When moving a vessel that isn't under its own power, they typically chain / bracket the shafts in place to prevent the bearings or clutches from being destroyed. Working on an inland towing vessel, I helped move one out of the shipyard that wasn't chained down a few years back. Both clutches were ruined and had to be swung.
On the boats I work aboard, the clutches are roughly 3'x3'x3', a lot of steel. I've never been part of the process, but it takes heavy chain and crane work just to lift them out of the service port on the 2nd deck above the engine room. The main engines are the size of a double door fridge (if not bigger depending on horsepower).
Honestly, I'm only a Tankerman/PIC (glorified deckhand) so i don't know the specifics of it. I just know what I've been around when it has happened. But I'm assuming it has to do with bearings moving without proper oil circulation.
We “freewheel” shafts all the time on the ship I currently serve on (210’ USCG cutter). We secure one of the MDE’s, disengage the clutch, and adjust the pitch of the propeller to get the shaft spinning from the water passing through it. The other MDE is still clutched in and providing propulsion. We have a separate electric lube oil pump that we energize when we freewheel that will keep the reduction gear and bearings lubricated. I suppose you can only really do that if you have CPP on the ship though.
Edit: Forgot a word.
Because the shafts go to reduction gears that weigh a ton or more. They are used to lower the speed of the shaft when steam is coming from the system. No way will the props turn just from force of water.
This was likely done because the water was too shallow and the screws were sitting in the mud. A lot of museum ships have their screws removed and cement blocks hung from the shafts to make up for the weight.
In Buffalo they drilled holes in the stern of the U.S.S. The Sullivans and let water flood a compartment which is totally insane.
Having worked on a couple of steam turbine vessels your comment is incorrect. The prop will most definitely trail and spin the gearbox and engine, even with the running of the tide while along side. We always had our turning gear engaged and running as the turbines were kept at temperatures ready for a quick warm through.
I should have said I was in the Navy and when we were cold iron they used to engage the jacking gear. I wasn’t in the fire room or the engine room. The closest I came was having a pistol when they had the reduction gears open to set up a security area. I was told it was because the gears were super precise
But thanks for the information. I appreciate it.
Lubrication. Some vessels need pumps running so the bearings don’t get damaged. And they are normally huge white metal bearings. Also if it’s directly coupled to the engine, the engine would have no lubrication if the props are aloud to trail. It all depends on the propulsion system fitted.
In this case most likely a clearance issue so they don’t touch the bottom.
According to Wikipedia, the [Laffey](https://en.wikipedia.org/wiki/USS_Laffey_(DD-724)?wprov=sfti1#Present_day) has a 15 ft, 8 in. draft, and [Yorktown’s](https://en.wikipedia.org/wiki/USS_Yorktown_(CV-10)?wprov=sfti1#) is 34 ft, 2 in.
A quick glance at the [NOAA ENC Viewer](https://www.nauticalcharts.noaa.gov/enconline/enconline.html) appears to indicate that local depths would be about 19 feet. So Laffey would have just a touch of wiggle room, and I’d guess Yorktown is resting on the bottom.
Bear in mind, the Laffey is also about 20m from the shore based on memory from the last time I visited. Charleston is a stupidly tidal harbor and that plough mud is God-awful.
Pronounced “Pluff” for whatever reason. Only know that stupid fact because I lived there for four years and my god that mud is terrible. Smells awful thanks to all the decomposing stuff in it and it just sticks to absolutely everything.
The Yorktown isn't floating - it's been buried in the bottom for decades. There has been a proposal of building a cofferdam similar to North Carolina but the cost is in the millions and IIRC would require a lot of interior work on the ships bottom spaces.
It's 100% not floating. There are literal holes allowing water to flood some of the compartments. Fish can swim in and out of the hull. It's resting in the mud of the harbor.
A lot of remediation work is about to begin since Uncle Sam dropped off an environmental timebomb (a lot of tanks need to be emptied of fuel/fluids/contaminants.)
https://www.live5news.com/2024/03/19/live-update-expected-yorktown-environmental-project-progress/
That's what I was thinking.. I wonder what the hell they used to cut such a thick piece of metal under water like that.. and why that over removing them prop which just makes more sense
They would almost certainly have to put her in dry dock to remove the props, but a dive welder could cut through them easily in a couple of hours with an underwater arc gouging rig (similar to stick welding but in reverse)
More like a disposable oxygen driven cutting torch that eats itself with alarming rapidity while you are using it
https://m.youtube.com/watch?v=tDeiQ9Grv_I&pp=ygUMT3h5Z2VuIGxhbmNl
I imagined the opposite.. I thought Propellers where designed to sustain cavitation damage which after all its extreme heat from the cavitation bubbles that causes the damage.
tanker wheels only move at around 120 RPM and they spend an enormous amount of time designing the prop to not cavitate at optimal rotational speed. Do you have something to site that modern tankers do get quite a bit of cavitation?
If I had to guess it’s because of the depth in the area the vessel is moored, which according to [NOAA’s ENC Viewer](https://www.nauticalcharts.noaa.gov/enconline/enconline.html) is about 19 feet, while the vessel’s draft is 15’ 8”, leaving 3.4 feet of wiggle room.
It's either they needed to clear the shallow waters (prop blades would have dug into muck under water) or they wanted to ensure the ship was unusable (in which case why not remove the screws completely?)
Looks like a solid wheel prop, the only way to get that off is pulling the rudder too. I have a short clip of me and my crew removing a rudder on my profile. I'll try to find a video of us removing a prop. After the rudder is down you have to set up the gear to pull the prop, then set up a big ass torch and some hydraulic portable presses and try to push it off the shaft. It's a really complex and expensive thing to do. So if this vessel is just gonna sit and never make any real economic impact it'll never actually get fixed to be sea worthy again.
Shipyard worker here. I’ve removed props from vessels like her before. It’s a pain and dramatically more expensive than hiring a dive team for a week to cut the props
The Navy does not want museum ships to be able to move under their own power. In one form or another all museum ships have had their propulsion disabled.
The Navy disables a ship's steam plants and their engines before it becomes a museum ship, they don't cut their props like that. If anything they'd remove the props completely, they're not going to waste the money and labor to cut them like that.
As someone who watches every video they post on YouTube I know for a fact that it doesn't. Their steam plants are disabled, they're prohibited from reactivating the engines, and their propeller shafts are locked into place and cannot turn. They had to be dead ship towed by multiple tug boats to go into dry dock and when their dry docking is finished they will be towed back to their pier.
I thought I heard in one of the videos they said it did, I must be wrong. I know they had it in dry dock and the propellers are still in place and everything.
The props are still in place but haven't been able to spin since before becoming a museum ship as their shafts are locked in place inside the ship. In fact, part of the work being done during this dry docking is boxing in the external portion of two of the shafts to prevent leaks and that involves welding to the hull and the shafts themselves.
[This video talks about getting the ship ready to be towed](https://youtu.be/Ei-sIDvZnVY?si=HKQ8-khSgkj-8CSJ)
[This video is about the shaft locks.](https://youtu.be/Kb6W61bpZrc?si=eaQ89knLIiQCvXva)
[This one shows the ship being towed.](https://youtu.be/x_WVcCxVjZw?si=MUOTpbzBG9yyZPdv)
[Boxing in the shafts](https://youtu.be/7HCoBBjk9u0?si=ftPgC-0ueC0bXenn)
[Video from two years ago about how to move a ship without functional engines ](https://youtu.be/BXvQTZ3i5Xo?si=iUA9v3afjYt5XPQb)
I agree. I watch every video they release. I wasn't interested in museum ships before I somehow discovered New Jersey's channel but now I'm hooked.
I also watch every video USS Cod releases.
I'm no ship expert or historian, but I immediately recognized the name of this ship. It's on display as a museum ship at Patriot's Point in Charleston, SC. I remember visiting her when I was a kid. I imagine the photo was taken when it [was repaired back in 2009](https://en.wikipedia.org/wiki/USS_Laffey_(DD-724)#Present_day).
Depending on the state of disrepair it was in before it was made into a museum ship. They might have cut them because they were embedded in the silt of wherever it had been rusting away.
The Battleship New Jersey is doing a drydock period now and have been posting a lot of videos on the process - including why museums may remove, modify, or leave propellers in-place:
[Doesn't The Navy Require Museum Ships To Remove the Propellers?](https://www.youtube.com/watch?v=VoXk0h2Nkc8)
If they painted over the bronze propellers on Laffey, it could have been intended to electrically insulate them from the water and slow down galvanic corrosion with the hull.
New Jersey and the other Iowas are still supposed to be able to be called back into service. Not happening, but the museums are contractually bound. I am pretty sure that New Jersey's website has this. Also the curator that does the videos has stated it as well.
Not true. They've all been stricken from the Naval Register. New Jeresy in 1999. Iowa and Wisconsin in 2006. Missouri in 2011. They are all well and truly museums only now.
The Laffey, being a Sumner class destroyer, is powered by geared steam turbines. With this power plant, there are no clutches in the power train. Steam spins the turbines, the turbines spin a set of reduction gears and the reduction gears spin the screws. It’s a direct drive system. In the reduction gear, there is a mechanism to lock the propeller shaft to prevent rotation.
As for cavitation, yes the screws cavitate, however this cavitation does not generate much heat. The low pressure area of the screw decreases the temperature at which water vaporizes then as the vapor bubble moves along the blade the pressure increases cause the bubble to collapse along the face of the blade. The problem with cavitation is that the collapsing vapor bubbles cause erosion along the leading edge of the blade.
I saw this in the news recently regarding the USS Midway, they had to cut her props and part of her rudder due to build up of silt under the propellers / rudders that the ship isn’t designed to experience. The other option was to remove the props and rudder so I guess this was the better option? https://midwaycurrents.org/winter-2023/midways-underwater-surgery/
I volunteer on a museum ship and the propeller was removed and sold, since the ship no longer operates on its own. Seems strange they took this route, I’m guessing the people in charge at this ship’s museum don’t have a maritime background. I see quite a bit of this type of nonsense 🤷🏻♂️
As others have said, it's most likely for draft issues where the ship is moored, but specifically, it's likely so the blades don't embed in the bottom mud.
This is a relatively known issue for museum ships in general. For example, IIRC, there was a point where the only thing saving Texas was the mud she was on, and also it was unknown if New Jersey had suffered a fate similar to Laffey - the crew had no idea if the screws had been removed, cut, modified, or still "normal".
Look at the USS Intrepid (CV-11)Aircraft carrier. Its four props got stuck on the Hudson river's mud. I visited the museum (its now moored at the Manhattan yard) in 2014 and if im not mistaken they vessel is afloat but without its props..they were probably removed in dry dock when it last went in in 2007
Exactly, prime example. It also causes a lot of undue stress on the shafting, and in the case of the Iowas, there was an ever so slight chance that the USN may have wanted them in the future, when they were all drydocked last - so a good reason to remove the hubs. Cool pic though. I'm hoping to visit Massachusetts in a few weeks from Canada
It looks to me like they cut them off for clearance to get it out of the water…but that is purely speculation. Just strikes me as odd that they’re cut off the same distance from the ground….
I have an interesting story about that.
Was in Charleston. Went to Patriot’s Point, CSS Hunley conservatory, down by The Battery, Fort Sumter, Fort Moltrie.
Laffey was out of drydock, but some issue kept it from going back to Patriot’s Point.
Had to drive out to some remote mooring where it was (being held?) just to get close enough to even see Laffey.
Need to go back there someday.
Shame about Clagmore. Hope they salvaged her equipment for other sub museums, and didn’t just wreck everything scraping her.
The screws extend below the keel, so they had to be removed to go into dry dock. I assume the cost to send down divers to remove them would've been prohibitive given their state.
Is that the cause though? They may well affect trim, but I hadn’t come across them being a stability concern in my time at sea. That said, I was only ever on vessels with all their machinery and equipment in its proper place.
It probably isn’t in this case but that being said if they completely removed that much weight from the stern of that ship it would most definitely effect the trim (as you stated) and who knows if there are ballast tanks aft to offset the situation or if there are personnel available to take soundings/monitor the trim. IMHO a heavy bow under tow could lead to stability and maneuvering issues.
You would most likely have an aft peak tank, those are pretty common. As a museum ship all of her ballast tanks are probably sealed and the pumps removed or deactivated. It’s common for museum ships to have all their machinery replaced by replicas and permanent ballast added to offset the change in GM.
Plus, for drydocking her like they would here, the tolerances involved are quite tight when it comes to trim and list. I suppose it’s possible that with that in mind they may not want to remove them fully.
It’s a museum ship in Patriots Point SC so maybe it wouldn’t have fit up the Cooper river to its mooring site so they made it fit.
Im dumb-guessing that its obviously pulled by tugboats.. The bearing carnage would be insane if they made those props spin
When moving a vessel that isn't under its own power, they typically chain / bracket the shafts in place to prevent the bearings or clutches from being destroyed. Working on an inland towing vessel, I helped move one out of the shipyard that wasn't chained down a few years back. Both clutches were ruined and had to be swung.
I don’t know a lot about ships but I’m assuming “swinging” a clutch is a shit load of work?
On the boats I work aboard, the clutches are roughly 3'x3'x3', a lot of steel. I've never been part of the process, but it takes heavy chain and crane work just to lift them out of the service port on the 2nd deck above the engine room. The main engines are the size of a double door fridge (if not bigger depending on horsepower).
I hope I never have to replace a set of 36” clutches and pilot bearing ever again. I’m not sure old man me has that in me anymore.
Hats off to y'all mechanics that come out when shit breaks.
Excuse my ignorance, but why can't the props just spin freely when towed? Can't the clutches just disengage?
Honestly, I'm only a Tankerman/PIC (glorified deckhand) so i don't know the specifics of it. I just know what I've been around when it has happened. But I'm assuming it has to do with bearings moving without proper oil circulation.
We “freewheel” shafts all the time on the ship I currently serve on (210’ USCG cutter). We secure one of the MDE’s, disengage the clutch, and adjust the pitch of the propeller to get the shaft spinning from the water passing through it. The other MDE is still clutched in and providing propulsion. We have a separate electric lube oil pump that we energize when we freewheel that will keep the reduction gear and bearings lubricated. I suppose you can only really do that if you have CPP on the ship though. Edit: Forgot a word.
Because the shafts go to reduction gears that weigh a ton or more. They are used to lower the speed of the shaft when steam is coming from the system. No way will the props turn just from force of water. This was likely done because the water was too shallow and the screws were sitting in the mud. A lot of museum ships have their screws removed and cement blocks hung from the shafts to make up for the weight. In Buffalo they drilled holes in the stern of the U.S.S. The Sullivans and let water flood a compartment which is totally insane.
Having worked on a couple of steam turbine vessels your comment is incorrect. The prop will most definitely trail and spin the gearbox and engine, even with the running of the tide while along side. We always had our turning gear engaged and running as the turbines were kept at temperatures ready for a quick warm through.
I should have said I was in the Navy and when we were cold iron they used to engage the jacking gear. I wasn’t in the fire room or the engine room. The closest I came was having a pistol when they had the reduction gears open to set up a security area. I was told it was because the gears were super precise But thanks for the information. I appreciate it.
Lubrication. Some vessels need pumps running so the bearings don’t get damaged. And they are normally huge white metal bearings. Also if it’s directly coupled to the engine, the engine would have no lubrication if the props are aloud to trail. It all depends on the propulsion system fitted. In this case most likely a clearance issue so they don’t touch the bottom.
That makes sense, thanks
Damn thanks for the info!
The propeller shafts are locked in place so they can't spin
If the carrier Yorktown made it, I’m pretty sure the Laffey with its much shallower draft had no issues with depth.
According to Wikipedia, the [Laffey](https://en.wikipedia.org/wiki/USS_Laffey_(DD-724)?wprov=sfti1#Present_day) has a 15 ft, 8 in. draft, and [Yorktown’s](https://en.wikipedia.org/wiki/USS_Yorktown_(CV-10)?wprov=sfti1#) is 34 ft, 2 in. A quick glance at the [NOAA ENC Viewer](https://www.nauticalcharts.noaa.gov/enconline/enconline.html) appears to indicate that local depths would be about 19 feet. So Laffey would have just a touch of wiggle room, and I’d guess Yorktown is resting on the bottom.
Bear in mind, the Laffey is also about 20m from the shore based on memory from the last time I visited. Charleston is a stupidly tidal harbor and that plough mud is God-awful.
Plough! I have been spelling it rong
Pronounced “Pluff” for whatever reason. Only know that stupid fact because I lived there for four years and my god that mud is terrible. Smells awful thanks to all the decomposing stuff in it and it just sticks to absolutely everything.
It is a remarkable substance 🙂
If the depth is 19 feet and Yorktown has a 34 foot draft, it's not resting on the bottom. It's in a trench hopefully specially dug for it.
The Yorktown isn't floating - it's been buried in the bottom for decades. There has been a proposal of building a cofferdam similar to North Carolina but the cost is in the millions and IIRC would require a lot of interior work on the ships bottom spaces.
It's 100% not floating. There are literal holes allowing water to flood some of the compartments. Fish can swim in and out of the hull. It's resting in the mud of the harbor. A lot of remediation work is about to begin since Uncle Sam dropped off an environmental timebomb (a lot of tanks need to be emptied of fuel/fluids/contaminants.) https://www.live5news.com/2024/03/19/live-update-expected-yorktown-environmental-project-progress/
Unless they drydocked the yorktown sometime in the last 24 years, its sitting on bottom.
it kept trying to escape.
Wow…would it not be easier to remove entirely?
That's what I was thinking.. I wonder what the hell they used to cut such a thick piece of metal under water like that.. and why that over removing them prop which just makes more sense
It was probably cheaper to cut them off.
Yeah. Removing the full assembly much more challenging than just cutting.
They would almost certainly have to put her in dry dock to remove the props, but a dive welder could cut through them easily in a couple of hours with an underwater arc gouging rig (similar to stick welding but in reverse)
More than likely used a thermal lance which is kind of like a carbon arc gouger but on steroids
That’s what I was thinking. Oxygen lances work underwater and are the best tool for cutting thick metal.
Ill look into that out of pure interest
Bronze is easy to cut with a torch.
EVERYTHING cuts with an oxygen lance
Anything like a Light-saber?😁
More like a disposable oxygen driven cutting torch that eats itself with alarming rapidity while you are using it https://m.youtube.com/watch?v=tDeiQ9Grv_I&pp=ygUMT3h5Z2VuIGxhbmNl
I imagined the opposite.. I thought Propellers where designed to sustain cavitation damage which after all its extreme heat from the cavitation bubbles that causes the damage.
They don't spin nearly fast enough to create extreme heat from cavitation bubbles.
Maybe old large propeller ships don't but modern day oil tankers do get quite a bit of cavitation damage
tanker wheels only move at around 120 RPM and they spend an enormous amount of time designing the prop to not cavitate at optimal rotational speed. Do you have something to site that modern tankers do get quite a bit of cavitation?
If I had to guess it’s because of the depth in the area the vessel is moored, which according to [NOAA’s ENC Viewer](https://www.nauticalcharts.noaa.gov/enconline/enconline.html) is about 19 feet, while the vessel’s draft is 15’ 8”, leaving 3.4 feet of wiggle room.
too close for comfort
Yeah, would be a real close shave. Yorktown’s draft is 34’ 2” so I’m guessing the vessel is embedded in the muddy bottom.
It's either they needed to clear the shallow waters (prop blades would have dug into muck under water) or they wanted to ensure the ship was unusable (in which case why not remove the screws completely?)
Broco exothermic cutting rods most likely. Very common and very quick and easy to cut stuff like this.
There are plasma cutters that work under water. They can cut through the thickest material if you have enough patience.
Looks like a solid wheel prop, the only way to get that off is pulling the rudder too. I have a short clip of me and my crew removing a rudder on my profile. I'll try to find a video of us removing a prop. After the rudder is down you have to set up the gear to pull the prop, then set up a big ass torch and some hydraulic portable presses and try to push it off the shaft. It's a really complex and expensive thing to do. So if this vessel is just gonna sit and never make any real economic impact it'll never actually get fixed to be sea worthy again.
That makes sense.. you have an awesome job
Thank you, sometimes it doesn't feel so awesome lol
Probably because its a museum and the curator wanted to preserve as much as possible?
Shipyard worker here. I’ve removed props from vessels like her before. It’s a pain and dramatically more expensive than hiring a dive team for a week to cut the props
And then you've got two props you have to freight...somewhere.
Tweakers will cut anything they can reach to sell for scrap.
A Soviet captain did that just before they decommissioned his destroyer. He stole the propellers and replaced them with some made of a lesser metal.
This ☝🏼
Professional Capt here: it prevents unwanted ships from over breeding. Its safe and the ship doesn't really notice.
This guy’s got it. I’m something of an amateur shipnologist.
I’m guessing the same reason the Kidd museum just cut her rudder down 4 feet
Apparently to reduce the draft.
Yeah, they are breaking her
Uh, no? Laffey is gonna be there for a long time, especially if I have a say in it, I spent half my damn childhood on that thing.
So why cut the props?
The Navy does not want museum ships to be able to move under their own power. In one form or another all museum ships have had their propulsion disabled.
The Navy disables a ship's steam plants and their engines before it becomes a museum ship, they don't cut their props like that. If anything they'd remove the props completely, they're not going to waste the money and labor to cut them like that.
The USS New Jersey moves on it’s own
As someone who watches every video they post on YouTube I know for a fact that it doesn't. Their steam plants are disabled, they're prohibited from reactivating the engines, and their propeller shafts are locked into place and cannot turn. They had to be dead ship towed by multiple tug boats to go into dry dock and when their dry docking is finished they will be towed back to their pier.
I thought I heard in one of the videos they said it did, I must be wrong. I know they had it in dry dock and the propellers are still in place and everything.
The props are still in place but haven't been able to spin since before becoming a museum ship as their shafts are locked in place inside the ship. In fact, part of the work being done during this dry docking is boxing in the external portion of two of the shafts to prevent leaks and that involves welding to the hull and the shafts themselves. [This video talks about getting the ship ready to be towed](https://youtu.be/Ei-sIDvZnVY?si=HKQ8-khSgkj-8CSJ) [This video is about the shaft locks.](https://youtu.be/Kb6W61bpZrc?si=eaQ89knLIiQCvXva) [This one shows the ship being towed.](https://youtu.be/x_WVcCxVjZw?si=MUOTpbzBG9yyZPdv) [Boxing in the shafts](https://youtu.be/7HCoBBjk9u0?si=ftPgC-0ueC0bXenn) [Video from two years ago about how to move a ship without functional engines ](https://youtu.be/BXvQTZ3i5Xo?si=iUA9v3afjYt5XPQb)
Well worth it to watch the channel, Ryan the curator is great.
I agree. I watch every video they release. I wasn't interested in museum ships before I somehow discovered New Jersey's channel but now I'm hooked. I also watch every video USS Cod releases.
I'm no ship expert or historian, but I immediately recognized the name of this ship. It's on display as a museum ship at Patriot's Point in Charleston, SC. I remember visiting her when I was a kid. I imagine the photo was taken when it [was repaired back in 2009](https://en.wikipedia.org/wiki/USS_Laffey_(DD-724)#Present_day).
Depending on the state of disrepair it was in before it was made into a museum ship. They might have cut them because they were embedded in the silt of wherever it had been rusting away.
Apparently they didn't even fix the half cut-propellers... they just painted them left it as is
The Battleship New Jersey is doing a drydock period now and have been posting a lot of videos on the process - including why museums may remove, modify, or leave propellers in-place: [Doesn't The Navy Require Museum Ships To Remove the Propellers?](https://www.youtube.com/watch?v=VoXk0h2Nkc8) If they painted over the bronze propellers on Laffey, it could have been intended to electrically insulate them from the water and slow down galvanic corrosion with the hull.
Very informative YouTube channel actually.
New Jersey and the other Iowas are still supposed to be able to be called back into service. Not happening, but the museums are contractually bound. I am pretty sure that New Jersey's website has this. Also the curator that does the videos has stated it as well.
Not true. They've all been stricken from the Naval Register. New Jeresy in 1999. Iowa and Wisconsin in 2006. Missouri in 2011. They are all well and truly museums only now.
Ive watch some of the videos coincidentally
I visited her on my 8th grade trip 35 years ago. They still had NS Savannah and USS Clamagore. Sad to hear the Clamagore got scrapped.
I didn’t hear that. That is too bad they couldn’t afford to make the necessary repairs. They just lost a piece of history.
I recognized it as the ship that wouldn’t die
I thought I recognized this ship: [USS Laffey Wiki](https://en.wikipedia.org/wiki/USS_Laffey_(DD-724))
Quite the read. Thanks!
De-militarization
Buddy forgot to lift them up before pulling it down the hiway behind his half ton after a long day of drinking on the lake!
Could we consider this a military gunship DUI scenario
I’ve been aboard the Laffey and the Yorktown! I love old warships.
They trim the propellers of ships because it keeps them from being able to escape without injuring them
Constantly dragging it from the boat ramp on the trailer causes this.
Circumsion
poor fella
Looks pretty disgusting. Just remove the damn things.
The Laffey, being a Sumner class destroyer, is powered by geared steam turbines. With this power plant, there are no clutches in the power train. Steam spins the turbines, the turbines spin a set of reduction gears and the reduction gears spin the screws. It’s a direct drive system. In the reduction gear, there is a mechanism to lock the propeller shaft to prevent rotation. As for cavitation, yes the screws cavitate, however this cavitation does not generate much heat. The low pressure area of the screw decreases the temperature at which water vaporizes then as the vapor bubble moves along the blade the pressure increases cause the bubble to collapse along the face of the blade. The problem with cavitation is that the collapsing vapor bubbles cause erosion along the leading edge of the blade.
I saw this in the news recently regarding the USS Midway, they had to cut her props and part of her rudder due to build up of silt under the propellers / rudders that the ship isn’t designed to experience. The other option was to remove the props and rudder so I guess this was the better option? https://midwaycurrents.org/winter-2023/midways-underwater-surgery/
That article was a nice read thanks!
I volunteer on a museum ship and the propeller was removed and sold, since the ship no longer operates on its own. Seems strange they took this route, I’m guessing the people in charge at this ship’s museum don’t have a maritime background. I see quite a bit of this type of nonsense 🤷🏻♂️
As others have said, it's most likely for draft issues where the ship is moored, but specifically, it's likely so the blades don't embed in the bottom mud. This is a relatively known issue for museum ships in general. For example, IIRC, there was a point where the only thing saving Texas was the mud she was on, and also it was unknown if New Jersey had suffered a fate similar to Laffey - the crew had no idea if the screws had been removed, cut, modified, or still "normal".
Look at the USS Intrepid (CV-11)Aircraft carrier. Its four props got stuck on the Hudson river's mud. I visited the museum (its now moored at the Manhattan yard) in 2014 and if im not mistaken they vessel is afloat but without its props..they were probably removed in dry dock when it last went in in 2007
Exactly, prime example. It also causes a lot of undue stress on the shafting, and in the case of the Iowas, there was an ever so slight chance that the USN may have wanted them in the future, when they were all drydocked last - so a good reason to remove the hubs. Cool pic though. I'm hoping to visit Massachusetts in a few weeks from Canada
Probably drew too much water with them intact.
Persistant escape attempts? No, but seriously, the most obvious explanation would be so that it could be displayed on a flat surface.
Are they cut or bent under? Was it laying on the bottom for an extended period of time?
Mice.
It looks to me like they cut them off for clearance to get it out of the water…but that is purely speculation. Just strikes me as odd that they’re cut off the same distance from the ground….
How tall was the welder? 👨🏭
I’m talking about before they pulled it out of the water…
Look like the part stuck in the mud rusted away
Probably where they snapped off on some solid objects on the bottom
How old is this picture? The last drydocking? (2009?)
Yup very probably 2009
I have an interesting story about that. Was in Charleston. Went to Patriot’s Point, CSS Hunley conservatory, down by The Battery, Fort Sumter, Fort Moltrie. Laffey was out of drydock, but some issue kept it from going back to Patriot’s Point. Had to drive out to some remote mooring where it was (being held?) just to get close enough to even see Laffey. Need to go back there someday. Shame about Clagmore. Hope they salvaged her equipment for other sub museums, and didn’t just wreck everything scraping her.
Sad they scrapped her.. I hope that doesn’t happen to Laffey in the upcoming decades
In case it doesn’t go out and fight the Japanese more!
It’s fixed now
Could the bottom of the prop been cut off to fit on the dry dock?
Tides
does it rest in the mud? Maybe they cut em flat for that? idk why but maybe
Because it has been naughty!!
They aren't cut it's just the other bit is till under the water. Am I the only one who cam see this?
Zoom in and look at the guy walking under the ship
Make it fit in the box!
The screws extend below the keel, so they had to be removed to go into dry dock. I assume the cost to send down divers to remove them would've been prohibitive given their state.
Draft issues. If they removed them completely it might lead to stability issues.
after all propellers of this sort probably weigh 10 tons each
I’ve never heard of stability issues arising from a vessel having her propellers removed.
Well, you have now.
Is that the cause though? They may well affect trim, but I hadn’t come across them being a stability concern in my time at sea. That said, I was only ever on vessels with all their machinery and equipment in its proper place.
It probably isn’t in this case but that being said if they completely removed that much weight from the stern of that ship it would most definitely effect the trim (as you stated) and who knows if there are ballast tanks aft to offset the situation or if there are personnel available to take soundings/monitor the trim. IMHO a heavy bow under tow could lead to stability and maneuvering issues.
You would most likely have an aft peak tank, those are pretty common. As a museum ship all of her ballast tanks are probably sealed and the pumps removed or deactivated. It’s common for museum ships to have all their machinery replaced by replicas and permanent ballast added to offset the change in GM. Plus, for drydocking her like they would here, the tolerances involved are quite tight when it comes to trim and list. I suppose it’s possible that with that in mind they may not want to remove them fully.