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  • #61
    Looks like elephanitis of the bow!
    Covid 19 is not over ....it's still very real..Hand Hygiene, Social Distancing and Masks.. keep safe

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    • #62
      Originally posted by hptmurphy View Post
      Looks like elephanitis of the bow!
      This type of bow helps to increase the speed of a ship. It looks strange but it works.

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      • #63
        Originally posted by Test Pilot View Post
        Is she sitting directly on the dock floor or is the bulbous bow lower than the keel?
        Neither, and both.
        The Keel is sitting about 8 foot off the dock floor. The Bulbous bow is in a tank below the level of the dock floor(see first photo)


        Catch-22 says they have a right to do anything we can't stop them from doing.

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        • #64
          I always thought the bulb held sonar equipment. furthest away from engine noise? :confused:
          "The Question is not: how far you will take this? The Question is do you possess the constitution to go as far as is needed?"

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          • #65
            Not always. It serves to keep the bow in the water on larger vessels, such as the latest design of US Amphib transports and Aircraft Carriers, and prevents much of the pounding experienced in heavy seas.


            Catch-22 says they have a right to do anything we can't stop them from doing.

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            • #66
              Bulbous Bow

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              • #67
                Isn't that bow called a wave-breaker? the ship lifts you mentioned are fine bits of kit.I saw one in a yard in Italy and it allowed excellent access to the hulls of basin tugs, whilst being comparatively small.There's one in Howth for the trawlers.
                regards
                GttC

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                • #68
                  Originally posted by ZULU View Post
                  I always thought the bulb held sonar equipment. furthest away from engine noise? :confused:
                  It could do! In this case it may or may not have acoustic equipment, but there would be one major advantage of having a 360 degree sonar mounted here. It would be lower than the boundry layer, which is where a layer of air bubbles travel along the hull in some sea states and causes interference or noise. The bane of all asdic operators! As Zulu correctly said, keeping furthest away from engine or generator noise is another consideration in the design. If the 'bulb' was eight feet below the keel there would be a greater chance of a view to the stern, as the turbulence from the prop would be another issue to contend with. Also, the tilt could be raised to see further away towards the stern.
                  I can remember quite clearly listening to the engines and generators with the sonar trained directly aft, on the Eithne. Her Sonar was a Plessey make and was designed originally for helicopter use. It was known as a 'dunker', whereby the sonar head was lowered in to the water from a chopper and then raised and lowered in another area, so as to confuse the 'enemy' and to cover a larger search area. She used the 'Doppler effect' to determine range and was simply modified for ship use.

                  Attached is a photo of the operators console.

                  The top dial showed the direction of the sonar face in relation to the ship and a gyro heading. The two lower screens indicated strobe range and bearing of the targets.

                  This equipment was removed a few years ago from the Eithne while on refit and dumped in Cork dockyard. I stumbled across it once while in the yard. Shame! I spent a lot of time on this equipment!
                  Attached Files
                  Last edited by Test Pilot; 25 May 2007, 21:04.

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                  • #69
                    I knew it!!



                    Sensors: 996 Plessey surveillance radar; two 911 Marconi Seawolf trackers; BAE GPEQD; 2031E towed array sonar; 2050 bow sonar; UAT ESM system; and 1007 Kelvin Hughes and 1008 RACAL-DECCA navigational radars



                    "The Question is not: how far you will take this? The Question is do you possess the constitution to go as far as is needed?"

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                    • #70
                      Originally posted by Test Pilot View Post
                      It would be lower than the boundry layer, which is where a layer of air bubbles travel along the hull in some sea states and causes interference or noise. The bane of all asdic operators!
                      I remember reading a Tom Clancy Book (I know fictional but uses a lot of current fact)about how the US had a frigate using this bubble layer to hide its signature from enemy subs. THe bubbles would emit from a band across the keel. Any fact about this one?
                      "The Question is not: how far you will take this? The Question is do you possess the constitution to go as far as is needed?"

                      Comment


                      • #71
                        Originally posted by ZULU View Post
                        I remember reading a Tom Clancy Book (I know fictional but uses a lot of current fact)about how the US had a frigate using this bubble layer to hide its signature from enemy subs. THe bubbles would emit from a band across the keel. Any fact about this one?
                        Zulu, It's a breath of fresh air to talk to a like minded being! We must be on the same planet! (Hold it Moggy - don't jump in with the name Zog).

                        Yes, I would agree. If air bubbles distort what one see's below the water, why not use them to hide some of the details of your own vessel.

                        Other factors that distort information below water are temperature layers. If a 'ping' is directed to a target, and it passes through different temperature layers, the return signal or 'picture' is deflected. This can place the actual target in another place, where it may not be. A solution to this, is to drop a 'Bathythermograph' or sensor in to the water, which would pass data back to the sonar equipment to correct any errors from the target position. The 'Bathy' has a shape similar to a morter shell, and would decend at a known speed through the temperature layers to the bottom. It also has a temperature sensor fitted to record the varing temperature to allow the sonar to correct the target deflections, in its software.

                        What was not generally known, is that the Eithne had a launch tube in the hull, aft for this device. Long removed now!
                        Last edited by Test Pilot; 25 May 2007, 21:39.

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                        • #72
                          Hehe. Remember the one ( Debt of Honour I think) where he talks about the US Sub lauching a fish to wait below the thermocline before ramming straight vertical up into the Japanese Destroyer. Must go back reading those books.

                          Anyway keeping back on topic

                          Whats the biggest drydock we have in Ireland (Republic)
                          "The Question is not: how far you will take this? The Question is do you possess the constitution to go as far as is needed?"

                          Comment


                          • #73
                            Originally posted by ZULU View Post
                            Must go back reading those books.
                            I wouldn't.


                            The Bear and the Dragon reviewed by Brian Hook

                            The book is "The Bear and the Dragon". It is the story of China, which is led by psychotic brain-damaged panda bears, and the United States, which is led by Jesus Reagan (his name is actually Jack Ryan, but it's more fun to think of him as Jesus Reagan, since that's who he's modeled after). Russia's also in it, but only to serve as the "good foreigners" that get attacked, giving the USA moral justification to kill ****ing everyone and his brother.

                            Here's the loose plot summary.

                            Russia discovers it has the world's largest oil reserves and gold mine on the same day. This is the most realistic event in the book.

                            China's leaders, who to a one are all 60+ year-old perverts with acute brain damage, are plotting to invade Russia to take these valuable reserves. This is their latest of genius plots, the previous ones being getting Japan to go to war with the USA, and getting Iran and Iraq to team up and invade Saudi Arabia. I'm pretty certain that Destro or Major Bludd has influence with the Panda Council.

                            By the way, don't think about how the Chinese expected to get away with this. We're in the Clancyverse now, the laws of reason operate differently here......
                            Meh.

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                            • #74
                              I think 'prairie masker' is the name of bubble effect being talked about to deflect sonar ping.

                              en.wikipedia.org/wiki/Prairie-Masker
                              Last edited by hptmurphy; 25 May 2007, 22:50.
                              Covid 19 is not over ....it's still very real..Hand Hygiene, Social Distancing and Masks.. keep safe

                              Comment


                              • #75
                                Originally posted by ZULU View Post
                                Hehe. Remember the one ( Debt of Honour I think) where he talks about the US Sub lauching a fish to wait below the thermocline before ramming straight vertical up into the Japanese Destroyer. Must go back reading those books.

                                Anyway keeping back on topic

                                Whats the biggest drydock we have in Ireland (Republic)
                                Is it Dublin Port? It must be! the only dry docks are in Dublin, Cork and Belfast.

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