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The USS Texas going to dry dock!

Mikel said:
I thought the foam had been there longer.

The sad part is that no matter how many millions of dollars they spend, they are only delaying the inevitable. It is impossible to stabilize a gigantic structure made of steel, with millions of places for water to leak and accumulate.
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Needs be in Sand Hollow.
 
1948
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They mentioned the repair would be extensive and probably ruin the rudder. The slight angle didn't stop them from towing it so they're not spending the money.
 
Firstram said:
They mentioned the repair would be extensive and probably ruin the rudder. The slight angle didn't stop them from towing it so they're not spending the money.
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How rusty can the post/bushings be? Drill some access holes, squirt in magic liquid, heat the snot out of it and winch it over like they did on the Great Eastern 170 years ago.
 
plym49.2 said:
How rusty can the post/bushings be? Drill some access holes, squirt in magic liquid, heat the snot out of it and winch it over like they did on the Great Eastern 170 years ago.
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If I remember correctly, they welded it in place to help seal it off. It was a quick ”fix” when they tried to restore it years ago.
 
Also, the rudder position is the last order given to the helm when she was in service. They don't feel it's right to change it now.
 
Quick & Dirty said:
Also, the rudder position is the last order given to the helm when she was in service. They don't feel it's right to change it now.
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Yeah but that's a pretty lame justification. They had no problem removing her screws and shafts.
 
plym49.2 said:
How rusty can the post/bushings be? Drill some access holes, squirt in magic liquid, heat the snot out of it and winch it over like they did on the Great Eastern 170 years ago.
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Very rusty, not to mention it being welded together. Certainly it could be done, but would probably require removing the rudder, rudder stock, steering system, etc., and would entail a fair bit of damage to said parts. Also cost quite a bit of money and time in dock.

All to what end? No reason anyone should really care, and 99% of folks would never know one way or the other. Much better things they can spend money and effort on.
 
Pocahontas said:
Even victory, in a permanent drydock, is having problems because of how she is sitting. All this ships are money pits it depends if you think they are worth preserving for future generations.
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Yep. Also notable that it's not really immersion in seawater that's the issue, it's water accumulating inside tanks and voids from leaks, which will happen regardless (rain, condensation, etc.) The blisters are a particular issue because the design results in narrow tapered ends at the bottom where water will pool and can never be completely removed. Note how the frames taper around the turn of the bilge and how you can see much worse rust on the hull plating at the bottom.

More significantly, graving docks big enough to put her in are few and far between, and building something as dry berth for her would be very difficult. Possible for something small like SS-569, but much different story for a 600 ft 27,000 ton ship. Even then, the dock still needs maintenance and pumping.

The issues with Victory and hull deformation are because she's a wooden hull. No reason a steel ship couldn't sit on blocks indefinitely if the setting is properly designed.
 
aczlan said:
The things you learn on a 4x4 site that you weren't expecting to learn...
Thanks sdmuleman.


Aaron Z
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plym49.2 said:
Absolutely - that was terrifically educational! :beer::beer::beer:
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Feel free to ask any other docking questions - I qualified as a docking officer at one of the naval shipyards and have been more or less in charge of something like a dozen different docking evolutions, so it's interesting to try and remember the various details and explain things. I always found it an very interesting mix of ancient technology and modern - the tools and techniques of woodwork and docking are largely unchanged from 200 yrs ago, yet we're docking 100,000 ton nuclear ships and using fancy computer tools alongside a guy with a tape measure.

As an interesting note, dimension on the dock builds use something called shipwright math - instead of a length in feet/inches, it's a set of 3 groups of numbers - feet, inches and 8's. So instead of writing 5' 8-5/16", they would instead write 5 8 2+, and all the block dimensions are listed this way. Takes a bit to get used to.

Back to the original subject, it looks like what they did with Tex is to use marker poles for alignment. In the background of some of the videos you can see a large (~8" diameter) vertical pole with braces welded to the dock floor. What they did was use 2 of these, one fwd and one aft, with the bases precisely measured off the block build such that when specific spots on the ship where up against the poles she would be in the right spot relative to the blocks.

It's also easier on her because the build is essentially all flat, so the tolerances are much greater - as long as the keel and docking keels land somewhere close to centered on the blocks it's good enough. IIRC if you pay close attention to some of videos you will see that either bow or stern is not centered on the keel blocks.

Up through the early 20th century, most docks had a row of flat keel blocks and ships were relatively narrow in profile, so all the really needed was keel support. So ships would be brought in, roughly centered in the dock so the keel landed on the blocks and then after landing side shores would be wedged in between the hull and the sides of the dock for stability, supplemented by bilge shores when the dock was pumped down. This is why older docks generally have stepped sides.

s-l500.jpg
Because all you needed were flat keel blocks, exact location of the ship was not critical. As ships got bigger, additional blocks were needed, but generally still just flat blocks. Texas is a good example - docking keels are flat, and in fact carried fwd and aft below the curve of the hull to allow the use of flat blocks. The below picture of New York sinking shows this is good degree with 2 docking keel extensions fwd/aft on each side. The inboard set likely was original, and the outboards installed with the bulges.

80-G-498141-A.jpg

In contrast, modern docking systems use blocks shaped to match the curves of the hull, which makes a much higher degree of precision necessary. In submarines for instance, the block build is very much a cradle, with the side blocks and fwd/aft end of the keel blocks being on the order of 2 ft higher than the keel line. Also, modern boats have lots of sensors, hull openings, fittings, etc. that need to be kept clear of the blocks, which also makes it very important to know exactly where the blocks go and where the ship lands.
 
sdmuleman said:
Feel free to ask any other docking questions - I qualified as a docking officer at one of the naval shipyards and have been more or less in charge of something like a dozen different docking evolutions, so it's interesting to try and remember the various details and explain things. I always found it an very interesting mix of ancient technology and modern - the tools and techniques of woodwork and docking are largely unchanged from 200 yrs ago, yet we're docking 100,000 ton nuclear ships and using fancy computer tools alongside a guy with a tape measure.

As an interesting note, dimension on the dock builds use something called shipwright math - instead of a length in feet/inches, it's a set of 3 groups of numbers - feet, inches and 8's. So instead of writing 5' 8-5/16", they would instead write 5 8 2+, and all the block dimensions are listed this way. Takes a bit to get used to.

Back to the original subject, it looks like what they did with Tex is to use marker poles for alignment. In the background of some of the videos you can see a large (~8" diameter) vertical pole with braces welded to the dock floor. What they did was use 2 of these, one fwd and one aft, with the bases precisely measured off the block build such that when specific spots on the ship where up against the poles she would be in the right spot relative to the blocks.

It's also easier on her because the build is essentially all flat, so the tolerances are much greater - as long as the keel and docking keels land somewhere close to centered on the blocks it's good enough. IIRC if you pay close attention to some of videos you will see that either bow or stern is not centered on the keel blocks.

Up through the early 20th century, most docks had a row of flat keel blocks and ships were relatively narrow in profile, so all the really needed was keel support. So ships would be brought in, roughly centered in the dock so the keel landed on the blocks and then after landing side shores would be wedged in between the hull and the sides of the dock for stability, supplemented by bilge shores when the dock was pumped down. This is why older docks generally have stepped sides.

s-l500.jpg
Because all you needed were flat keel blocks, exact location of the ship was not critical. As ships got bigger, additional blocks were needed, but generally still just flat blocks. Texas is a good example - docking keels are flat, and in fact carried fwd and aft below the curve of the hull to allow the use of flat blocks. The below picture of New York sinking shows this is good degree with 2 docking keel extensions fwd/aft on each side. The inboard set likely was original, and the outboards installed with the bulges.

80-G-498141-A.jpg

In contrast, modern docking systems use blocks shaped to match the curves of the hull, which makes a much higher degree of precision necessary. In submarines for instance, the block build is very much a cradle, with the side blocks and fwd/aft end of the keel blocks being on the order of 2 ft higher than the keel line. Also, modern boats have lots of sensors, hull openings, fittings, etc. that need to be kept clear of the blocks, which also makes it very important to know exactly where the blocks go and where the ship lands.
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Wonderful! I love learning about the details of different processes. I imagine that nowadays there is GPS supplementation as well.
 
plym49.2 said:
Wonderful! I love learning about the details of different processes. I imagine that nowadays there is GPS supplementation as well.
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To get around line of sight issues perhaps, but beyond that a standard laser "total station" would be sufficient, IIRC from earlier in the thread they have benchmarks around the dock and can calculate the angle/distance from any of those to any of the blocks. The earlier post:
sdmuleman said:
Couple pictures to illustrate:
Bow of a carrier, target is right on the centerline of the stem a bit below the top of the black paint.

puget-sound-naval-shipyard-wash-march-12018-psns-imf-on-the-waterfront-personnel-bring-uss-nim...jpg

As the ship comes in, the shipwright on the platform here is sighting on that target and calling the position of the ship over the radio so the linehandlers and tugs can adjust to keep her in position. Same thing is done for landing on the blocks.
Capture.JPG


Setting up to undock. You can see the benchmark under the tripod and tape measure being used for either an offset measurement or to help point to the marks on the benchmark
200406-N-IV689-0002.jpg
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Aaron Z
 
plym49.2 said:
Wonderful! I love learning about the details of different processes. I imagine that nowadays there is GPS supplementation as well.
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Not accurate enough for landing, but might be a useful aid for SA. One of the other yards had a system that provided electronic position data, but I was never clear if it was GPS or laser based, and never saw it personally. As with many things, it's only as good as the accuracy of the setup, and it's less useful in practice than you'd think. I don't want people with their heads glued to a computer screen, but rather want them paying attention to what's going on.

At least some of our floating docks do use a computer system, but they operate differently. On these docks there are 2 pairs of trolleies run along each side of the top of the wing wall with winches on each trolley. When ships are brought in, the winch lines are connected to cleats across from each other on the ship, the winches are used to tension the lines and then moving the trollies brings the ship into dock. One set fwd and one aft provides control of the ship while pumping down. These are operated using computer systems since you can determine ship position from the winch cable and trolley position. Also computer control of the pumping systems as pumping a floating drydock is complex - the pumping of individual tanks needs to be sequenced properly so the buoyancy in a specific section is equal to the load on it. Ships are not a uniform load, and the dock is not strong enough to tolerate much imbalance. This is usually what causes floating docks to break in half or other wise fail.
 
aczlan said:
To get around line of sight issues perhaps, but beyond that a standard laser "total station" would be sufficient, IIRC from earlier in the thread they have benchmarks around the dock and can calculate the angle/distance from any of those to any of the blocks. The earlier post:


Aaron Z
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Not measuring distance/angle, rather using the transit to establish a line and visually measuring the lateral distance between the transit cross hairs and the reference mark. Stupid simple and reliable. The target on the boat generally has known dimensions and in many cases a ruler, so the operator looking the a transit can simple look at the ruler and see where the crosshairs line up. Hard to see clearly, but target is circled in the picture.
 

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sdmuleman said:
Not accurate enough for landing,
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A random standalone GPS receiver isn't accurate enough for much other than navigation but a calibrated base station on the drydock plus a receiver on the ship (basically the same setup you see used in construction, mining and farming) should be accurate enough. I don't think ships are coming and going from drydock often enough for it to be worth the hassle. It's not like a pit mine where you have dozens of machines that can utilize the system all day every day so I can see it not penciling out.
 
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sdmuleman said:
Not measuring distance/angle, rather using the transit to establish a line and visually measuring the lateral distance between the transit cross hairs and the reference mark. Stupid simple and reliable. The target on the boat generally has known dimensions and in many cases a ruler, so the operator looking the a transit can simple look at the ruler and see where the crosshairs line up. Hard to see clearly, but target is circled in the picture.
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Interesting, so the transit is "fixed" on a known bearing from a particular benchmark and they use that with a target to get from within a couple inches to within an couple of 8ths.

I am surprised that they don't use a target and laser total station, but I suppose once you have the bearing locked with a transit in you don't need much more.
I learned the other day that they use a target and a laser total station to measure distance for some tractor pulls:


arse_sidewards said:
A random standalone GPS receiver isn't accurate enough for much other than navigation but a calibrated base station on the drydock plus a receiver on the ship (basically the same setup you see used in construction, mining and farming) should be accurate enough. I don't think ships are coming and going from drydock often enough for it to be worth the hassle. It's not like a pit mine where you have dozens of machines that can utilize the system all day every day so I can see it not penciling out.
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Otherwise known as Differential GPS: Differential GPS - Wikipedia
It would likely be possible to put a pair of receivers in known locations at the bow and stern of a ship when its being brought in and feed those locations into the computer that controls the trolleys and winches to allow it to track the ship location.


Aaron Z
 
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