SSBN-598 George Washington Conversion Information

[Ralph --- SSBN 598]

The GW upper and lower rudders where visually the same.
Height, width.
Here is a photo of the Patrick Henry stern.
The control surfaces where air foil shaped, top to bottom.

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The draft marks as I was told, where read to the bottom of the numbers.
If the number was half covered, you could make a mistake in the reading.
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Later boats has a taller/wider upper rudder.

[wlambing]

On all US teardrop nuke boats, the bottom rudder half is larger, by far, than the upper half. This gives much better steering control when shallow, or surfaced. This also adds to the ships draft due to the extra 2-4 feet below baseline (depending on class), pre-Ohio class. God knows what those monsters have hanging down back there! I would think maybe they used the 4 foot range, too. If you can check out profile illustrations/ drawings, they usually show the bottom of the lower rudder well below the keel.

Have fun!

Bill

[aeroengineer1]

I have been looking through the pictures that I have, and it seems that when the boats launched, they had a straight rudder, but sometime later in their lives they had some sort of sensor, or other reason to add an extension to the rudder. It seems that the rudder ehight was increased by about a foot or so, but it appears that in the process that it was chopped at the 34' waterline mark, then added on. I have created a collage of pictures with them showing the change. Notice the increase in height of the fin above the launch waterline. The original launch rudder is shown in the upper right hand side.

Adam

[JWLaRue]

I'm not seeing what you are describing.....the rudders all look to be the same height, based on the draft markings, however the waterline seems to have changed?

What am I missing?

-tnx,
Jeff

[aeroengineer1]

Jeff,
I have extracted the pictures to enlarge them and post them individually.

To start the original rudder (notice how the draft mark is right at the top of the rudder and a straight leading edge)...


In the next two pictures you will see the mod'ed rudder. The draft mark is lower as well as the leading edge has a king starting about 2 feet below the tip.



Again not sure why the picture upload is screwing with my uploaded picture sizes.

[JWLaRue]

Adam,

Ahhh, now I see it. Yup, about a foot difference. Good eye!

-Jeff

[aeroengineer1]

Well, I am back at work on sizing the stern appendages. I am learning to apply some of my art class skills with vanishing points to help get some sizing of these components. It is not perfect, but here are some of my in progress pics. Once again, sorry for the small size. Each time I upload a photo, it seems to resize them, and I do not seem to have control of how they appear. These pictures are 1920 x 1080 in actual size.

In this exercise, it appears that the trailing edge of the stern planes is aft of the trailing edge of the rudders by a few feet. Both pictures confirm this finding. The lower rudder appears to be longer than the bottom of the hull (working to confirm this, perhaps it was never intended to bottom boat). Stern planes are narrower than the rudders are tall.

[wlambing]

On the US boats, depending on class, the lower rudder is 2'-4' below baseline (keel). With the fixed stabilizer and the moveable stern planes flap, the stern planes are about 4x the surface area of the sail planes. You are correct that the rudder and stern planes are not symmetrical, that is different lengths when measured between their axis points. None of our boats are. Why are you working from pictures when there are drawings and illustrations available, probably some really good ones through this site, and for sure in past issues of the SCR? And no, generally it is not desirable to bottom a boat! It can be done in extremis situations (USS Narwhal, Hurricane Hugo), but unless something has changed recently, we have no procedure to do that.

Bill

[aeroengineer1]

Bill,

The reason I am doing drawings for this boat is because good ones do not exist for this one (at least I would be happy to be proven wrong). No one has been able to get a hold of the piping tab for this boat. There are some junk "blueprints" you can find on ebay that, while they look official, are very incorrect. When I pinged the seller about the heritage of the plans, he stated that they were not intended to be in any way accurate. There is one very grainy picture that can be found that looks like it may be the real deal, but it is so grainy, it is hard to use for anything other than a quick reference. Hence with the lack of drawings, I am piecing something together that is actually coming along very well and will have as much detail that can be afforded based upon the data sources.

As for the rudders and stern planes being symmetrical, I knew that they did not have the same shape, the question is if they have the same span. As to the rudder being below the keel, I also have my doubts on this, and I will follow it ip in a post here in a few minutes once I finish getting the pictures together for it.

If in anything, though, that I may be inaccurate in, I am really happy to be proven incorrect. If a set of piping tab plans magically appeared after over a decade of nothing, I would be doing back flips (really, no sarcasm here, I would love this)!!!

[aeroengineer1]

Draft Marking Question

Ok, I have learned that draft markings are to be read at the bottom of the number, and that they are 6" tall, and that there is a 6" space between the top of one number and the bottom of the number above it (see this link for more information on the topic). This is pretty easy to understand. As I was going through trying to do some sizing calculations for the GW, I came to realize that the rudder would be below the bottom of the hull. This seemed interesting. I did know that some of the later classes had rudders that were longer than the bottom of the boat, but some of the other numbers were not quite adding up when I was doing my calculations.

I decided to look at some other boats in the effort. I have a fair amount of info on the Skipjack class, so I started there. We know the Skipjack to have an upper and lower rudder that is symmetrical. This can be seen in the cropped view I have here of the side view of the hull. It is also noticed that the upper and lower rudder do not extend past the maximum diameter of the hull. The hull diameter is somewhere between 31.5' and 32' (depends on your source, though most seem to be around 31' 8").



If we take this as truth, then the top of the rudder should have a draft mark of 31' such that when fully submerged would be ~31.5'. But, when we look at a picture of a Skipjack rudder it shows that the top mark is 33, though it is tall enough that 34 could have been marked and it would have been right at the top of the rudder.



Why is this the case? My guess is that the boat when on the surface (when these marks have any real value) it is designed so that the bow sits high, and the rudder lower. Hence, the markings would not be in accordance with the propeller shaft axis (Skipjack is mostly a hull of revolution), but the waterline as it sits in the water. This would also mean that the decks had an incline while at port.

Can anyone confirm this, or provide a different explanation?

Adam

[wlambing]

Adam,

I am SS qualified on 4 different US submarines, two of which were boomers. I currently provide support for the last SSBN 616 and SSBN 627 class submarines in the universe. The lower rudder protrudes below baseline. Period. Draft is measured from the baseline, except in the case of the rudder, where it is measured from the lowest point below baseline. In your picture of the rudders, imagine dropping straight down 33', and reaching out with your hand. You would feel the bottom edge of the lower rudder blade, and likely some bottom goo. At forward points where draft numbers appear, the keel is the measurement, extreme bottom, at the centerline of the ship. Inport, draft and trim, as well as list, are recorded 1/2 hourly to ensure that an evolution or material condition does not endanger the ship.
The ships trim on the surface is not the designed trim, which is the natural angle of the ships main axis. Surface trim is variable due to quantities of water in the variable ballast tanks onboard. Some ships are designed to 0 degrees, some 1 degree, some 1/2 degree down. Depends on the class. As to span of the rudder vs. stern planes, they typically do not have the same span. This is what I was trying to convey previously. The rudder would be taller than the stern planes width. Want to have some fun with this? Look at the Brit boats. Their upper rudder is huge compared to the lower. Opposite of what we do.
Keep in mind, too, that GW is NOT a Skipjack! She was modified as required to fulfill a much different roll in life. Adding the missile compartment completely changed her naval architecture, plus she received alterations throughout her career to improve different aspects, and she ran aground at speed in the Irish Sea later in life, causing great damage to the lower rudder, that protruded below baseline. Nathan Hale (Nathaniel Greene?) did similar and completely removed the 4' protrusion!
I can't do it from here, but in your stbd quarter dry-dock pic (color); if you run the green line at the top of the blocks all the way back through the lower rudder blade, it looks to me like you will see that the blade extends below the green line by at least 2'.
Have fun!

Bill

[gepard335]

Bill,

It's been a long while since someone posted on this thread, but I thought might as well clear this up in case someone (like me) searches for info on the George Washington.

You are correct that quite a few U.S. boats have rudders that extend beyond the baseline. However, you are incorrect that the lower rudder is larger than the upper rudder. In fact, the opposite is typically true (in terms of both area and height). The 608, 616, and 640 boats in particular had enormous top rudders compared to their relatively small lower rudders. The Los Angeles class also has a larger upper rudder, but all of our other submarines have had rudders with very similar sizes top and bottom. As I'm sure you know, it would be disadvantageous to have a very deep lower rudder, and if you needed more vertical area aft and couldn't make the upper rudder much taller, the solution would be to add vertical surfaces to the horizontal stabilizers instead of extending the lower rudder (you could also increase the chord of the lower rudder). Also, I faintly remember reading that having a larger lower rudder would increase snap roll, which is undesirable.

And you are of course correct that a George Washington was not a Skipjack. However, all of the documentation I have (much of it from NARA) shows that the bow and stern are nearly identical to a Skipjack (more specifically the Scamp and later boats, which had an improved propulsion plant). I have yet to find a substantial difference in their structures in the bow and stern besides the control surfaces. The myth you will find in some books that a complete Skipjack was "cut in half on the ways" is false (the "cutting" was done on paper), but they used as much design material from the Skipjack as possible to speed construction. The biggest change to the Skipjack ends seems to have been in the forward torpedo room (due to a smaller number of reload torpedoes), although this likely did not change the pressure hull structure whatsoever.

Jacob