went to the modular cylindrical construction they evidently use now.
The thread we recently had on whether a nuclear submarine could operate upside down, would probably be of interest. As robby said here though, anyone who really knows ain’t talking.
First off, a sub can drive to the surface (as you say), but it won’t stay surfaced unless the main ballast tanks (MBTs) are emptied of sea water. This is can be done in two ways: either blow the water out with high pressure air, or use the low pressure blower to slowly empty out the ballast tanks. The latter method takes about 30 minutes, and is the usual method of surfacing. To use the LP blower, the sub has to be at periscope depth (PD) or shallower, and the induction mast needs to be raised to supply air from the surface. To get to PD, the sub first drives to the surface using propulsion and the planes.
In an emergency, the sub uses high pressure air from the emergency blow system to quickly empty (or partially empty when deeper) the MBTs. This operation is what is being done in the OP’s video.
Some classes of sub also have a “normal blow” system, which is a separate bank of high pressure air and piping which can be used to evacuate the MBTs of seawater. Some classes of subs designed for under-ice operations have a similar system used to slowly use high-pressure air to evacuate the MBTs when surfacing through ice.
The top of the hull of a submarine is not slippery. There is a section of non-skid at the top of the hull so that crewmembers don’t slip off when walking around topside when in port, or during underway operations when leaving or returning to port.
