Large Drydock in 1942

No one ever said a dry dock had to hold only one ship at a time.

Now I'm no expert on dry docks, but... I'm an architect. The parallel with buildings that stay dry is this. It costs just as much to bake a loaf of bread with 30 slices as it does one with 48. The baker makes the same per hour, the bag costs the same, the oven costs the same, the truck costs.. well you get the idea.

In a building, roughly speaking, you spend fixed costs on mobilization to build it, the site, the plans, the engineering and so on within a given envelope of factors.

I would guess that no one ever built a smaller dry dock than they had room for. The gate at the end is expensive and costs a fixed amount, the four corners cost the same, the pumps ditto; all the extra cost is land, which is cheap in a situation like that, and straight runs of concrete wall, which are cheap too under the bread model.

So, when someone sets out to build a drydock, they pick a place to do it and make the biggest one that'll fit, I would assume.

I'm not familiar with this dock, but many large dry docks had a second set of doors part way along their length so multiple vessels could use it simultaneously.

tucchase

I didn't want to hijack the Ship's Quiz thread so I am starting a new one. A question was raised about a large unused drydock and one answer thought it might be Drydock #8 in Norfolk, but since that is used for the Nimitz Class carriers, that disqualified it as being not unused.  I queried whether a drydock might have been built with the Montana's in mind, but never used because the Montana's were canceled just before the keel of the Montana was laid.  Subfixer replied that #8 is the biggest he knows of in this country and it is used for the Nimitz's, but they are 200 feet longer than the BBs. 

  I stated that the dry dock at Newport News Shipbuilding and Dry Dock Company (Northrop Grumman) is the largest one in the US that I know of. Just to keep the record straight.

 

 

Yes, but ships are not maintained on shipways, so if they had been built, they would have had to be maintained somewhere, and it sounds like Norfolk #8 may have been intended for them, or something equally as large.  It was built in 1942, long before the Montanas were stopped.  And if they had built the Montana to Design Scheme #8, it was probably the only drydock capable of fitting it in.  Do you know of any other ship being planned back then that would have required a drydock of well over 1000 feet?  The Nimitz Class carriers weren't even a gleam in anybody's eyes back then.  They weren't even planning the Forrestal yet.  But someone evidently figured there was an immediate need, or would be a need for a drydock that big.  Else why build it in 1942?  Anybody have any ideas why a drydock this big was built in 1942 when the longest ship we had was probably the Iowa Class at just under 900 feet?

The Navy routinely places more than one ship in dry dock at a time, as conditions permit. Remember the Pennsylvania, Cassin and Downes were all in dry dock #1 at Pearl Harbor during the attack, although  the dock wasn't sectioned off in two.  Dry dock #2 at Pearl Harbor Naval Shipyard is still configured to be sectioned off and has a spare caisson for that purpose. It's the only one of the US Navy's dry dock that still has that capacity that I know of. Dry dock #4 at Norfolk used to have that feature but not any longer.

Also, there have been many naval shipyards that have been closed down over the years. I don't know how big the dry docks at Philadelphia, Brooklyn, Long Beach or Hunter's Point, S.F. were, They used to be major shipyards and could have had big ones there, too.

Looking at the specs in Table 1 of the link Subfixer put in Ship's Quiz, there are three drydocks large enough to handle CVNs, or the Design Scheme #8 Montana.  They are Norfolk #8, Pearl Harbor #4, and Puget Sound #6.  Puget Sound is the largest at 1151 feet (and 180 feet wide).  Then Norfolk, then Pearl Harbor.  No other drydock in this table would fit a #8 Montana.  Norfolk completed 1942, Pearl Harbor completed 1943, and Puget Sound completed 1962.  None of these three have secondary Caissons for seperate compartments, but they could all handle multiple ships.  Especially Norfolk and Pearl in WWII with the smaller ships back then.  To me, that could be a good enough reason to build them that big, but I have a feeling that just in case the Montanas were built, they wanted to be able to work on them.  In '42 they were still planning to build them.  Just a thought.

Sounds to me like you have an archival research project!   :: toast ::

Tracy White

Sounds to me like you have an archival research project!   :: toast ::

Oh, how I wish I could go to Washington DC, and Pearl Harbor, and Norfolk, and Puget Sound, and probably a dozen other places, and spend the rest of my life browsing to see what pieces to the puzzle I could put together.  On this subject, and probably a thousand others.  I love research.  Alas, lack of health, and a large lack of financing, prevent me from doing so.  Plus, my wife and I take care of my 84 year old Dad, which is pretty much full time nowdays.  It's why I retired early, so I could be at home full time.  And Retirement pay doesn't go far.  Getting, and building, the 1/200 Arizona is going to put a dent in my piggybank.  But there is no option there.  I have to have that model in order to build the most perfect Arizona that I can possibly do.  Yes, I could scratch-build, and I would probably be better off with all the techniques I would learn, but doing the 1/200 Trumpeter is going to push the envelope for me quite a bit. 

It just struck me as odd that they built these oversized Drydocks in 1942-43 when there were no ships that would require them at that time, and the only ones I know of that were planned to be that big were the Montanas.  Unless someone planned to use them for multiple ships at the same time.  PS #6 wasn't built until 1962.  PH #2, #3, & #4 were completed in 1941, 42, 43, respectively.  PH #2 is 1000 ft, and will hold a ship 990 ft long.  PH #3 is short. It's only 497 ft long, for a ship length of 482 ft.  PH #4 is 1088 ft, with a ship length od 1074 ft.  PH #2 will hold an Iowa Class, or any carrier at that time, or multiple ships as it also had a seperate Caisson in the middle to split the dock into two smaller drydocks.  PH #4 did not have a middle Caisson.

It was mentioned in one of the posts that that it would have been relatively simple to make a longer drydock, as opposed to a shorter one, because you would only need more real estate, since the Caisson would be the same and the corners would be the same.  After looking at the drawings on the link Subfixer provided, I believe I will have to beg to differ in that opinion.  The three newer drydocks at Pearl harbor illustrate this point.  All of these drydocks have full reinforced concrete flooring under them, as well as full reinforced concrete sides and end.  PH #3 is the smallest.  It has a floor thickness of 11ft 6 in.  And a wall thickness of 12 ft 6 in.  PH #2 has a floor thickness of 17 ft 6 in, and walls of 20 ft thick.  PH #4 has a floor 19 ft thick, and walls 29 ft 6 in thick.  So with the corresponding thicknesses, PH #4 has an order of magnitude more concrete, rebar, Caisson size, and everything else, than even PH #2, which is only slightly smaller than PH #4.  These had to be planned meticulously and built accordingly.  Ph #2 was completed in 1941, so it was obviously started sometime before that.  The Iowa's were started in 1939 or 1940 weren't they?  So it makes sense that Pearl Harbor needed a drydock to handle them.  Norfolk already had #4 drydock which was large enough for an Iowa.  The Montana's were starting to be planned in 1940, and not canceled until July 1943.  So it would make sense also that the Navy would want to have a drydock on each major ocean to work on them when needed.  Hence Norfolk #8 and Pearl Harbor #4, completed in 1942 & 43 respectively.  Also, knowing that, if the Montana's were canceled, they would still be useful for multiple ships at one time, or some future larger ship, would allow the Navy to justify going ahead and building them.

Anyway, it is just some food for thought as to all the different planning that went into all the new ships that were planned before and during WWII.  I believe, that back then, it occured to someone, "OK, we are planning this ship to go toe-to-toe with the Yamato, and survive.  So where are we going to fix it when it does its job?"

Now, it is also important to consider that a dry dock also requires some physical plant of pumps and the like, and also generally requires some sort of provision cranes.  The capacity of cranes can be limited if they are to be traveling cranes, too.  So, the dimensions and uses combine.

Also, land space in a give port facility can be very limited, even if nothing appears to be there.  There are lines for utilities, fuel lines, storage tanks, all sorts of things.  In addition, you need rail access to much of your naval yard, and you need to limit curves (and curve radii) to be able to use the largest-capacity rail cars as well.

But, one factor in not building super-sized shore-based dry docks was in the efficiency of using sectional floating dry docks.   Unused sections can be stored elsewhere.  Also, fractional assemblies can be made up and stored in that state.  Most importantly, floating dry docks can be brought to forward operating areas, which has all sorts of advantages.

Its appears that the US Navy has disposed of  almost everyone of its floating drydocks. I guess the required manning and maintenance aren't cost effective. It is more effective to utilize private shipyards for the majority of dry dock required maintenance. Most USN owned dry dock usage is for nuclear powered ships

CapnMac82

Now, it is also important to consider that a dry dock also requires some physical plant of pumps and the like, and also generally requires some sort of provision cranes.  The capacity of cranes can be limited if they are to be traveling cranes, too.  So, the dimensions and uses combine.

The document in the link provided by Subfixer has complete listings of all the equipment used by each Drydock, including the pumps and cranes and captstans.  Plus all of the service capacities at each Drydock such as electrical, fresh water, saltwater, fire suppression, sewer, and compressed air.  In comparing the two larger Drydocks at Pearl Harbor for just their pumps:

Dewatering Pumps:  PH #2 - Four 52", 1,250 hp, 520,000 gpm.  PH #4 - Four 63", 1,250 hp, 663,000 gpm.

PH #2 is only a little shorter and narrower, but its pumps are much smaller.  I would imagine those larger pumps were a lot more expensive too.  Due to the volume of water that must be pumped, even with the larger pump capacity PH #4 takes 190 minutes to drain versus 140 for PH #2.  Refilling is faster at 120 minutes and 90 minutes, respectively.  The chart doesn't say, but I am presuming that these times are given to empty or fill a drydock sans ship.  I would imagine PH #4 would drain a lot faster if most of its volume was occupied by the Nimitz!  Do any of you know if this is indeed the case?  Three hours would be a long time to wait for the water to be gone so crews could start work on the hull.  I am sure they would be kept busy in any case though.

The pump times are for a dry dock sans ship.

As a radiation monitor, I was usually the first in the dock after pumpdown on a nuclear powered ship and got first dibs on the stranded fish. (Followed quickly by the riggers, who own the dock)

We still have a couple of floating drydocks at dogpatch/ south mooring. I can see them from my seats at the ballpark. Currently they've got the larger passenger ships in them.

subfixer

The pump times are for a dry dock sans ship.

As a radiation monitor, I was usually the first in the dock after pumpdown on a nuclear powered ship and got first dibs on the stranded fish. (Followed quickly by the riggers, who own the dock)

COOL!!

subfixer

Its appears that the US Navy has disposed of  almost everyone of its floating drydocks. I guess the required manning and maintenance aren't cost effective. It is more effective to utilize private shipyards for the majority of dry dock required maintenance. Most USN owned dry dock usage is for nuclear powered ships

It would be interesting to see how many of the private yards bought up the sectional floating docks.  I want to remember that's what they used on the last refit of BB-35.  Some Houston newsie asked the yard PIO if they were worried about their floating dock had the capacity to lift a BB.  I remember the PIO double-clutching (probably wanted something shiny to distract the newsie) before reiterating the lift capacities.

Were some cool photos, Texas up in the dock sections, open at either end to show off the torpedo proyection added.

tucchase

The document in the link provided by Subfixer has complete listings of all the equipment used by each Drydock, including the pumps and cranes and captstans.  Plus all of the service capacities at each Drydock such as electrical, fresh water, saltwater, fire suppression, sewer, and compressed air.  In comparing the two larger Drydocks at Pearl Harbor for just their pumps:

Well, to be very specific, one thing I was wanting to bring up, which is that, while the site plan of a given harbor might seem to have large unused areas, it can be that those areas are less-useful.

And, the geometries are complicated.  Far the largest docks, you need a straight shot from a deep-water channel.  You need some maneuvering room to operate tugs in.  If the dock uses a floating caisson, your entry basin needs room for the tug that has a hold of that as well.

The other factor in building a dry dock is in it's construction.  You are digging a big giant hole next to the ocean.  So, your construction site needs some room for materials storage, for the access  for the equipment that built the cofferdam, and an area for where you off-load the spoil from the hole (not all of which may be leaving that site, or the port itself).

Thank you CapnMac82.  This emphasizes even more the point I was trying to make that making these large drydocks was not just something thrown together willy-nilly.  They took a LOT of planning and a LOT of labor to make these beasts, so, unless the need and the requirements were very great, these would not have been made. They could have made smaller ones for less work and cost and still met the needs of the Navy at that time.  But someone thought there would be a need for a drydock capable of servicing a ship with a length of over 1000 feet.  Remember, Pearl and Norfolk already had drydocks capable of handling up to 1000 feet, but not in the 1050 to near 1100 foot range.  As far as I know, there was only one class of ship being planned at that time that would need these drydocks.  That is the Montana Class as envisioned in Design Scheme #8.  Which leads me to believe that this scheme was the one that would have been built if they had continued with them, since the other schemes would have fit in the other drydocks that were already there.  If I have the chance to build a Montana, I will build it to Scheme #8.  If I get real ambitious, I'll even see if I can put it in PH #4!

Here's an aerial view of the Norfolk Navy Yard:

Dry dock #8 is sthe one at the lower left, DD #4 is at the middle, and DD #1 is at the right. The best view is by using Google Maps, locate Portsmouth, Virginia and work your way down the waterfront.

I am going to make an attempt to give you a link to a Google Map of the area. The adress to put in the search box is:  (Copy the address and paste it in the box) 

1 Norfolk Naval Shipyard Portsmouth, VA 23709-1001

Thanks Subfixer!  That's pretty cool!  I've used Microsoft Live Maps also.   I just looked at Live and there are two CVNs in port next to DD#8 at Norfolk.  Live also has what they call "Bird's Eye View", which shows even closer than the satelite photo. Plus you can view the same location form the orientation of each compass point., NWSE.  In the Bird's Eye View of Norfolk DD#8, CVN-73 in in dock, in 2 views from South & North.  East  & West Views show a Helicopter Assault Carrier #1 in the dock. In panning left and right from the South View the picture would change occasionally from the CVN-73 to the Assault Carrier #1.  Panning North CVN-69 was at dock two slips North of DD#8.  In the Satelite photo there are two CVNs in the two slips immediately North of DD#8.  One is CVN-71, but the other one has a canopy covering the entire foredeck, so the number can't be seen, but it is identical configuration of CVN-71.  This Bird's Eye View is pretty neat.  It gives you closer pictures and from each side if they filmed each direction at about the same time. Here is the link for Live  Maps. 

http://www.bing.com/maps/

 That's a nice angle. That picture was taken on a weekend because of the availability of parking spaces, and a it was taken over two years ago because there hasn't been two CVNs at NNSY inat least that long.

The Google one is newer because I checked my neighborhood for clues. It is nice being able to have access to this stuff, isn't it?

subfixer

 That's a nice angle. That picture was taken on a weekend because of the availability of parking spaces, and a it was taken over two years ago because there hasn't been two CVNs at NNSY inat least that long.

The Google one is newer because I checked my neighborhood for clues. It is nice being able to have access to this stuff, isn't it?

Yes, it really is.  In fact, the amount of information we have available now on the internet is just flat awesome!  This is absolutely the best time to be a modeler.  The number of kits available is the most there has ever been, with more rolling out of the pipelines almost daily.  The aftermarket upgrades are fantastic.  But most of all, the information that is available to be able to make your model any version you want is incredible!

subfixer

 That's a nice angle. That picture was taken on a weekend because of the availability of parking spaces, and a it was taken over two years ago because there hasn't been two CVNs at NNSY inat least that long.

The Google one is newer because I checked my neighborhood for clues. It is nice being able to have access to this stuff, isn't it?

I was looking at the Bing Map again and I noticed on the Satelite picture that apparently there had been a third CVN that had just left DD#8, or maybe one of the other two had been in DD#8 before its present location in the Satelite pic.  Many of the keel blocks are still in place.  Most of the bow blocks have been moved, but there is still an image of the bow on the concrete floor.  Pretty cool!

Also, on the Bird's Eye View from the East on Bing Maps it shows CVN-69 in the second slip North of DD#8, and DD#8 has LHS-1 in it.  I noticed that the crane track area at the inland end of DD#8 has been torn out and a lot of work is being done in that area.  That should pretty much date when this pic was taken.  The Bird's Eye View showing CVN-73 in DD#8 shows this area as very clean and new looking.

I found out some more information on Norfolk Dry-Dock #8.  Also about other large dry-docks of the same, or similar, deminsions.  While I was just speculating as to why these dry-docks were made so large, it turns out I wasn't far off!  Apparently it was made for the Montanas, along with two in Philadelphia and possibly one in New York.  These were not just for maintenance though.  They were actually built as someplace to construct the Montanas as well as maintain them.  Here is a link to where I found this information, and an excerpt showing what I am talking about.

This entire article is about all the new construction being planned and built prior to, and during the early years of WWII.

The new expansion program included five battleships of the Montana class, with a London Treaty displacement of nearly 70,000 tons. These ships, whose dimensions were predicated on the availability of the third set of Panama Canal locks, had a beam greater than the clear space between the crane supports of the existing shipways. It was necessary to provide either new shipways or shipbuilding drydocks. The latter were selected; first, to avoid the problems and hazards involved in launching ships of such unprecedented size, and, second, to gain the advantages in ease of access, facility of construction, and simplification of weight-handling operations inherent in the use of drydocks. Construction was begun on the first two superdocks, at Norfolk and Philadelphia, in June 1940.

--174--

Why trivia games are cool! Just sets off more research!

bondoman

Why trivia games are cool! Just sets off more research!

YEAH!!

Which brings to light the reason why aircraft carriers are built to the sizes they are and not any bigger; they have to fit our existing drydocks. Although Dry Dock #8 has been modified in the last couple of years to accomodate CVN-77's ( USS Gerald Ford ) bulbous bow when it comes in for maintenance.

Oh I thought that was because the Admiral always trips and falls down the stairs.

subfixer

Which brings to light the reason why aircraft carriers are built to the sizes they are and not any bigger; they have to fit our existing drydocks. Although Dry Dock #8 has been modified in the last couple of years to accomodate CVN-77's ( USS Gerald Ford ) bulbous bow when it comes in for maintenance.

Is this why it was being worked on in one of the aerial photos on Bing Maps (as mentioned above)?  Were they extending it a little and had to re-route the crane tracks?  Inquiring minds need to know!

Yes, that was the reason. It took almost as long to do that little modification as to build the thing in the first place.

Yes there are very large dry docks yet their scope & size may be a daunting task to model.

Here is a picture of a smaller version that uses rails & the high tide to achieve the same results for smaller vessels: