Why Are The Battleship's Propellers All Different?
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- čas přidán 8. 04. 2024
- In this episode we're looking at the different types of propellers.
For our episode on the propellers:
• Doesn't The Navy Requi...
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The views and opinions expressed in this video are those of the content creator only and may not reflect the views and opinions of the Battleship New Jersey Museum & Memorial, the Home Port Alliance for the USS New Jersey, Inc., its staff, crew, or others. The research presented herein represents the most up-to-date scholarship available to us at the time of filming, but our understanding of the past is constantly evolving. This video is made for entertainment purposes only.
This dry docking is teaching us so much more about Battleship New Jersey in terms of how well she is coping with sitting in the Delaware River for 25 years. Modern coatings will help the ship reach its 100th birthday and then some more. Keep up the good work.
I wish the Texas crew would've done the same and give us a little more in depth look at what and why. Ryan and New Jersey crew are killing it with the coverage they are providing.
As someone who is a volunteer on a museum ship that is 117 years old, I can't stress enough the importance of protecting the hall. We've been lucky that the ship has been kept in such good shape, but it's quite obvious that her hull will need to be replaced, which is what is going to happen in a couple of years.
All of it? The whole thing?
Reminds me of the old myth (Greek or Roman) of an important wooden ship... It was preserved, but over time individual planks would rot, and need to be replaced... I guess paint or stain had not been invented yet... Did anyone know about teak? How about cedar?
So, after a long enough time, ALL the planks get replaced... The question then is, is this ship still original, or is it a replica?
Apologies for this being so long... I need sleep...
@daytona1073 I've heard of it. You're speaking of the Ship of Theseus Paradox. It's something that constantly goes through my mind while I'm doing work on my ship.
Wherever I can do non-invasive modifications to the ship, I will do so. Wherever I have to, I do the absolute minimum damage to the ship itself, even resorting to zip ties instead of screws when mounting new conduit or cabling as an electrician.
Recently I've been running a new ethernet cable, and I ran it through a rivet hole that I found, which will later be covered up by decking (the carpets and wood underneath were in very poor condition, unfortunately).
The good news in my particular ship's case is that the central part of the ship has been mostly kept dry, so much of the original wood and steel are still in place, including some of the fittings. Unfortunately, that was not the case and the outer areas where water was able to get in. The hole itself obviously there's not much we can do, but thankfully, it's been kept in decent condition, all things considered. We're also lucky that its new home is an actual historic dry dock, so we won't need to ever move it again, even if we need to drain it to do work on the hull.
@@TheEDFLegacywhich ship is 117 years old? Olympia?
You mentioned the maneuverability of the Iowa class. One of my uncles was signalman on Missouri. He told me on their shakedown cruise he was up on the signal bridge when the captain (a former cruiser captain) brought the ship up to flank speed and then ordered full left or right (I do not remember which) rudder. He said the bow lifted up; she leaned over, and entered the turn just like a PT Boat. Forty thousand tons turning on a dime!
Hot damn! Kind of reminding me of the Battleship movie perhaps there's more truth to it than I originally thought. 😳
Gee.
The Iowas could turn inside some of their escorting destroyers. There was at least one incident where a destroyer captain apparently didn't believe this and nearly caused a collision (I read about this many years ago, don't remember the details).
~58,000t at full load which makes it all the more impressive. Must've been something to see.
@@TheEDFLegacy If they tried the "anchor turn" thing from that movie, they'd just rip the anchor clean off by snapping the chain.
I was there on the 6th of April and can tell you that the pictures can't do justice to how imposing the screws and rudders are. It is shocking to say the least. After the tour I saw Ryan and had a chance to thank him personally for all his efforts towards the upkeep and preservation of this magnificent battleship.
Very cool. I envy you. Thanks for sharing your experience with us.
Thank you for thanking him. I wonder if he has boys.
For those who are curious, the reason for the vibration problems on the fast BBs was apparently due to unanticipated interactions between the propellers and the skegs. Each time one propeller blade passed behind the skeg, the reduction in water for it to bite into resulted in a brief reduction in the power generated, making it more pulsed than previous ships. As it turned out, at certain speeds, this series of pulses would match the resonant frequency of the propeller shafts, causing the whole things to start vibrating forward and aft with the pulses in the power. On North Carolina, during her initial speed trials, apparently, the inboard shafts were vibrating almost *two feet* fore-and-aft before the chief engineer aborted the run out of fear that it would rip either a thrust block or a reduction gear set loose from its mountings.
There really wasn't any perfect solution to this; any sort of screw would generate the same sort of power pulses, which would hit the resonant frequency at *some* speed. The final fix was to essentially select a set of screws that would hit the resonant frequency at a speed *not* in a range of common fleet speeds (either cruising or battle speeds), and then just avoid that speed as much as possible--either staying below it, or just powering through it as quick as you could until you got out of the problematic shaft RPM range.
Similar problematic vibrations, albeit with a very different cause, were also found in the Atlanta class light cruisers; on Atlanta herself, during the twelve-hour top speed run in sea trials, cans of paint stored in the ship's fantail area were apparently vibrated to destruction(!), so this wasn't unique to the fast battleships. (Apparently, SS Normandie, with a somewhat similar hull form to the US fast battleships, also suffered from similar resonant vibrations during her early years.)
Do you have a source for this information?
I’m reminded of the issue of vibration for an aircraft transitioning to supersonic speed. I wonder if the physics are in any way similar?
Thank you so much for writing this out. It makes sense.
@@jetdriver I don't have a convenient link to it at the moment (it's on my currently-bricked laptop's hard drive), but it's from the official report on Showboat's vibration issues from 1944 or thereabouts, as found via some digging with Google, combined with some information from Norman Friedman's US Battleships: An Illustrated Design History. (Specifically, the stuff about just avoiding the problematic speed ranges and about Atlanta's vibration issues are from Friedman; the rest is from the Navy report.) There's also a little of my own personal interpretation in there (exactly *why* the chief engineer called off the top speed runs--it wasn't recorded beyond "to avoid damaging the machinery," but that's pretty simple to figure out!), and trying to summarize and boil down the more technical language to something a little more digestible in a less-technical forum such as this.
I'll note that the report also said that the reason nobody had anticipated this as being a potential problem is that no previous US Navy ship had ever experienced *longitudinal* (i.e., fore-and-aft) resonant vibration of the propeller shafts before; all previous resonant vibrations had been either side-to-side or up-and-down (or some combination of those two). As a result, while the ship was designed to damp out *those* sorts of vibrations well, nobody had ever considered that there might be a need for something to damp out longitudinal vibrations. One solution that was at least tried (it's not clear if it became a permanent solution) was to install wood blocks as spacers between the shaft itself and the sensitive parts of the machinery, to act as shock absorbers/cushions much like the wood blocks in Jersey's keel blocks right now.
Good info, thank you! I recall reading about ‘North Carolina’’s issues that you described, years ago
In Navy parlance we just called them screws but It's always impressive seeing them out of the water. Only then do you realize how powerful these ships were compared to most civilian ships and what it takes to propel a ship this size to 30 plus knots. I served on a gearing class destroyer and she could do 35 knots if the captain wanted to open her up but that speed was expensive in terms of fuel consumption. You can go fast or you can go far but not both !
One of my favorite “screws” versus “propeller” stories supposedly happened to the Royal Air Force. During the interwar years and in the early years of World War II the RAF’s official name for a propeller was an “air screw.” The story goes that an RAF bomber command base ordered a replacement air screw for one of their planes. What arrived was a replacement air crew for the plane. The RAF looked at this and realized that was too easy a mistake to make and the designation “propeller” was made official.
I worked on reactor feed pumps on the USS Enterprise CVN 65 at Alameda in the early 1980's. One of the engine rooms had a sign that said ''Longest shaft, best screw''. I used to know the length of the shaft but forgot the details. I recall that an engineer onboard said that the propeller shaft wrapped up in torsion 3-1/4 turns between the gearbox and propeller when the ship was at flank speed. That's a lot. The engine room crew always refereed to them as screws.
because screws are what they are
I wonder how many RPMs the shafts spun, on USS Enterprise at full speed ?
@@EricLetourneau-xq2dc I heard 120 rpm max.
3-1/4 turns on a massive drive shaft like that is a lot of stored energy and an enormous stress. I don't have to tell that to anybody here. Whew.
@@EricLetourneau-xq2dc hopefully no answers that, max. shaft RPM was and still is classified.
Ohhhh the exact area I needed to see for my epic battleship build! Thank you so much Battleship New Jersey!
Honestly I love this comment, don't know if your talking about a physical scale model, or a virtual (gamer, programer, etc) scale model.
@@jpjh8844 I make artwork, it has functional 16" cannons .177 bbs happen to fit in case potatoes don't do it.😉 You can see the Sherman Tank stainless steel build shoot potatoes in completed artwork.
The ship is 36" I had to sacrifice the aft end for space but it can be seen.
@@Not.The.Avg.Smitty Well that's just awesome.
@@aaronvockley5448 thanks
@Not.The.Avg.Smitty Plot Twist: It's a 1:1 model, and you are secretly plotting to sink a deepwater navy. 😅 j/k
When Massachusetts ends up going into dry dock eventually, not that its planned right now at all, PLEASE visit her. That video would be an amazing comparison between the two.
I think it’s a given Ryan would help them with what he’s learned and visit the dry dock
I love Big Mamie
The Massachusetts was drydocked in 1998-1999. I doubt it'd go in again anytime soon.
@@dieselyeti probably not, but it's deck is a mess
@@dieselyeti that means they’re due within ten years or so - ideally sooner rather than later.
If I remember right they’d never dry docked her since her decommissioning and had significant hull issues that required major repairs. I’m sure they want to avoid a repeat of that.
Funnily enough, I was looking into this, Massachusetts BB-59 started with 4 bladed props on all her shafts, and ended her career with 5 bladed outboard props and 3-bladed inboard props. So yeah, a lot of changes
Now, just hold on a minute there.
I saw the drydock photos from her maintenance in 1999. I found that odd too, assuming she'd have 4 and 5 blade props.
I think Friedman's book on U.S.Battleships has an extensive discussion on on the various propeller combinations used to reduce vibrations on the fast battleships. A lot of trial and error testing and it was not consistent from ship to ship, even those in the same class. I think the Iowa's were consistent, and eventually the North Carolina's but the South Dakota's were all over.
When the USS-Brush DD-745 was in drydock, I noticed that the rudders were not directly behind the center of the two 14 foot propellers. They were inset about a foot. I looked at the prints and, sure enough, that was the way the rudders were designed. I was told that the shaft could be removed without disturbing the rudders if repairs were needed. The New Jersey may use the same design. When you get a chance, take a quick look.
Ryan as a Naval architect I agree with you that vibration issues occurred in the USS North Carolina but what you do not address is the cavitation issue which can result in vibration not to mention the loss of propulsive efficiency. The inboard props are operating in the wake of the outboard props. This means that the inboard props will see the onset of severe cavitation at relative slow speeds resulting in vibration and loss of efficiency. This condition is magnified as the vessel's speed increase. One solution, at the time of the ship's design was to increase the expanded area ratio of the propellor. This is accomplished by increasing the number of blades and reducing the diameter of the propellor. Before the advent of high speed computers propellor design was a black art governed by experimentation and trial and error as demonstrated by the year long sea trials of USS North Carolina.
I as a retired fitter would like you to give us a more blow by blow of the work as it is done.
Another ex fitter here, have great memories working in dock bottoms playing with huge props and falling over inside bow thruster tunnels
In re the centerline bulkhead.
In the early hours of 29 May 1914, the RMS Empress of Ireland was T-boned in St. Lawrence River outbound from Quebec City, QC. by the Norwegian collier Storstad near the town of Rimouski. The Empress had side by side propulsion spaces in a 4x4 arrangement. The Storstad hit her at the bulkhead dividing the stbd boiler room and the stbd engine room. Counter flooding was attempted but couldn't keep up with the inflow from the damage. The ship capsized just a little over 14 minutes after the initial collision. 1,012 of the 1,477 passengers and crew perished, most not having time to even get to the lifeboats. This shocked the naval architecture community and the centerline watertight bulkhead pretty much vanished.
Screws or props is what I referred to them when I was onboard the USS Indy CV-62 back in the late 70s.
I'd like to take a moment to stop and appreciate the joke at 6:10. The Hollings (or Holland) tunnel, the tunnel that has the most traffic of any tunnel in New Jersey.
I would love to go to see this beauty in dry dock but unfortunately living in the UK makes that very difficult
I am amazed at the amount of knowledge that Ryan has . I've been into warships my entire life and I thought I knew alot until I started watching Ryan's videos.
He has a 800’ library.
Or you could say, " He has a boatload of knowledge"... LOL
Yeah, it's 887 feet long, 108 feet wide and an inch deep
Ryan's office library is incredible. He allowed me to sit in his office and peruse some of the hundreds of books and documents.
He is an excellent educator and shares his ship enthusiastically. Get a private tour with him.
Ditto. I've been fascinated with this subject since I was about nine (I'm now in my 30s), and I still learn cool new shit every time I watch one of these videos.
The South Dakota-Class was built with all 4 bladed propellers, with Indiana swapping to 5 bladed outboards and 4 bladed inboards and Massachusetts swapping to 5 bladed outboards with 3 bladed inboards. Their propellers were almost completely lined up with each other but the inboard were slightly forward more, unlike the Iowas. Also unlike the Iowas the skegs are on the outboard shafts instead of the inboard.
The South Dakotas were designed different to the Iowas because they were a different design. Despite the design differences both ships could travel backwards if they reversed the rotation of their propellors.
If there were 5 frogmen around each outboard propeller, there would be 20 more fins in the water.
I don't know about the other SoDaks but the Massachusetts has 3 blade props inboard and 5 blades outboard.
@@dieselyeti Massachusetts was built with four 4 bladed props, but later changed to 5-blade outboard and 3-blade inboard.
I dont remember if the other SoDaks followed suite, but thanks for catching that.
Impressive to see how precisely the ship landed on its blocks.
Screws, of course. Back in the 80's on a destroyer we had a CO who had been Ops on an Iowa class. He told us about the "tunnel", and some unique maneuvering capabilities (and issues) it enabled, especially going astern. What a beautiful ship she is. Thank you, Ryan.
Thanks, Ryan. Am I the only one who wishes Drachinifel could be there for a REAL Drydock? That would be epic.
check the video "Live Drydock from a Drydock during Drydocking - Aboard USS New Jersey"
He was at the USS Texas while in Drydock and did at least 2 videos with the USS Texas Currator and you had to go to the their youtube video to see the rest.
These videos since the dry-docking of USS New Jersey are fascinating. We can all go to the museum ships and tour the sections inside or above the waterline, but these dry-dock vids are a once in a generation experience.
👍👍
The entire time that I was watching and listening to this video I could not help but to look at the shaping of the haul around the inboard props and think, "The size and tooling needed to shape that plate steel into that shape had to be huge!" and then there is the skill by the ship builders.
A really informative video , so well explained by Ryan . The engineering skills needed to keep those shafts turning through those sort of lengths without shaking the ship to bits are extremely high and it's not surprising they had problems finding the best combination of props . It's a problem with new ships even today despite all the computers used to design them .
I did think the propellers looked painted from earlier videos and it obviously makes sense for a museum ship . I wouldn't care to think of the strain on them and the shafts if they touched the bottom regularly . I must say for the last docking , thirty years ago has resulted in New Jersey looking in an excellent state of preservation below the waterline , they did a great job for all the visitors who come to see her .
I'm a "propellers are on airplanes, screws are on ships" guy.
Props on planes, screws on ships
Should spray the screws down again and collect some water off them. Then bottle it, seal it and auction it off labeled 'Battleship New Jersey "Prop Wash" 😅
That’s a BRILLIANT idea!
spinny doohickey thingies on the floaty thingy that does the movey thingy
Finally, technical terms that make sense! 😂
There was an argument about using 5-blade screws on the outboard, as those would have been smaller diameter, which meant less issues of "overhang" if alongside a pier or quay. However, as finally realized, the shaft positions meant that the 4 blade screw would be clear of the inboard hull dimension. In tests at the Towing Tank, the 4 blade screws helped give better turning response when put aback.
Massachusetts BB-59 started with 4 bladed props on all her shafts, and ended her career with 5 bladed outboard props and 3-bladed inboard props.
Let’s count how many people argue about “screws” versus “propellers.” Must be 500 by now. You must be so proud! Thanks Ryan for another fascinating video.
I say they’re “propellers” when you’re writing a report (especially an engineering report); but, they’re “screws” when you’re talking about them… especially with fellow sailors.
Jesus, honestly. As pointless arguments on the internet go, this one is admittedly pretty harmless, but that doesn't make it less pointless. I would argue the full technical term would be "screw propeller" (i.e. a device based on the principle of the Archimedes screw which is used to propel some kind of vessel, either vertically or horizontally), but even that's still just semantics. At the end of the day, words mean whatever the people who use them use them to mean (descriptivism > prescriptivism). And since people regularly use both terms without ambiguity, both terms are perfectly valid.
I haven't seen a lot of "arguing" here in the two weeks that have passed between your post and mine. Mostly everybody is just sharing stories and building camaraderie. That's a W, if you ask me.
----- It seems those slide ruler engineers knew what the heck they were doing when they built her.
Seen pictures of their office?
A high room full of guys working
The USS Coral Sea (CV-43) Also had 2 4 bladed screws and 2 5 bladed screws. This was done to make turn counting more difficult (she sounded like a friggin' washing machine).
Good point!
I'm sitting in Europe watching Battleship New Jersey video after video. Very interesting subjects you picked for presentation.
Different blade numbers also helps with resinence displaysment.
The way I’ve understood propellers is that every additional blade over two is less efficient. But the pulsing against the hull of a ship is more pronounced for a given thrust with fewer blades. (3 blades= high top speed while 4 blades = low speed power and smoother operation.)
I think that used to be the case earlier but as technology has advanced that's no longer so
Awesome shots tonight! Great job Ryan and Libby!!!
I feel like all my questions from the previous video have been answered 😂👍👍❤
Ooooo!!! Tactical Diameter discussion! HAWT. Would be cool to see the "Barn Door" emergency stop demonstrated while in dry dock, but I bet you can't because of the dry dock rules. Would still be cool to see!
I saw the picture and didn't look close, so I thought "OK, two five blade and two four blade, that's different", not noticing the counter pitch of the blades. Learning a lot from these episodes. Thank You.
Ryan, very interesting & informative video. Thanks! My father served in the US Navy in the Pacific Theater in WWII and he told me (before he passed away) that he always felt safer when one of the Iowa class battleships were in sight of his ship (USS Pasadena, CL65) due to their enormous firepower. So, I've had an interest in Iowa class ships (and most other Navy ships in WW2 era) since I was a boy.
very interested in details of the coatings you will be using for the hull and propellers. subscribed
You mentioned that the props were changed out to mitigate high speed induced vibration. It would be interesting to use modern computer generated fluid dynamics to study the harmonics of the equipment, proppellers and flow of seawater. Something similar was recently done to convert Union Pacific Big Boy locomotive 4014 to burn oil instead of coal. During WWII this was tried but found to be a failure no matter where the burners were placed in the firebox. After a study using computational fluid dynamics a solution was found and 4014 is happily plying the rails today. It would be interesting to see such a study on the Iowas' vibration problems. This type of study could be done on any ship where pertinent specs are available. Mr. Drachinifel is an engineer, perhaps he would know the proper people to conduct such a study. Cool video, thanks much!
We had a "fossil-fueled" electric generating power plant series in California that were designed to run on either oil or natural gas because of some market issues. These were designed and built in the 1950's and 1960's IIRC. There were different sets of burners and optimal locations for each that had to be swapped out to change fuels, and the heating profile within the boiler was also different with different tubes receiving more or less heat depending on the fueling. It made for a complex design, and that was just from a liquid to a gas fuel - coal would have made it even more different.
My father sailed on Wind-class icebreakers in the USCG, and he always called these "screws".
Holland tunnel, I love it
The reason for the dissimilar number blades has to do with sympathetic vibration. If all screws had the same number of blades their frequency would match and create a sympathetic vibration through the hull of ship. It was of the biggest concern on North Carolina's and Iowa's since the had screws outboard of the skegs. The vibration was not near as bad on South Dakota's as their screws where inboard of the skegs.
I think you mean resonance. Something that is often overlooked is that if the propellors had zero blades they'd be very inefficient.
@@TheJazsa80 my bad resonance is what creates the vibrations.
Painted props answered my question. Guessing they can’t slam an outboard prop in reverse for emergency turns? I kinda thought the dropping an anchor for a turn was movie BS.
Same reason that tracked vehicles have one more track-link on one side than the other
@@wdwerkerIt WAS movie bs.
I haven't seen a battleship screws but I have seen the screws on a Replenishment ship in rough seas from the fantail of an LPH. Pretty cool stuff. It's absolutely amazing how big ships are and everything on them.
I think it’s amazing to learn about the ship even out of the water. Some of the most interesting things are underwater where we don’t normally see it.
I went to Battleship Texas BB-35 when she was in dry dock it was amazing then.
I mean can you believe being on that big ship at 30 knots and then they would throw the helm hard over wow what a ride that must have been
One of the more fascinating clips on BB-62 I have seen
Ryan, I am from South Carolina so as you know we have the USS Yorktown and USS Laffey. I really hadn't thought about it but the New Jersey is a bigger ship than the Yorktown, I didn't think the battleships were as big as a Carrier. Now, I know the Modern Carriers are bigger than anything but those old Essex class is a smaller ship. New Jersey is a big ship, especially how old she is too.
We always referred to them as “screws” during my active duty service in the Navy 1967-69 on the USS Wiltsie DD-716 and the New Jersey.
Very smart hull shape. Stunning to see this magnificent ship out of the water.
While the ship is still out of the water, maybe a video could be done about the cutlass bearings.
Great work Ryan keeping our Battleship New Jersey alive
Ryan, I know you’ve visited the propeller shafts several times before. But it would be fascinating to see you go back as far as you could inside the skegs. Then, point out what spot that was on the outside now that she’s out of the water.
Well that's great news. You said in an earlier video you were thinking of keeping the screws. Now saying they will be repainted that means they are. Brilliant! It's like looking at a cow with only 3 legs it she hasn't got her screws on. That's really fantastic news. So pleased.
british Battleships had center divided bulkheads. which mean they had a tendency to roll over. or they just blow up. but that is just a sailors life
❤the channel. Awesome data.
Awesome, I am always fascinated with the propellers of ship's.
Man I really could use a big long format video about some of this drydock stuff. 8 minutes just barely wets my whistle
Ideally Ryan can get dedicated 4K resolution video of a full walk-around while she's in Drydock, and sell copies to generate more funding. Same for everything else once back at the museum site. I'd think serious modelers wouldn't have a problem getting a set of vids from all angles and with ideal lighting. Directly underneath, get some floodlights and take footage at night, gets things out of the shadows.
Mad props for another great vid 👍
Thanks for clearing that up Ryan, you do a great job of explaining everything, the Museum is very lucky to have you!👍
Screws! In german they are referred to as "Schrauben" which translates accordingly.❤😂
At the Washington State Ferry system (back when I was a deckhand anyway) we typically refered to the propeller as a propeller or a prop. I was familiar with the term wheel but I don't recall hearing it in conversational use.
Beautiful battleship, always wanted to take a look around one
Fun Fact: William Francis Francis Gibbs, a Maritime Visionary as I call him. Had a heavy influence on Warship and merchant ship design. To put this into perspective: Between 1940 through 1946, 63 percent of all merchant ships of 2,000 tons up and 74 percent of all American naval vessels (destroyers, landing craft, escort carriers, etc.) were built to the designs or working plans of Gibbs & Cox. ( The Company he Started with his Brother: Fredrick Gibbs ) Gibbs was the one who designed the liberty ships, the same ones that were built faster then they could be destroyed.
Gibb's master work however: The Ocean liner SS United States. was the Fastest Ocean Liner ever Built, was able to Reach a Blistering speeds ( Estimations from different perspectives and speed trials have a General area of between 38.6 Knots to 43 Knots) at a displacement of 45,400 tons, thanks in large part to the Engines and Boilers being I Think are the Same ones installed in the Iowa Class Battleships (4 × Westinghouse double-reduction geared steam turbines and 8 Babcock & Wilcox water-tube boilers) Gibbs Had Designed the United States too, like the Iowa's, come equipped with two, 5 bladed propellers, and two four bladed propellers Designed by a Gibbs & Cox female engineer Elaine Kaplan, in the same layout as the Iowa's. Gibbs also designed the ships with wartime and prior ship designing experiences in mind, he had Separated the main Engines into separate compartments like U.S Warships, as per the agreement with the U.S Government in-Exchange for carrying the bulk of the construction cost, They Wanted to make it possible for the ship to be used as a Troop Transport if the need arose.
Currently, the Ship has seen better Days, and is currently in a legal battle that could see it Evicted from its Pier due to a lack of funding.
I wish the Navy could give SSUS safe harbor, and free up the funds the Foundation is raising to be used for her upkeep rather than just mooring.
@@dougalexander5871 Yeah, Despite being an Ocean Liner, She is a fascinating Fusion of U.S Navy and Merchant Marine design, she may not have been as lavish as ships like queen Mary and Normandie. But she was built with Safety in mind to the point the only wood allowed on the ship was the butchers block, and a fire proof Mahogany Piano that had to be covered in gas and lit on fire! to see if the piano would burn after the gasoline was burned up. The Piano itself did not Catch fire.
I can look at those propellers for hrs!!😊
This is fascinating. I had no idea the elegant design of the propulsion system.
Amazing information.
I always understood that that the hull bottoms of Iowa class BB's and Midway Class CV's are nearly identical.
What is amazing is how old this technology is. And yet they still build new military ships, with the same setup. Now cruise ships use Azipods.
and are scrapped after 20 years too.
They also require a huge amount of electric power to operate them. Redundancy is also an issue with Azipods.
@@pwmoorejr that's not an issue with a nuclear powered vessel. What is a problem is their survivability on a warship.
Ships have had a lot of problems with azipods including some naval ships there are issues with their steering bearings, these can go bad in as little as 2 years! Azipods are favoured for Not needing big heavy shafts that have to be kept aligned. 😊
same setup on USS Midway CV 41
1 Screw Crew CV41 85-87.
@@stevencovington4715 70-80 m dIV. MATERIAL OFFICER
Great Information
Nicely done
You can export the program and post the file . I’ve shared my chirp plugs w others & it works . Great idea and video today . I’ve been following your repeater board you’ve been making .
Another interesting video…thanks
Great review.
Fascinating explanation. Thank you.
Fantastic backdrop bro!! Bravo!
Excellent narration. Thank you.
Thank you for this explanation
So Wise , Thank You .
So Fascinating thanks for answering my question !!!
This is one of the most interesting videos you’ve posted. Thanks so much 👏
Love this view and the explanation of why the props are different.
Really loving your series on the dry dock!
Great video! Thanks for answering my question from the comments section!!!
Looking at the back end of the Jersey as an engineer, I see the force vectors in my mind. Inboard propeller sucking water from both out side slipstream and the tunnel slipstream and shoving it past the huge airfoil shaped rudders. Crank those rudders over and we see maximum water deflection to one side creating a huge reaction force at right angles to its direction of travel. The sharp prow of the big ship against the water, 800 foot moment arm, provides the other reaction force spinning her in a tight circle. With the entire mass, long and lean, cranking at 32 knots, I am dead certain Admiral Spruance deliberately allowed the Nowaki to get away so she had to tell the rest of the Japanese Navy that we have full sized battleships capable of keeping up with destroyers and matching their turns! Psychological war at its finest.
'Airfoil'.
It's called a drop-shape.
No, these ships don't 'sail' either.
Funny enough, I saw the difference in the first picture in dry dock. I didn’t even bother asking why, I just knew there’d be a video to explain. Thanks Ryan for confirming of what I’d had 99.9% certainty; I just knew this would be explained.
I knew Ryan wouldn’t disappoint.
Great video, alot of information.
Great video thank you
Can't join in live tonight. Have to watch in replay later. I also believe that the United States had such an arrangement of props to reduce vibration. That is if I remember correctly.
Thank you for these videos. Good info from your expansion though some more time on the design drawings and layout would be appreciated . Enjoyed in Australia 🇦🇺
Thanks for a great explanation. I had no idea about the Holland tunnel or the configuration of the propellers and shafts.
Screw is what I would call the correct term, like a vessel with two is "Twin Screw", but I have never heard "Quad Screw" like an Iowa would be. Or even nona screw for those guys with 9 Mercs across their transoms. But we also use "wheel" as a convenient slang term (somehow sounds less pompous). Even though it's proper we avoid saying "prop" or "propeller" simply because it's a mouthful.
To me the reason for an odd number of blades trailing a skeg is because a four (or 2) blade will have half its blades simultaneously banging into "hard" (oops too technical?) water as they spin out of the "soft" water trailing the skeg. I think this will vibrate more than if 1 out of 5 (or 1 out of 3) is in the soft water at any given time.
Someone said that the two forward propellers are in "clean" water, while the outboard halves of the aft props are operating in water which has been accelerated by the two forward props. To this I would add that all four are trying to push her ahead in water which is actually travelling the same way as it's dragged along with the ship. Some say as much as 20% as your speed.
Blade tip speed Does matter; that's where cavitation is going to be worst, and it's very destructive. Supposedly around 12,000 ft/minute is max for the blade to get a grip on the water.
Another problem is blade tip clearance from the hull. The approaching blade is going to bang some water against the hull and we always try to leave at least 10% of the prop diameter clearance. Otherwise the vibration will drive you nuts. But I'm not seeing that here on the New Jersey. One guy with a 40' boat went for max diameter which barely cleared the bottom of the boat and that was not only noisy, it induced a lot of vibration.
Lastly, think about how propellers actually "pump" water sideways. The forward starboard wheel, which is "right handed" because it spins clockwise when in "forward", when viewed from behind, is actually taking water from the right side of the boat and throwing it to the left. I'm calling them "wheels" now because that's the effect they have: like a wheel they're rolling the stern from left to right by throwing that water sideways. If only the starboard wheel was turning, it's not hard to imagine that would make her turn sharper. Or if the port wheel was in reverse, sharper still. Whether she was moving forward or not, they would still be pumping water sideways and wanting to turn left.
When you have a small boat, with only a single screw right hand wheel, this will cause the common situation where "She backs to port" when that prop is spinning in reverse. Stealing the water from your port quarter and depositing it on the starboard side, which is especially noticeable before she gathers sternway but actually is going on the whole time.
New Jersey's two aft propellers, being closer to center, don't have as much leverage to turn her but make up for that by shoving water into the rudders which deflect that water towards one side or the other, whether she has way on or not.
How's that for a whole lot of nothing?
Thanks
All the devices that convert some type of rotary motion to linear motion are "propellers". Side wheel and stern wheel propellers were some of the first types used, Rotary propellers (shortened to rotors) for helicopter's, and "screw propellers" for shafts that are inline with the direction of travel in airplanes and ships. The word "prop" is just convenient slang. It is like a dove is a pigeon, but a pigeon may not be a dove.
uh, no, that is incorrect. You also have IMPELLERS as well. Think of wetbikes. Those rotac engines are even supercharged now making 200+ horsepower, and they use IMPELLERS.
Drawing vs. pushing is the best way to think of the difference, without getting super technical into blade layout and design and all that. You don't need to comprehend the law of flow around an orifice and other advanced engineering concepts to grok this stuff. :D
Very interesting indeed 👍
Thank you for your dedication. I spent my life in engineering and in Naval ships when young, The installation of propeller close to the hull is an " unsymmetrical installation and so pressure impulses due to the low number of blades will cause vibrations, A shrouded propeller will reintroduce some symmetry of the flow into the propeller, The ships hog and sag and twist and flex more than people think.
Engineers need to wrap and make naked people wear around them all sorts of prosthetic aids as when naked and bare all people on earth cannot do much,
Now we all life having to wear and wrap around us an engineered prosthetic aid like any child born without legs or any one suffering an amputation after a military mission, All Miltary personnel are all looked after by engineers adapting prosthetic aids to be worn on land sea and air.
Our psychology makes us view these miltary prosthetic aids as being very beautiful in protecting naked people, starting with a pair of shoes and socks.
I really enjoyed this one for the very complex design considerations.
Screws. The only valid answer 😉☺️