I’m reading about the USS Nautilus. For traveling under the ice, reverse fathomometers were installed during a refit. Are there covered openings in the pressure hull for installing new equipment, or are they cut as needed?
You don’t necessarily need to make a cut in the pressure hull to install new sensory equipment. This type of equipment could simply be installed in the sail (formerly known as the conning tower), which is outside the pressure hull, with the cabling fed through an existing conduit penetration in the hull. There are also other portions of the sub (other than the sail) that are outside the pressure hull, but inside the exterior “skin” of the sub.
For what it’s worth, the USS *Nautilus * was a pre-SUBSAFE vessel, and so had a great many hull penetrations. Submarines designed and certified under the SUBSAFE program have vastly fewer hull penetrations.
Thanks.
Something I’ve always been curious about: What’s in the sail? Obviously the periscope and other retractible masts, but what’s in it? I presume a couple of decks, and a ladder (or ladders) leading up to the top, right? What’s on those decks, presuming they exist? Since it’s not in the pressure hull, how does it not collapse? Is it built to withstand the pressure differential? Or is some or all of it flooded? I’ve never been on a sub, and haven’t tried to find a cutaway view.
I’ve toured the USS Razorback, a WWII guppy conversion in North Little Rock. The sail is open to the sea. As I recall not much besides a ladder, a window forward and a shelf to stand on.
How do you seal an opening with a cable passing through the pressure hull?
The Razorback has a replica nuclear torpedo in the stern torpedo room. If the balloon went up, they were to fire it at the ships they had been shadowing, and run like hell.
I don’t know exactly how this is done on a submarine, but the general concept of sealing cables that pass through a pressure vessel wall was solved a long time ago. Here’s a diagram of a strain relief that grips the cable to prevent it from moving in/out of the hole, and also provides a watertight seal by compressing a rubber seal around the cable. A submarine at a depth of 1000 feet has to deal with about 450 psi of pressure differential, which isn’t too difficult; for a 1/4" diameter cable, that’s only about 22 pounds of force trying to squirt it into the hull.
I don’t know how subs do it. But in other systems I had seen passing signals though a wall they have a plate with the conductors molded into insulating material that is integrated into the plate so there are connectors on either side of the plate. So the cable doesn’t really go through the hull but some conductors do and cables are connected to either side of the plate.
I’d rather ride on that boat rather than the one above. That is too much like the bulkheads on aquariums, and it would be made by the low bidder.
This is the way it is done for high vacuum and high pressure also. There is a round disc of ceramic with several solid posts coming through. The ceramic is fired and everything is melted together. A spark plug is a simple example.
Dennis
Pretty much the same as you seal a penetration in a building firewall or fire barrier. Except that submarines have more pressure on their hulls, and more often.
Buildings, especially public ones, have such walls to prevent (really, just slow down) the spread of a fire. (Gypsum drywall used in typical homes, for example, is a minimal level of fire barrier.) These are often penetrated by electrical & plumbing piping. These openings are then closed off with firestops (for example, cement mortar) to maintain the fire resistance. These are often opened to add additional electrical or communication lines, and are supposed to be restored to the same level of fire resistance afterward. Many fires cause increased damage because this was not done properly.
Exactly, the sail floods when the submarine submerges. When the submarine surfaces, seawater drains out from grated openings at the base.
The sail provides a place for all of the periscopes, masts, and antennas to retract into. It also provides an elevated perch for the Officer of the Deck (OOD) and lookout(s) when the submarine is operating on the surface. When a submarine is traveling at high speed on the surface, especially in heavy seas, the forward portion of the submarine is completely awash, as is most of the deck aft of the sail.
Besides the closed-off housing for a bunch of masts and antennas, there’s a vertical ladder inside the sail extending from the deck below inside the sub, through two hatches in the pressure hull, up to a “cockpit” to stand in at the top of the sail. That’s about it.
On a modern sub of course there’s also the fairwater planes and all the machinery to move them. Which was not a feature of the Guppy classes.
Which raises another question: They could be actuated either with hydraulics down inside the pressure hull moving large pushrods that penetrate the pressure hull. Or by hydraulics where the hydraulic actuators are outside the pressure hull up in the sail and the fluid supply and fluid return both penetrate the pressure hull. I can see plusses and minuses to either arrangement. Or are they actuated electrically which would enable using a hefty form of the flat-plate-with-Siamese-connectors approach?
What’s typically done?
Nor is it a feature of most modern U.S. submarines.
The use of bow planes (up forward on the bow of the sub) in lieu of fairwater planes on the sail have been a feature of U.S. attack submarine design starting with the introduction of the improved Los Angeles-class (688i) submarines. These subs were designed in the early 1980s, and first laid down starting in 1985. All subsequent classes of U.S. attack submarines have also had bow planes (Seawolf- and Virginia-classes).
The older Ohio-class ballastic missile subs do have fairwater planes, as does reportedly the Ohio-class replacement, currently under design.
I’m sure that fairwater planes are hydraulically actuated, but don’t know if it is done remotely or not.
The planes of which you speak: pix? Or verbal answer to…huh?
Or bow planes I can picture correctly, and the “fairwater” means, besides being on the sail, they are named that for what reason or function?
Here’s a model of a Virginia-class submarine with bow planes. The bow planes are retractable, as can be seen in this great photo of a Virginia-class sub.
Here’s some photos of fairwater planes. This term for sail-mounted diving planes is apparently exclusive to U.S. Navy submarines. I’m not sure what the etymology of the name is, but think it may be an alternative name for the sail itself. That said, as far as U.S. submarines are concerned, the term is only used as a descriptive modifier in the term “fairwater planes.”
Wow, robby. Thank you.
I grew up reading everything on the WWII & early nuke boats. Most of which had the “modern” fairwater planes not the WWII “primitive” bow planes. As between airplanes & subs I ended up choosing airplanes and sorta lost touch with subs in the late 70s.
Somehow, despite reading about newer subs in wiki & such, I’d missed that the planes had moved back to the bow after the original Los Angeles class. Although now that I try to recall pictures I’ve seen of Seawolf or Virginias, you’re obviously right; no fairwaters. Plus of course your linked pix.
:smack: They’re kinda big; and on the part of the sub that’s most obvious in photos. You’d think I’d have picked up on them disappearing again. :smack:
Subs; they’re always hiding a surprise somewhere. Sneaky things they are.
The Silent Service.
“Fairwater” is actually the sail’s formal name, but nobody uses it in real life.
More generally, a fairwater is something that smooths or streamlines the flow of water on a vessel - as indeed the sail does.
The analogous term for an aircraft would be a fairing.