作者： Morgane

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Silent Service: Principles of Submarine Design (1)

by Morgane 2017年9月17日

Tautog here. I’ve been reading the comments and the mail and I’ve just realized that we haven’t talked about the very basics behind submarine design yet!

(Also, I’m a little tired of people arguing over which submarines are the best. The answer is of course the AMERICAN one, but you can make a good argument for many other countries’ creations, too!)

We’ve talked about the necessity of maintaining buoyancy before. However, I think it’d be good to just list off some general constraints that submarine designers are working under. So, in order, we’re going to be talking about the pressure hull, the materials of construction, the conning tower and periscope, and the powerplant. I’m also going to use the American ones during WW2 as an example – if you’re interested in the submarines of the other countries, I can grab one of our other girls to answer instead!

Since this is somewhat long, today we’re just going to talk about the hull of the submarine itself.

Okay. So. Pressure hull. This is the submarine itself. If you think about it, the submarine is literally just a giant metal floating box that needs to sink on demand, right? The pressure hull is the “wrapper” around all the machinery that goes into a submarine. Generally speaking, submarines are volume critical and not weight critical. This is because the submarine is completely enclosed, so any attempts to save weight will not necessarily result in smaller displacement, because the volume of the materials don’t change.

What this means is that weight saving measures can then translate into thicker pressure hulls. A thicker hull means that you can dive deeper. While it’s tempting to think that it would be good to make a submarine with a super-thick hull, eventually you hit a point where most of the weight comes from the hull itself. We call this being “weight critical.”

(If you have very heavy batteries or machinery, it might cause the same thing. Remember! You want to distribute the weight in a generally even way.)

This is not good, because it means special precautions must be carried out to make sure your submarine don’t sink like a rock. This issue is typically solved in modern submarines via a combination of very light but sturdy materials or careful placement of their inner machinery. Pre-WW2 US steel, by the way, was rated at a dive depth of about 250 feet. Today submarines obviously go a lot deeper than that!

Speaking of the hull, the shape of the submarine matters, too. In theory, a completely spherical object would be the best at resisting pressure. You actually see this principle at work in deep sea science exploration probes. However, a spherical submarine wouldn’t have very efficient use of space. As such, most submarines are in those long cylinders that you are familiar with today.

The important thing about cylinders isn’t that they’re cylinders, though, but rather, just what sort of a shape it is in. Generally, the designer have to keep in mind the overall surface to volume ratio, since higher surface area naturally causes more drag, which makes the submarine less agile. However, longer submarines could also fit in more powerful machinery. So in cases like the modern day Los Angeles class submarines, it actually worked out to be positive overall.

Anyways. Generally, there are three types of submarine hulls during WW2 times.

  • Single hull: All of the tankage (the ballast tank; what controls the buoyancy of the submarine) is found in one single “shell.” It’s easier to build this type of submarine, and it has the least amount of surface area, so it is stealthy and fast. The downside is that with the tankage being inside the sub, you have a lot less space to fit in machinery. The US started out building single hull submarines, then went away from it quickly enough. It isn’t until modern day nuclear subs that we see the single hull submarine come back again.
  • Double hulls: It’s as the name suggests. A floodable second hull encases the pressure hull, and reserve buoyancy is provided in the tanks located between the pressure hull and the case. The advantage here was that the submarines were bigger, they ran more efficiently on the surface (because of their larger freeboard, which improved seaworthiness), and they generally have greater range (owning again, to their greater size). Some think that the extra layer of “armor” makes it tougher against the lightweight submarine-killing torpedoes, but others don’t think so. In either case, the downside was that the double hull was technically challenging to build, and it dove very, very slowly. While it was pretty commonly used by many European countries around WW1 and inter-war eras (including the Surcouf, teehee), today only the Soviets (Russians) really stick to the double hull design.
  • Then we have the compromise, or what is called the saddle tank design. Here, you have tanks mounted externally on a single hull submarine. This allows for much better compartmentalization and habitability since you’re carrying all that water outside, and the extra tanks actually allowed for a measure of stability due to the greater contact area between the submarine and the water. The downside? It had significant underwater drag, and it dove somewhat slowly as well.

So, yeah. I’ll probably go over some notable submarine examples in the next piece. In any case, I feel like it’s just something people should know about. Submarines are pretty neat, after all!

See ya next time.

前线来信·Mail call, 美舰本·Pacific

[Mail Call] 9/15/2017 – Everyone’s Busy Edition

by Morgane 2017年9月16日

Long day. Pretty busy week catching up on work IRL and of course, here.

Days like these where I don’t have an update on top of what I do regularly for Pacific I go dig for random sketches in my folder.

I don’t have a spare catapult anyways to remodel Saratoga. And, with how fast November draws these days (he’s really, really busy), we might just have to start posting the girls directly online instead.

Yeah… It’s long weeks like these where I kind of feel bad about some wildly ambitious goals and timetables I set for myself. There are some days you come home and you literally don’t want to do anything but sleep. Sometimes I wonder what’ll happen if I can actually spend all my time on this, but then again, it wouldn’t be the same. Pacific’s the way it is because it’s a hobby first, after all. 🙂

But, hey. One day at a time. One bit at a time.

前线来信·Mail call, 美舰本·Pacific

Silent Service: Submarine Special Operations

by Morgane 2017年9月15日

Hi! Tautog here. Today we’re going to be talking about submarine special operations during World War II.

When we say the word “special operations,” many people have this mental image of um, super well trained masked men dropping from the skies. Super secret missions! Top-of-the-line gear! Operators! Pew pew blam, America!

That sort of thing is definitely a sort of special operation, but it is by no means the only operation of its type. In short, a “special operation” is exactly what it says. I would define it as a particular mission that requires unusual, unorthodox, or specialized individuals to accomplish. In that sense, then, the submarine was a prime candidate for these sort of things. A submarine’s ability to penetrate a hostile area without being detected, and the fact that it can stay for a long time without replenishing itself would become a big tactical advantage for the U.S.

I am, of course, talking about scouting. Many submarines had these as explicit goals as a part of their war patrols. Go in, check out what units the enemy has on the surface and near the shores, and report back. Remember we talked earlier about submarine communications. Many of these subs are equipped well for relaying information back to base. In this way they allowed the Army and the Marine Corps to make very informed decisions and largely minimized the unnecessary risks we would have taken.

But the submarine force did a lot more than scouting. The submarine force delivered supplies and men to guerrillas and special agents operating behind enemy lines. That’s the literal “special forces” per example above. In some cases the submarines played big roles in sabotaging enemy supply lines, laying mines, and carried out injured men (as well as valuable goods).  It rescued pilots, of course, and deployed (as well as retrieved) shore watchers for longer term surveillance.

*flips through* Hmm, do I want to talk about mines or – Here’s an example. Hey. Trout! Trout? February 1942. Go.

Hah? Oh. Okay. According to the documents here… Let’s see… Trout…

What? The vast majority of this stuff is still buried information within U.S. Archives somewhere on microfilms since most people haven’t bothered to look through what, fifty, sixty thousand individual records? I want to make sure that we’re being accurate. In any case, to answer your question –

Here we go. USS Trout. SS 202. February 3rd 1942. 3,500 rounds of 3’’ AA ammunition to Corregidor. A drop in the bucket considering the island was hit by over 600 aerial sorties totaling more than 350 tons of explosives…

Wow, you remember that?

Heheh. Actually I uh, just looked that up yesterday. Aoba had to look up some data on Japanese aerial operations in 1942. Then we found this sad tidbit while we were looking through some old books…

Anyways. It says here that SS 202 also evacuated 20 tons of gold, silver, and securities and took them to Washington.

“And so ended the Trout’s second war patrol.”

Mhm! Of course, the Navy quickly figured out that the best submarines at the job were the largest ones by displacement. That would be the Narwhal and Nautilus. The Narwhal sometimes carried over ninety tons of ammunition and food to the guerillas or army personnel on a single run. This is in addition to the extra men that the V-boat would sometimes carry.

… I don’t need to say that these were very dangerous operations. Just meeting up with the shore party to drop this stuff off was a challenge. Still, the Army and the Filipino guerillas were very clever. For instance, in another one of Trout’s war patrols (Jun 13, 1943, war patrol no. 9), the little steam boat that was supposed to link up with her camouflaged itself using tree branches, but still managed to fly an American flag.

Anyways, so on that particular trip, the Trout’s mission is as follows:

  1. Drop five Army officers and men led by Captain Hamner at Pagadian Bay in early morning.
  2. Transfer supplies to friendlies by night & receive intel update.
  3. Scout out the areas east of Olutanaga Island for the navy.
  4. Check to make sure Olutanaga rendezvous point is clear.
  5. Pick up five Army officers lead by Lt. Commander Parsons at northwest of Liscum Bank.

I should note, too, that the Trout went above and beyond her duties in this trip –

All submariners do that, Tautau. Especially if there’s a need.

Yeah, but here it was important enough to document. It says here that the Trout was carrying far over what her recommended loadout would have been.

Couldn’t have done anything about it. Orders were orders. Somewhere up the chain something happened, they needed supplies, and we’re going to get it to them. Besides, would you really want our boys to go without basic necessities? I mean, we’re talking bullets and food here.

It says here that the Trout also carried reading materials.

…Eh, compared to the extra thousands of rounds of 30 and 45 cal bullets I think we can afford to squeeze in a couple of novels or a Bible here or there. Tell you what, if I was commander I’d have done the same thing.

The bigger picture here, though, is that the Trout’s actions were only a small part of the overall intelligence network that the US was building in the southern Pacific. The Trout, of course, successfully completed all of her logistical tasks and will be bringing home two important pieces of information. The first is the layout and force disposition of the Japanese near the areas she visited. The second is point 2, where the shore parties delivered a detailed report of Japanese shipping lanes and updates pertaining to their movements – for instance, what sort of things were being brought in or which ships were passing in the area.

This isn’t even counting the two cargo ships she got during this trip!

Now, imagine dozens of U.S. submarines all doing this during the Pacific War. Coupled with the fact that the US had cracked the Japanese naval code, and you can see how this helps war-planning immensely. This sort of special operation was a really good example of what a fleet of good submariners could do.

(We had some computer troubles yesterday… Human error is human error…)

(Also! Nobody hijacked my sub-corner this time! Yay!)

前线来信·Mail call, 美舰本·Pacific

[Mail Call] 2017/09/11 – Progress updates, misc stuff, and more

by Morgane 2017年9月12日

Hey folks. Feels like it’s been a while since I posted anything (actually it’s only been a couple of days, heh).

Basically, I’ve been sick. Then real life work picked up, so stuff has gotten busy. November and Sima have both started new jobs, so books will come at a slower pace (though still plenty of shipgirls to be done). Zero’s busy juggling a million things too, and with the advent of the new school year, our regular corps of folks return to their usual business.

Still, things are moving along. For instance, printers got unblocked last week, and our collaborators are busy mailing out preorders for the Navy Foods book. Here’s a picture of theirs for example. xD

Once that starts to go out, we’re going to sort out 2016. People are still asking for Trump posters xD So … here’s hoping that it does well. We’re probably not going to do 2018. Though, 2020 might be in the works (if we ever get that far).

Then what remains is to release Silent Service, and eventually, vol. 2. Somewhere along the way I should probably translate my own stuff. But to maintain a website update schedule is hectic, and I will probably have to slow down a tad bit. We’re getting to the point where it’s becoming difficult to manage lore – that’s why we’ve got that revamp project going on, after all.

Also, since I’m posting this on the anniversary of 9/11… I feel obliged to say something. But I’m not too sure what I want to say. What’s needed to be said has been said already. So I think remembering it would be nice. Though, looking at what’s around me… It feels that 9/11’s almost gotten forgotten already. After all, it’s been sixteen years.

Funny how stuff fades, huh? I’ve said it before. History is important. Otherwise, we forget, and if we forget, we end up losing bits of ourselves.

You’ve heard all of it before. This isn’t new. I’m just glad I’m not sick anymore and can get back to the stuff that I enjoy doing (and not enjoy doing – such this life!)