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Could a South Dakota Class BB do a Barn door stop?

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  • Could a South Dakota Class BB do a Barn door stop?

    The Sodak class has skegs on the outer shafts and I was wondering if that class could also do the "Barn Door Stop" maybe if they turned the rudders in the opposite direction than an Iowa facing out instead of in?

    A full crash back is almost a non-event. That's where all four screws are reversed from full ahead to full astern. It takes a little over a mile for the ship to come to a stop before going in reverse, but there is no feeling of inertia throwing you forward - unless you turn the rudders inboard toward each other to close off the passage of water between the twin keels. That is called a "Barn Door Stop" and only the Wisconsin has ever tested it. A former XO of Whisky said that when they threw a piece of wood over the side from the bow at the onset of that maneuver, the ship came to a stop with that wood no further aft than turret III. That's stopping a 57,000 ton ship traveling at 33 knots in about 600 feet, which means that anything that is not tied down winds up on deck or against a forward bulkhead.

  • #2
    I don't see why not, with the skeg configuration, lower gross tonnage, and lower top speed, it theoretically should stop even quicker. Just an opinion, no documentation.
    sigpic"If your plan is for one year, plant rice. If your plan is for ten years, plant trees.
    If your plan is for one hundred years, educate children."

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    • #3
      On the Iowa class, the skegs enclose shafts 2 & 3 which are the inboard shafts. The rudders are aft and just a bit off of centerline of the shafts. Therefore when a "barn door" stop was made, turning the rudders inboard nearly blocked the entire tunnel.

      On any ship that has two rudders, individually turning them either inward or outward will help slow a ship down rather quickly. But without closing off a tunnel as on the Iowas, they would act more like dive brakes on an airplane.

      It is a workable procedure but hull shape, rudder size, ship's speed, etc. would determine just how effective this is and is it worthwhile putting the rudder posts to extra strain.
      Able to leap tall tales in a single groan.

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      • #4
        Not to skew off topic here, but didn't this action cause some damage to the rudder shafts on the Wisconsin?
        "If a man does his best, what else is there?"
        -General George Patton Jr.

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        • #5
          Look what I found. Although it is about the Iowa class. The name looks familiar.

          Full Speed Ahead and Crash Stops on Iowa Battleships

          By Dick Landsgraff
          Updated 06 January 2000

          Well, I've been on a couple of sea trials where we cranked her up 10 rpm every ten minutes.

          That's EACH shaft increasing another 10 rpm. That's EACH 18-ton propeller increasing another 10 rpm.

          The skipper usually held out at a maximum of 200 rpm for the required 2-hour hold. However, the machinery was capable of kicking up another 10 or 15 rpm. But 31 to 32 knots was sufficient for the high-speed tests.

          When the ship got up to 26 knots, a rooster tail would start to appear. Vibration was reported, but only aft of frame 166 (where the aft transverse armored bulkhead is). Chief's quarters were pretty bouncy and the Nixie room was like standing on a jackhammer. I set my notebook down on a table to record some data and you can barely make out my handwriting.

          Walking forward, the vibration almost totally disappears as soon as you cross the threshold at frame 166. By the time you get up near the anchor windlass room, you can feel a slight torque to the bow. An almost imperceptible twisting that can only be felt by people with excellent sense of balance. I think it was that twisting that caused hairline cracks in the upper outboard corners of bulkhead 36 and allowed fuel to leak into the storeroom. Identical cracks were found on 3 of the 4 ships.

          Once the crew accidentally hosed me down when I stepped out onto the weather deck. They were washing down the teak and I was within range. But I just walked up to the bulwark on the bow, forward of the anchors, and let that 30+ knot headwind dry me off in a few minutes.

          The high speed turns can shake you up a bit. New Jersey was riding very light and heeled quite a bit. Missouri was ballasted a little better (plus having bilge keels in better shape) and heeling was almost unnoticeable.

          A full crash back is almost a non-event. That's where all four screws are reversed from full ahead to full astern. It takes a little over a mile for the ship to come to a stop before going in reverse, but there is no feeling of inertia throwing you forward - unless you turn the rudders inboard toward each other to close off the passage of water between the twin keels. That is called a "Barn Door Stop" and only the Wisconsin has ever tested it. A former XO of Whisky said that when they threw a piece of wood over the side from the bow at the onset of that maneuver, the ship came to a stop with that wood no further aft than turret III. That's stopping a 57,000 ton ship traveling at 33 knots in about 600 feet, which means that anything that is not tied down winds up on deck or against a forward bulkhead.

          Of the four BB's we reactivated in the 80's, the Wisconsin had the most problems with loose rudders. I wonder why. But Philadelphia did a great job of tightening them back up again.
          Full Speed Ahead and Crash Stops on Iowa Battleships

          I clicked the back button at the bottom of the article. Looks like alot of interesting reading on this web site.

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          • #6
            Originally posted by Ken_NJ View Post
            I clicked the back button at the bottom of the article. Looks like alot of interesting reading on this web site.
            That's the Warships1 board owned by Guy Derdall. That's where I met Grasshopper, cRusty and Razor.

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            • #7
              Originally posted by Ytlas View Post
              That's the Warships1 board owned by Guy Derdall. That's where I met Grasshopper, cRusty and Razor.
              WOW! I didn't know that Board was still around. I punched it up and took a look at my biography. I was only 62 years old then. In a few more days I'll be 74.
              Able to leap tall tales in a single groan.

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              • #8
                Originally posted by RustyBattleship View Post
                WOW! I didn't know that Board was still around. I punched it up and took a look at my biography. I was only 62 years old then. In a few more days I'll be 74.
                Really?

                You don't look a day over 72!!!!:))

                Greta sitem BTW.
                “Loyalty to country ALWAYS. Loyalty to government, when it deserves it.”
                Mark Twain

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                • #9
                  Originally posted by Michigan_Guy View Post
                  Not to skew off topic here, but didn't this action cause some damage to the rudder shafts on the Wisconsin?
                  As I understand Rusty's explaination, it can do some minor damage, but if the ship were in danger of a collision or a torpedo strike, it sounds like it would be a lesser evil. ;)

                  I wonder if this could actually be done quickly enough to be useful in such a situation, or if it takes some time to prepare to do it - like changing some hydraulics lines. Since the rudders on the SoDak wouldn't block the space between the skegs as effectively, it might be a little easier on her rudder posts.
                  sigpic"If your plan is for one year, plant rice. If your plan is for ten years, plant trees.
                  If your plan is for one hundred years, educate children."

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                  • #10
                    Originally posted by USSWisconsin View Post
                    As I understand Rusty's explaination, it can do some minor damage, but if the ship were in danger of a collision or a torpedo strike, it sounds like it would be a lesser evil. ;)

                    I wonder if this could actually be done quickly enough to be useful in such a situation, or if it takes some time to prepare to do it - like changing some hydraulics lines. Since the rudders on the SoDak wouldn't block the space between the skegs as effectively, it might be a little easier on her rudder posts.
                    You are quite correct in that. While working aboard some smaller twin-ruddered ships, I have overheard conversations of the crew and/or officers of practicing this "ultra" full crash-back manuever. But only at low speed for training of the crew.

                    It's merely a procedure of dis-engaging primary and secondary controls (the helmsman's wheels) and giving orders to local controls (the crew men in the rudder steering rooms) as to which way to turn the rudders.

                    As for occasions where this type of stop were needed, they would be rare but not impossible such as another ship coming out of a fog bank, surfacing of a submarine in front of you, etc. But this would only be workable if you knew in advance that such a collison course is highly suspect and bridge control has already put local control crewmen in the steering gear rooms with their hands on the hydraulic rams (or reverse switches on motor-driven gears) ready to move quickly upon receiving direct orders from the bridge.
                    Able to leap tall tales in a single groan.

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