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Thread: The Alaska's: Battlecruisers or Large Cruisers?

  1. #76
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    Their guns DID have a lot of problems. When the guns don't operate smoothly they certainly won't achieve there designed rate of fire. And yes turning radius in the post war world is a big deal. Subs were faster and deadlier in the post war years. The Iowas despite their size were very maneuverable. The Alaska's were beautiful ships but they can't really be considered a success. The Navy really didn't want them, they were forced on the Navy by Roosevelt.

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    This is what i've always known on the guns

    From NavWeaps:

    "These mounts had numerous problems, mainly because they had been rushed into design and construction without being properly tested.* BuOrd noted that "this turret is an outstanding example of a case where prior testing of a new design by the manufacture of a pilot model was required."* It appears that these problems were satisfactorily resolved in service, as former crewmembers have informed me that there were no major problems during their war-cruises."

    Also i know the turning radius was bad on them which factored into them not being able to evade a torpedo well unlike an Iowa which from what i've read could turn inside a DD. BUT what i was curious on was when they started making guided torpedos which would make her turning radius moot. Not sure on that so I guessed.

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    Quote Originally Posted by 85 gt kid View Post
    This is what i've always known on the guns

    From NavWeaps:

    "These mounts had numerous problems, mainly because they had been rushed into design and construction without being properly tested.* BuOrd noted that "this turret is an outstanding example of a case where prior testing of a new design by the manufacture of a pilot model was required."* It appears that these problems were satisfactorily resolved in service, as former crewmembers have informed me that there were no major problems during their war-cruises."

    Also i know the turning radius was bad on them which factored into them not being able to evade a torpedo well unlike an Iowa which from what i've read could turn inside a DD. BUT what i was curious on was when they started making guided torpedos which would make her turning radius moot. Not sure on that so I guessed.
    There are many other sources besides Navweaps that state there continued to be some problems with the mounts. Although modern torpedoes are almost impossible to evade, torpedoes in the immediate post war period into the 60's were not so advanced. The Belgrano was sunk by the RN in Falklands War using straight running torpedoes. With advanced detection there's at least a chance. Tactical turning radius is never moot in combat. The Alaskas couldn't turn for squat. Just out of curiosity, what is your military experience?

  4. #79
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    Amateur historian (would have joined the Navy if I could but I had a bone marrow transplant when I was a kid which shot that down). I wasn't sure on the torps which is why I asked.

    so no i'm no expert by any means just stating what i've read (sorry would have put this is in but i had just got up). Now off to Duke medical whoo
    Last edited by 85 gt kid; 31 Mar 14, at 12:03.

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    Quote Originally Posted by 85 gt kid View Post
    This is what i've always known on the guns

    From NavWeaps:

    "These mounts had numerous problems, mainly because they had been rushed into design and construction without being properly tested.* BuOrd noted that "this turret is an outstanding example of a case where prior testing of a new design by the manufacture of a pilot model was required."* It appears that these problems were satisfactorily resolved in service, as former crewmembers have informed me that there were no major problems during their war-cruises."

    Also i know the turning radius was bad on them which factored into them not being able to evade a torpedo well unlike an Iowa which from what i've read could turn inside a DD. BUT what i was curious on was when they started making guided torpedos which would make her turning radius moot. Not sure on that so I guessed.
    I'd like to know what you've read, because whatever it is, it's total bovine excrement. As agile as they were, and I rode both New Jersey and Missouri for inspections, and operated a frigate close aboard New Jersey, they could NOT turn inside a DD. Not now; not ever.

    Glancing at the starboard side plans for the Alaska, it is very obvious why she had a poor turning radius. She only had one rudder, mounted center line. That is indeed a recipe for poor performance in maneuvering as with four screws, the rudder was not mounted to make best use of their hydrodynamic capabilities in any way, shape or form. Unfortunately, it seems to be a lesson that we have to relearn from time-to-time. My third ship, USS Gridley (CG 21), which was a Leahy-class guided missile cruiser only had one rudder and she was a pig compared to my first ship, USS Constellation (CV 64), which had two rudders mounted aft of the two inboard screws. If the CO, and the airplanes, didn't mind, she had a reduced tactical diameter of about 800 yards. One of the Iowas would have been about the same, maybe a little less (say, 600 to 700 yards); but a DD has a reduced tactical diameter of around 400 yards. At the end of the day, it's the difference between being over 800 feet long, and being only 400 to 500 feet long, and where relatively speaking, that places the pivot point of the ship (generally just abaft the pilot house in most conventional ship designs).

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    This thread makes me miss my friend.... RIP Whiskey

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    Quote Originally Posted by desertswo View Post
    Unfortunately, it seems to be a lesson that we have to relearn from time-to-time. My third ship, USS Gridley (CG 21), which was a Leahy-class guided missile cruiser only had one rudder and she was a pig compared to my first ship, USS Constellation (CV 64), which had two rudders mounted aft of the two inboard screws. If the CO, and the airplanes, didn't mind, she had a reduced tactical diameter of about 800 yards. One of the Iowas would have been about the same, maybe a little less (say, 600 to 700 yards); but a DD has a reduced tactical diameter of around 400 yards. At the end of the day, it's the difference between being over 800 feet long, and being only 400 to 500 feet long, and where relatively speaking, that places the pivot point of the ship (generally just abaft the pilot house in most conventional ship designs).
    Does the destroyer turn radius of 400 yd take into account reversible/variable pitch screws?

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    I believe it was Malcolm Muirs book on the Iowas. If I remember correctly that came from a CO of one but you know how that goes. When I toured the Wisconsin again Saturday they told me she did 39 knots in the bay . I'll be back wednesday i think so i'll have someone dig the book out for me (getting a wicked awesome surgery on my ankle ).

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    Quote Originally Posted by 85 gt kid View Post
    I believe it was Malcolm Muirs book on the Iowas. If I remember correctly that came from a CO of one but you know how that goes. When I toured the Wisconsin again Saturday they told me she did 39 knots in the bay . I'll be back wednesday i think so i'll have someone dig the book out for me (getting a wicked awesome surgery on my ankle ).
    I have nothing but respect for the docents that volunteer at museums and their service to country. But more than once I've heard an old veteran or docent at a museum recount something that wasn't quite accurate. Sailors love sea stories, even sailors in the Coast Guard. I'm not saying that she didn't make 39 knots, since I'm not an "expert" on the Iowa class. But I'm smelling fish somewhere. I think I've read accounts of short runs up to 34 or 35 knots. I have the same book, I'll have to see if that's in there anywhere.

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    Quote Originally Posted by DonBelt View Post
    Does the destroyer turn radius of 400 yd take into account reversible/variable pitch screws?
    Interesting question. The short answer is "No," but it requires a little more information to understand that particular phenomenon in the modern era. You know, the CRP as mounted in the Spruance and Ticonderoga-class did not behave the way one would expect a backing screw to behave (I always recommend people go to their supermarket and drive a shopping cart . . . it's the best tool I know for demonstrating how various combinations of ahead, stopped, or backing bells actually work to maneuver a ship). In a word, they "didn't" work. That is, you couldn't put right rudder on, and back the starboard shaft, and expect a tight turn to the right. You will go to starboard, but it won't be any tighter than any other ship. Back the starboard engine on one of those Fletcher-class we all love, and you will pull that stern over to port in a nano-second, and the bow will swing accordingly. Why doesn't the CRP work the same way in the Sprucans and Ticos? Simple, the brainiacs who design things never ask the end users about such concepts so they do what's easy for design and space saving purposes, and in this case, they mounted the LM2500s and their respective reduction gear in just the opposite fashion from a traditional steam design such that when simply spinning, as the CRPs do with no pitch on, the starboard screw is rotating counterclockwise, and the port screw clockwise. This is again, just the opposite of a traditional steam ship in which the starboard screw spins clockwise in the ahead direction, and the port screw counterclockwise. That imparts what is known as a side force to the screws which causes the starboard to walk the stern to starboard in the ahead direction and the port to walk the stern to port. Of course, they cancel each other out, and all that is left is the ahead force that drives the ship through the water. Back that starboard engine though and it walks the stern to port. The side forces of both the starboard and port shaft are now additive in nature and the stern swings sharply to port. Again, the CRPs in the Spruance and Ticos were bassackwards and didn't work that way.

    However, in the Arleigh Burkes, they corrected that problem, the starboard screw now turns clockwise while just spinning, and the port counterclockwise, and the CRPs now work as expected. You shift the starboard screw astern and you will get some swing to port. Note that I said "some." That's because at the end of the day, the screw is still turning clockwise so there isn't the same sort of side force imparted to the stern as is found in a steam ship, but it IS better than it used to be, as evidenced in this very fine video of USS Gonzales doing a high speed turn at what I make to be better than 30 knots abreast one of the CVNs. Note the way she digs in while in that turn and really heels to starboard. I'm pretty sure the CO backed the port screw although it's hard to say for sure. It's still very tight.


  11. #86
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    Yea theres an article on Nav Weaps somewhere where a guy explains how fast they could go it's very interesting. He also did one on the nuke carriers too. I know NJ was reported of doing 35ish which apparently was true BUT it was a light load and in shallow water (apparently shallow water doesnt count, something to do with waves or something?). That turning radius was in either the Korea part or Vietname part I believe.

    Thanks for explaining that Desert very interesting!

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    Quote Originally Posted by 85 gt kid View Post
    Yea theres an article on Nav Weaps somewhere where a guy explains how fast they could go it's very interesting. He also did one on the nuke carriers too. I know NJ was reported of doing 35ish which apparently was true BUT it was a light load and in shallow water (apparently shallow water doesnt count, something to do with waves or something?). That turning radius was in either the Korea part or Vietname part I believe.

    Thanks for explaining that Desert very interesting!
    Shallow water should not result in faster speed. In fact, you set up a rather dangerous situation if the water is too shallow. When in close proximity to the bottom, the velocity of the water passing beneath the hull of the ship and the bottom creates a Bernoulli effect that causes the stern to squat pretty noticeably. I did this at the carrier pier in Pensacola on a frigate when I kicked it in the ass just off the pier with the stern facing the pier at a 90 degree angle. I gave everyone on the pier a shower, which was my intent (long story, good friends, and a little fun while ship driving) but I also squatted like a hound dog about to take a dump and came very close to dinging the screw on the bottom. Lesson learned. Anyway, one should always be mindful of speed in shallow passages as it can get you into trouble in more ways than one.

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    Whiskey ..

    Quote Originally Posted by zraver View Post
    This thread makes me miss my friend.... RIP Whiskey
    My sincere regards, I was not aware of this event.

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    Jason, my thoughts exactly.

    Really miss him AND Shamus.
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    I'm going to go out on a limb here and post Tony DiGiulian's article in its entirety.

    Speed Thrills II - Max Speed of the Iowa Class Battleships

    By Tony DiGiulian
    Updated 08 November 1999

    Since I did my original essay on "Fastest Battleships" awhile ago, I've heard at least twenty claims that the Iowa class battleships could achieve even higher speeds than what I have in the essay. In about ten of those cases, I've gone to the trouble of tracking down the supposed source of the claim. In every case that I've investigated, there either proved to be no such source, the book in question made no such claim, the person was conveniently not available, or (my personal favorite) someone mistook a mile-per-hour value for a NAUTICAL-mile-per-hour value (the Iowa's designed top speed of 32.5 knots is 37 MPH).

    In the hope of reducing the number of such claims that I get in the future, I decided to spend a little time determining:

    "How fast could the Iowa class battleships really go?"

    The Iowa's power/speed curves are reportedly classified and are not available for calculations of this nature. And, unfortunately, the two incidents that I am aware of where an Iowa class battleship made around 35 knots both occurred in relatively shallow water immediately following a refit. As such, the speeds and SHP attained are not really applicable to their deep water performance. So, I have had to fall back upon the results of the powered and unpowered model basin tests and calculations performed in the 1940s (deep sigh). Not nearly as satisfactory a source as I would like, but, still, perhaps illustrative enough of these ship's performance.

    There is some data on these tests and calculations available in several publications, including "US Battleships" by Friedman, "US Battleships 1935-1992" by Garzke and Dulin and "Iowa Class Battleships" by Sumrall. In addition, there are several speed/power/displacement figures given for these ships in these three particular publications. I have used this data in standard computations to derive predicted performance.

    From the model testing, the Navy calculated that at a Trial Displacement of 53,900 tons (which is about 2,000 tons less than their 1988 fit) a speed of 32.5 knots @ 212KSHP (Designed SHP) could be accomplished.

    The Iowa's were constructed so as to permit a "designed overload" of 20%. This means that they could generate 20% over their designed power rating of 212KSHP without fear of damaging the engines. Based upon this and the results of the model testing, the Navy theorized that a lightly loaded Iowa at 51,000 tons could reach 35.4 knots at 254KSHP (Please note: This is generally accepted as the maximum credible deep-water speed for these ships).

    Now, the Navy also estimated that every 1,000 tons less in displacement would give an additional 0.25 knots of speed. If I can "cheat" by saying that I've offloaded every last piece of unnecessary gear to reduce my displacement - after all, who needs those silly Harpoons, anyway? This is a big-gun battleship, not a DDG - then I can reduce those numbers a bit. The above mentioned reference sources have a good deal of equipment weight data which I have used for these estimates. Semi-reasonable offloads (my definition, I'm not going to cut away the foremast just yet) could reduce the displacement down to 48,900 tons (see the Appendix below for details). This is 5,000 tons less than Trial Displacement, which would imply a maximum speed of 33.75 knots @ 212KSHP. My calculations seem to show that this displacement would equate to about 36 knots @ 254KSHP.

    Now, could these ships go faster? If we accept that we might just damage those engines, then it seems plausible to me that 10% above the overload SHP figure would be attainable (Note: This is known as "forcing the engines" and is not recommended for those aspiring to the higher ranks). So, let's work with 280KSHP.

    A problem with this number is that it implies 70KSHP/prop. In the real world of 1940's prop design, this means that cavitation is going to happen in a big way. For that reason, I would guesstimate that 25% of this additional power is simply wasted in generating air bubbles around the blades. That being the case, then at a Trial Displacement of 53,900 tons, a tad over 34 knots would appear to be a top number. For a Light Ship Displacement of 51,000 tons, 36 knots would seem to be possible. However, there's another, real-world, problem with this much power. Even if the boilers could generate this much steam, trying to channel it into the engines may be a problem. The engines are probably not designed to handle these kinds of power inputs. Since I've never inspected the boiler/engine rooms myself (they were sealed on my one visit to the USS Wisconsin) nor have I been able to question the engineering people involved, I cannot make a judgment in this area.

    Are there other ways to get these ships to go faster? If you want to "cheat" even further, you can imagine that you give the bathers along the Delaware coast a real thrill and operate the speed trials much closer to shore than is customary in order to get a bottom effect advantage. You can also get a slight increase in speed if you fantasize that the Atlantic puts the proverbial millpond to shame on the day the trials are performed. I will leave those kinds of concepts in the misty world where they belong.


    Just for comparison purposes, I have dug up some of my notes on other nation's fast capital ships for which speed/SHP curves are not classified - as they both happen to be war losses. Namely, the German KM Scharnhorst and the British HMS Hood. The question is how much power would it take to drive these ships to 37 knots.

    Scharnhorst at a displacement of 38,950 metric tons (38,335 tons) (source: "German Capital Ships" by Whitley):

    10KSHP = 14 knots
    20KSHP = 18 knots
    40KSHP = 22 knots
    80KSHP = 26 knots
    160KSHP = 30 knots

    Note that every doubling of SHP translates into an additional 4 knots of speed. As a very simple analysis, if I simply use this factor and ignore the loss of efficiency from cavitation effects (as we're getting into the 60KSHP/prop range) and ignore the steeper hull resistance calculations needed for speeds above 30 knots, then this would imply that it would have taken 320KSHP for the Scharnhorst to make 34 knots and about 500KSHP for her to make 37 knots. Quite a force job there, if I may say so. In actuality, 31 knots was about the top end for these ships, as in real life you simply can't ignore physics (except in high school).

    OK, you say, but that's for a ship considerably shorter and weighing in at about 20K tons less than the Iowa. Fair enough, so, how about looking at a ship a little closer in size, like the mighty HMS Hood?

    Trials run in the 1920s at 44,600-45,000 tons (source: "AS: HMS Hood" by Roberts):

    8,735 SHP = 13.2 knots
    14,020 SHP = 15.8 knots
    24,720 SHP = 19.1 knots
    40,780 SHP = 22.0 knots
    69,010 SHP = 25.7 knots
    112,480 SHP = 28.4 knots
    150,220 SHP = 31.9 knots

    Note that it takes about a tripling of horsepower at 15.8 knots to add six knots but it only takes about a doubling of horsepower at 25.7 knots to add six knots. In fact, when plotting this via a curvefit program, the power required rises at a steady rate, but then suddenly drops off at the end. Interesting.

    Sorry for the wandering, it's the engineer in me. Getting back on track:

    Using these numbers as a basis, then it would imply (again, ignoring all the usual suspects) that if we could only get those feisty engine room chiefs to give us a miserly 250-300KSHP, then we could sip our sherry on the bridge with a 37 knot gale keeping away the sea gull droppings. Is that too much to ask of those Jolly Jack Tars and superior British engineering technology? Sorry, but in my inexpert opinion, I'm 'fraid that it is.


    Note: The forgoing was meant to be a very rough look at a serious subject and I've tried to keep the concepts and mathematics simple. In reality, a good deal of calculus and a great deal more time than I'm willing to spend is needed to do these speed/power calculations properly. My apologies if I have offended anyone's sense of propriety.

    And, as long as I'm at it, let me just say that I am not a nautical engineer. I am simply a fairly well-read amateur with reference books and calculator at hand. I cheerfully admit that my power numbers may be 10, 15 or even 20% off in either direction. If someone wants to perform a more rigorous mathematical study of this subject, then I would be happy to discuss publishing it here at our Technical Board.


    A Postscript:

    The Iowa's were unquestionably the fastest and quite possibly the most powerful battleships ever to put to sea. To argue whether these fine ships could make 33, 35 or even 37 knots doesn't really make that much of a difference, they could have run down - or run out of fuel - any other capital ship ever built - and quite a few of the fanciful ones, as well. And, having run them down, faced no worse than even odds in a one-on-one battle with them. As battleships go, the Iowa's were fairly close to an ideal.


    For further information, may I suggest a visit to the Warships1 website showing the current status of these ships:

    Status of the Iowas

    For a look at what the Iowa's could do today, please visit the United States' Naval Fire Support Association (USNFSA).

    USNFSA Website


    Appendix I:
    What were my "semi-reasonable" off-loads?

    The USS New Jersey's weight table of 1943 showed a Full Load Displacement of 58,132 tons. 45,155 tons of this is basic structure and is not subject to reduction per my definition. Offloading parts of the remainder:

    70% of fuel oil: 5,659 tons (in reality, this would not be practical)
    80% of munitions: 2,074 tons
    36% of crew: 104 tons (The Navy estimated 250 lbs. per crewman, incl. equipment)
    33% of Reserve Feed Water: 164 tons
    80% of all stores: 1,179 tons
    100% of aeronautics: 52 tons

    Total Reductions: 9,232 tons

    "Semi-reasonable" Light Ship Displacement: 48,900 tons

    Appendix II:
    Other maximum speeds achieved.

    1) When the Iowa and New Jersey attempted to run down the fleeing Japanese destroyer IJN Nowaki near Truk in February 1944, both ships reached 32.5 knots with the throttles wide open, according to the Iowa's pitometer log. With clean bottoms, they probably could have gone a bit over a knot faster. There is no mention of what was the SHP or the displacement on that day.

    2) During her Korean tour, the Iowa's Captain William Smedberg remembered getting his ship over 33 knots on at least one occasion. There is no mention of what was the SHP or the displacement on that day.

    3) Before her Vietnam deployment the New Jersey obtained 35.2 knots at 207 RPM during machinery trials. There is no mention of what was the SHP or the displacement on that day.

    4) In 1985 the Iowa slightly exceeded 32 knots at 205 RPM. There is no mention of what was the SHP or the displacement on that day.
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