Tuesday, February 26, 2008

Public Service Film No. 1: Introductory Propulsion

Well, between funky work schedules and travel-inhibiting snows, it has been longer than I would have hoped since my last visit to SLATER. It has been my intention to withold my current assignment until I have completed it. I'm still wavering at this point, in that an incomplete story is not that interesting, so based on that, I think I'll continue to play my cards close to my vest and instead go a little more in-depth on the ins and outs of propulsion aboard SLATER and all CANNON-Class DEs.

We'll begin at the beginning. While underway, the man in charge of the ship was the Officer of the Deck (OOD). Of course the CO is in overall command, but the details were handled by the OOD, especially when the CO was asleep. Courses, bell orders (speeds), and other such minutae was the OOD's responsibility. So, let's devise a scenario: the OOD wants, for whatever reason, to change the speed of the ship. This is no emergency, so there's no need to alert the CO; this is merely a routine matter. The OOD will give the new order to the lee-helmsman (as opposed to the helmsman, who is actually steering the ship), for example "All ahead two-thirds" or "All ahead flank". The lee-helmsman will acknowledge that order and operate the Engine Order Telegraph (EOT). Anyone who's ever watched the movie Titanic or any old war movie will be able to pick out the EOT in this photo. For the benefit of the cinematically-challenged, I have marked it in the photo of the pilothouse.

Time to dispel a common misconception: the lee-helmsman, when he operates the EOT, has absolutely no control over the engines. None. It's an Engine Order Telegraph; all it does is transmit the order to the enginerooms. The watchstanders in the enginerooms are the only people who can control the speed of the ship. Of course, our watchstanders in the engineering spaces are paying close attention to their EOT and notice when the order comes in; but just in case, there is a bell that rings when the order comes in, hence the term "answering bells" for getting underway; when the order comes in to the enginerooms via the EOT, the watchstanders have a basic panel copy of the EOT and they acknowledge the order and let the lee-helmsman know they are responding to his order.
Complicated enough? It sounds that way, but in reality it's quite simple. So now the enginerooms have a new bell to answer, let's look at how this is accomplished. There are four engineering spaces aboard CANNON-Class DEs. They are commonly called "enginerooms", which is technically incorrect. Two of them, the first and third, are enginerooms, they contain the engines, GM 16-cylinder diesels putting out 1700 horsepower apiece. There are two of these monsters in each of the two enginerooms. The shafts from these diesels actually go through the bulkhead to the second and forth engineering spaces, the two motor rooms. The four diesels turn four large generators, which are wired to four electric motors, two on each main shaft, and each main shaft turns one screw (propeller).

So, why was this ship designed this way? Several reasons. First, they couldn't hook the diesel up to the screw directly: a ship of this size needs a relatively lower screw RPM to be effective, otherwise it would just froth up the water and the ship would go nowhere. During peacetime they would use a large transmission called reduction gears to slow the shaft RPM to a usable speed. The problem is that reduction gears are difficult to produce (and therefore produced slowly). While the DEs were being built at breakneck speed (the record is 23-1/3 days), the builders couldn't wait around for reduction gears to be produced.

Secondly, reduction gears are expesive. Very expensive. So expensive, in fact, that to this day, the Navy does not buy the reduction gears we put in our ships: we lease them. When the ship is being scrapped, the reduction gears are inspected. If they're still good, they're put into a new ship being built.

Thirdly, this diesel-electric design means that if one diesel or generator fails, the other diesel-generator pair can turn that shaft, admittedly at a slower speed, while the other diesel-generator pair is powered off and repaired. So rather than running at a maximum of 1/2 speed while one of the two shafts is out of service, the ship can theoretically reach 3/4 of maximum speed, since one of the four diesel-generator pairs is out of service for repair. Additionally, there is no need to have all four diesels running at all times: while escorting convoys, one diesel-generator pair on each shaft would be more than enough to keep up with the brutally slow convoys, thereby extending fuel economy.

Speaking of fuel economy, that's fourth. Direct reduction gear coupling produced as fuel efficiency of about 70 gallons to the mile. No, not miles per gallon, gallons per mile. The diesel-electric setup cuts that nearly in half, to a mere 35 gallons per mile. In wartime, when resources are stretched to the breaking point, this is a crucial point.

Also in each engineroom is an additional 8-cylinder diesel. These two diesels are connected to another, you guessed it, generator. These two generators supplied all the electrical loading for the ship, lighting, winches, electric ranges, everything. And, just to be safe, there is a 3-cylinder diesel that is an emergency electrical generator, if everything else fails. I can't confirm this, but I have a feeling that, in a pinch, there was a way to cross-connect the generators used for propulsion into the power system, but I'll have to do a little more looking into this theory.

Friday, February 1, 2008

Winter Quarters

Without trying to introduce any drama, let's just say that this winter has been somewhat interesting. Of course, this being my first winter outside of the Southeast, that should not come as a surprise. Having qualified on the second plant at work, I am back at my original plant to re-qualify as a staff instructor. What does this mean to you, my loyal fan base? Simply that I will be in the area for another two years, and should be bringing you more stories and information about SLATER, rather than having to shift the focus on whatever it is that I would be doing at my new command.

The practical end of the fact that I've just had to move lies in that, rather than having photographs of my most recent work on the #1 3" gun, my camera is buried in a box. Which box, I do not know, beacuse among the contents of the first box I packed up was my drawer of miscellaneous items that I felt I could do without the longest. The drawer that contained my Sharpie. Not feeling the need to dig it out halfway through packing, all of my boxes are unlabeled. It'll make unpacking feel more like Christmas: "I wonder what's in this one..." As such, I've noticed that there is a group of photos that I've never bothered to write about, so I figure this is the perfect time to use them.

The biggest use of DEs during the war was anti-submarine warfare. DDs took care of most of the work in the Pacific where aircraft were more of a threat. In the Atlantic, the foe was found under the sea. As such, the weapons needed to attack this foe also had to go beneath the waves. Low-tech but powerful, the weapon most used was the depth charge. (Pictured is a cutaway display with the entire fusing mechanism installed. Well, without the explosive charge, of course...)

Depth charges are also known as "ash cans", because that's what they resemble. A depth charge, or "d/c" is a metal barrel 28" long and 18" across across filled with high explosives. The d/c in the photograph is a 300 lb. Mark VI, and was fused hydrostatically. Now, I'm going to hit a brief physics lession here, so for those of you uninterested in figures and formulae, feel free to skip down to "END OF PHYSICS LESSON"

Everyone knows, if for no other reason than watching old submarine movies or SCUBA diving, that the deeper you go, the more water pressure builds up. This is due to the virtual incompressibility of water and gravity. Atmospheric pressure is about 14.7 pounds per square inch. This varies from day to day, and is easily calculated from barometric pressure: 29.92" Hg on the barometer is approximately the 14.7 psi that everyone is familiar with. The fluctuations in the barometer from day to day are due to several factors, one of which is the density of the air. Of course warm air is less dense than cold air. Another factor is height/depth. Also, the actual thickness of the atmosphere at a certain point, measured from the surface to the top of the atmosphere, varies slightly daily.

Okay, so the formula for all this is P=pgz/c, where P=pressure (lbf/in^2), p=density (lbm/in^3) and z=height/depth (feet) and g=gravitational acceleration (32 feet/sec^2) and c=32 ft*lbm/lbf*sec^2, a constant that corrects for lbm (pounds mass) and lbf (pounds force). The two are equal on earth, but a 10 lbm ball on earth will still be a 10 lbm ball on the moon, although it weighs less than 10 lbf. Confused yet?

Okay, so what does this mean for us? Water, pure water has a density of about 63 lmb/ft^3. I say "about", because like air, water will become less dense with higher temperatures and less dense at lower temperatures. But that's pure water. Seawater is more dense due to the salt, fish poop, et cetera dissolved in it, something like 65 lbm/ft^3. But this changes, because the salt and fish poop dissolved in the seawater changes from place to place. But despite all this, we can assume that the density of saltwater will remain constant. Since we are still on earth, gravity will remain constant, and c, our constant, is always constant. So since P=pgz/c, the only thing that changes is z, depth. As such, we can safely assume with reasonable accuracy that at depth "z", we will always experience the same "P". On this principle the fusing of the d/c is based.


The fusing mechanism is a pressure switch, basically. Before being launched, the d/c will be set to the depth that the sonar station and Combat Information Center (CIC) believes is closest to where the U-boat is or will be when the d/c gets there. As the d/c sinks deeper, metal bellows (inside the brass sleeve in the left and the black "cup" on the right) will expand, putting more pressure on the firing spring. When the bellows expand enough, they will press on a small rod in the middle of the firing spring. The firing pin is in a sleeve, and in the sides of the pin are three ball bearings that prevent the pin from sliding completely through the sleeve. When the bellows press on this rod, the ball bearings retract inside the pin. With nothing restraining the pin, it shoots through the sleeve, setting off the primer. The primer sets of a 5 lb. booster charge (the grey can in the cutaway picture) which in turn sets of the 300 lb. main charge.

No exact figures are known, but the best calculations suggest that the kill radius on a d/c was a mere 30 feet. If the d/c went off within about 70 feet of the U-boat, damage will be significant, but rarely fatal. Beyond that, and it was only dangerous to the fish. The significance of this to the crews of DEs is that they would have to be outside of this kill radius themselves or risk damage by their own d/c. Of course the deeper the fuse setting the less of a problem this was.

The DEs had two methods of delivery. The first was a simple roller rack on the stern of the ship. Angled astern, a d/c could be rolled off the ship into the water. The second was the K-gun, which were on the sides of the ship. The K-gun could launch a d/c over the sides and cover a wider area than the racks alone. As sonar got better and crews gained more experience, the depth charges became more deadly to the U-boats and their crews. Approximately 40,000 young German men served on U-boats during all of World War II. Just under 30,000 of them never returned to port. This casualty rate, upwards of 70%, was surpassed by only one other community of fighting men on both sides during the entire Second World War: Imperial Japanese kamakazi units.

Tuesday, November 27, 2007

The Big Move

To begin with, having no good reason for not having posted in nearly a month and a half, I won't bore you with any. The biggest reason is inertia; finally having overcome that obstacle, let's get on with it. I had been planning to go in-depth on depth charges, but something else has come up to make depth charges No. 2 on my list.

No. 1 is the move. Monday it was decided was to be the day SLATER would be moved the mile down the Hudson to the other side of the river. Since the propulsion plant is completely non-functional, we made the move with the help of a pair of tugs. These two tugs move us on a purely volunteer basis, so we have to go whenever they have time. The big reason I mention this is that I had a mere 3.5 hours notice that the move was being made. Needless to say it took only 45 minutes for me to get out the door.

Upon arrival, there was a crane standing by to remove the gangway and a sizeable contingent of line handlers both ashore and aboard. But as soon as I stepped off the gangway onto the deck, I paused. Something was different. Something didn't feel right. It took me a mere second to realize what it was. But soon the alien vibration in my feet became clear as day: there was a diesel running somewhere! Rounding the No. 3 gun, I became aware of the blue smoke exhausting from the Emergency Diesel. By now, the rhythmic "thunk-a-click-a-thunk-a-click-a" was audible and only grew louder as I descended the ladder into B-4. At the foot of the ladder I was met by Carl, to whom I immediately exclaimed: "Hot damn, it sounds like an engine room now!" I don't know why the sound of that diesel made me grin as wide as it did, but after chinning for a couple of seconds, I went down the ladder to the lower level where I met Gus and made the same observation to him that I had made to Carl. Again, I don't know why seeing that diesel turning over, warming up to generate the electricity for the ship suring the move, seemed like such a beautiful sight to me, but it was. As much as I wanted to stay part of the Engineering Department for the move, Deck Division needed all the hands they could get, including mine.

After helping put canvas covers over the forward two 3" guns, the first tug arrived and began attaching itself to our starboard side forward. Once that was accomplished, we began to single up all the lines and the crane removed the gangway while the second tug busied itself attaching itself to the starboard side aft. Through the cold drizzle that fell throughout the process, one by one the singled lines were cast off and hauled aboard. Of course the hauling was my job, along with the other two volunteers who were assigned to the fo'c'sle with me. And then, ever so slowly, SLATER drifted away from the riverside and into the middle of the channel. It was a wierd feeling. The ship was dead for all intents and purposes, but the tugs lashed tightly to our side transferred their rumblings and vibrations into the hull of SLATER. It was almost like some sort of nautical artificial respiration. For the 20 minutes or so it took to make the move, SLATER felt like a ship and not a museum.

Now, here's where training took over. As we pulled lines aboard, one after another, the fo'c'sle began to look like a plate of spaghetti. I didn't notice this until after I had snapped several photos, but as soon as I did take notice, I thought "Oh, no. If 'Boats' sees this mess, he'll be pissed!" Some of the lines had been laid out down the port side, but the forward most lines has just been left where they lay. I immediately got to work, "faking down" the lines that were to go through the bull-nose. Halfway through this, I reflected on how silly that was. There were no Botswain's Mates aboard, and even if there were, they might have made a remark about the mess, but wouldn't have expected anyone to fix it. But, to hell with it, I couldn't let those civilians think that's how we do things in the Navy. I won't say that when I was done the fo'c'sle was inspection-ready, but it wasn't bad at all.

During my adventures in marlinspiking, the tugs, one at a time, had transferred themselves to our port side, because the ship would be moored on the starboard side. Slowly but surely, the tugs moved us into position, heaving lines were thrown across, and lines were singled up. Of course, this was not as easy as it seemed. We would put turns in the line around the bitts, and then word would come "Three feet forward", so we would either need to take in or slack the line three feet, depending on the orientation of the line. Back and forth, feet at a time, SLATER was moved into just the right position, the singled up lines were secured and then doubled up. Their jobs done, the tugs moved off, but not before engaging in some horeseplay that proved to be then antithesis of a tug-of-war.

Shore power was connected, the diesel secured, and the steel cables were passed ashore to add that extra bit of security to the mooring operation. All too soon, it was done. I can say that I have some sea time on a Navy ship, assuming that you apply liberal definitions to "sea" to include the Hudson River and "Navy ship" to include a 63-year-old DE incapable of moving under her own power. But I can say that I have more recent nautical experience than all of the students and a good 98% of the staff at work. That may seem like a minor point, but I'm proud of it.

I was on a schedule, so I had to get a ride back to the Albany side of the river before mooring was 100% complete. But once I got to my car, I took a second to snap a photo of where SLATER stood when I first saw her. But over the coming winter months, there will be plenty of heavy maintenance to be done, and I hope to be elbows-deep in it. Of course, I already know what my first project will be. I won't spoil it so as to keep intrest piqued, but let's just say that once I'm done with this, I may be eligible to cross-rate as a Gunner's Mate.

Saturday, October 13, 2007

More School...

Well, since I'm still in the Albany area for another school for the Navy, you would think I would have time to get more done on the page here. But I decided that last week would be a good time to go back home on a week of leave, and so I did. Being a few hundred miles away kind of kept me away from the ship for a bit. But I figured I'd drop a line to let my loyal fans (all three of you) know that I didn't drop off the face of the planet.

Now, I'll apologize from the start that I really don't have much to add here. Hopefully that will change tomorrow, and if it does, I'll go for the unprecedented two-updates-in-a-single-weekend. But don't hold your breath.

This weekend was the 75th anniversary celebration for the Port of Albany, and the festival was held at our pier. There were plenty of folks on hand, and we had the ship open free of charge. But to deal with the masses (I've heard estimates of 1,000 to 1,800), we shortened the tour route and stationed guides along the way to give some brief points before the crowds moved along. So, other than two restroom breaks and a lunch break, I stood in forward bearthing and repeated the same five or six sentences for 6 hours, along with answering a question or two. I debated taking photos of all the folks who passed through, just to spice things up, but decided against it.

There are also two other important events that were commemorated today. Of course the Navy had yet another birthday, but on this day, 13 October, in 1944 a small portion of the US Navy won the most improbable victory probably in its entire history. A handfull of destroyers (DDs), destroyer escorts (DEs, like SLATER) and escort carriers (CVEs) faced off, toe to toe with the main Japanese battlefleet that was on its way to Leyte in the Philippine Islands to wipe out the American landings there and forced the Japanese to turn back. It's the best David-and-Goliath story I can think of since, well, David and Goliath.

I haven't the space or ability to do this subject justice in this small forum, so I apologize, but I'm going to make the closest thing I can to a demand. I very highly suggest to go to the library or the bookstore and get a copy of The Last Stand of the Tin Can Sailors by James D. Hornfischer. I'll make it easy for you. Click on the link at the bottom of the page and you'll go to the page to buy the book on Amazon.com. If you want to know what heroism is, you'll find it between the covers of this book. There were several places in the book that I had to stop and think about exactly what I had just read. And a few times, after I reflected on the heroism and sacrifice and plain horror that these men faced, I had to put the book down and dry my eyes. I can't say enough to do the book and the story behind it justice. Read the book. Read it, and you'll see what I mean. If this book won't make you proud to be an American, nothing will. When you're through with it, you'll know without a doubt exactly what a hero is.


Wednesday, September 19, 2007

It's Not Easy Being Green

Of course that title makes no sense unless I were green. But according to common folklore, radiation makes you glow a faint greenish hue. And God know's I've been up to my neck in nuclear power these past weeks, getting ready for my final boards that will prove that I have learned enough to go to the next school. And I thought 5 1/2 years in college was bad...

So, to make up for my intransigence, I will begin with what I promised last time: 20mm guns. This photo from a page I found today, http://www.savetheptboatinc.com/ shows a single 20mm mount. The nine mounts (three forward, four midships and two aft) aboard SLATER are twin mounts. Designed by the Swiss during the closing days of World War I and firing explosive shells, the 20mm was a common AA mount whose effectiveness was diminished only by the increasing speeds of aircraft. With an effective range of ~2000 yards, the 20mm gunner would have only the eights or so it took a kamakazi to travel those 2000 yards before impact to destroy it. But the situation is not as dire as it sounds, for the 20mms were the last line of AA defense.

Previously one of the mounts has been really done over in style, and we are in the process of working on a second mount. The gun here has been removed from its mount for work. (Al Vanderzee gives one of his award-winning tours in the background.) Of course the plan is to get the gun looking good, not functioning. The steel plug welded in the barrels of the 2os before the ship was returned to us would make those efforts fruitless anyway.

The image to the right is details the top of the 20, where the magazine would sit. The magazines containted 60 rounds of ammuntion apiece, and would be passed belowdecks when empty to be refilled in a clipping room and then returned full to the gun for subsequent re-emptying.

To be honest, work had been weighing upon my mind quite a bit over the past few weeks, and it showed. My tours were not quite up to snuff on Thursday, and on Friday, I asked if there were any odd jobs to be done around; and of course there were. I was tasked first with notching some covers that were to be screwed to the top of the ammo lockers located on the centerline of the O-1 deck. The fabricators who made them put the notches in the wrong place, and to make them sit correctly, that problem had to be fixed. Of course I had no way to fill in the incorrect notches, so we had to settle for making more notches where they should have been.

And the tools of the trade: the hacksaw for making the cuts, the channel locks to wiggle the tab out, the file for removing the burrs and rough edges, and the coffe because, well, because I'm in the Navy.

The rest of the day, honestly, was spent doing a little piddling around, doing odd jobs, replacing a valve that I had cleaned previously, organizing things, and the like. I got a brush up on the ins and outs of CIC, took the covers off some radar sets and poked around, and then took care of the banging, scraping sound that had been annoying me most of the day.

The day had been windy, and the signal flags could have been starched for all I knew. One of the radio antennas on the port side had been rattled and twisted loose from the turnbuckle that held it in place just below the O-3 level (three floors up from the main deck). The antennas are fixed on the yardarm that crosses the mast, and on the side of the superstructure. The turnbuckle had to be reattached. Sounds easy? Well, no matter how we tried, when we leaned over the rail of the O-3 level, we were still a good two feet away from the turnbuckle. The wing on the O-2 level was a good 10 feet away. There was only one option: someone had to climb up two stories of superstructure. You'll never guess who did it. Those who do not like heights, you've been warned.

Just another day in the life of a SLATER volunteer. Wouldn't trade it for the world.

Monday, August 27, 2007

If it Moves, Salute it; if it Doesn't, Paint it.

That bit of wisdom has been in the Navy longer than anyone knows, which means it must be true. I found this past weekend that enginerooms do not move. As such, I spent a good amount of time painting B-4.
The immediate concern was the deckplates. I believe I have failed to mention previously that most of the deckplates on the upper and lower levels of B-4 (on the starboard side) had been painted previously. The entire division, all three of us, were concerned
with the gratings these two past weekends. On the port side of the upper level, rather than solid plates of steel for the deck, there are gratings, basically a catwalk, much like you would see above subway lines for ventilation. The lower level of the port side has solid deckplates. All of the decking, solid or grating, is not fastened down, but sits upon a framework of angle-iron. This allows for easy access to what would otherwise be generally inaccessable areas of the miles of piping that wind throughout the einginerooms.
The gratings had to be lifted out of place, taken up to the deck and then across to the picnic area ashore. After that, Gus and I ran an air line from the manifold in B-3, up to the second (O-1) deck, fastened it to a 20mm gun tub, and then ran it across to shore. Once the gratings were laid out, then the paint sprayer was unleashed on them, Gus and I taking turns changing the dull metal to shipshape gratings worthy of the finest of enginerooms. This was a multi-day project in and of itself.
This past weekend was more of the same. The upper level gratings had been returned to place during the week, and based on the "before" photo you saw, the difference is apparent. The upper level having been done, the same process had to be repeated for the deckplates in lower level.

But the process is a bit more involved than I first stated. Of course the deckplates have to be cleaned up, but to replace them on top of angle-iron that had not itself been chipped and painted would be, well, irresponsible. So most of Saturday found me with a scraper bar and rag going through 60 years worth of paint, oil, and grease. I kid you not, on some of the areas, I removed a 1/4" thick layer of dirt, oil, and grease and an additional 1/8 - 1/4" of paint. But in the end, everything looked fine, with the new paint applied. This Monday, while I'm taking a day off between work and USS SLATER, Gus and Carl will most likely be back at it, painting and then replacing the deckplates. Once that is done, B-4 will look 10 times better, but with still a ways to go.

Next, I think, will be B-3, the engineroom forward of B-4. Recently the welders cut a hole in the bulkhead separating B-4 and B-3, and a watertight door is scheduled to go in the hole. All original accesses to the enginerooms are through small hatches and steep ladders, so these doors will make the spaces more accessable for all our visitors.
Well, since I have been dink in posting, I suppose I have to drop a little teaser here. You see, they are doing some work on one of the 20mm mounts, and I did manage to get a few good photos. But, I'm just too darned tired to post and talk about them now, so I guess you'll just have to stick around and check back...

Monday, August 13, 2007

Fits and Starts

Well, folks, I admit it's been a while since I last posted, and there are a few reasons for that. One is that recently, I really haven't been doing anything other than messing around with the same valves on the mess deck, making them look much better and really taking my time for it. Second, or more of a continuation of first, is that I have been dedicating more of my time for tours recently. My work schedule has put me in Albany more during the week, and most of the maintenance crew comes in on Saturdays. So the maintenance I've been doing recently is light, one-man work; and there's really nothing that exciting about that.

However, I promise that after this coming weekend, there should be more interesting stories to relate and pictures to share. I'll be back down on a weekend, and there should be some more complex and detailed work to be done that will make for better reading and photography. Until then, I hope that you won't be too put off by my apparent leave of absence.