Yes, and that often works, but it doesn’t always. A vessel that loses propulsion in good weather, and/or with lots of sea room and/or above good holding ground (where anchors can get and maintain a good hold) will usually be OK. However, if they lose propulsion where there is little room to manouevre they will often be aground before anything can be done. Or they’ll get an anchor down but won’t be able to prevent the vessel swinging on its anchor into shallows. Or in losing propulsion they will be in a bit of a panic and foul the anchors when letting go. Or if there is a major engine room problem they may lose power to the anchor winches. Or in very bad weather the anchors just won’t be able to hold the vessel and they will drag. Very often it’s a combination of things.
Were there a lot of other WWII ships like the Porstmouth that got decommissioned so rapidly (~5 years after launch) due to wartime manufacturing overkill?
Its cool they found another use for her, but how many ships just got mothballed and rusted away?
I’ve driven past the Philadelphia Naval yard before (around 1991) and there were a LOT of ships…just sitting there. Is there a constant scrapping program going on to at least recycle the steel and reusable parts? How long do ships just sit there?
Yes, they can run backward. The engine is stopped, different cam arraignments are made (or the modern equivalent if the valves are not cam driven) and they are restarted backward. And there are few electric motors that would crank such an engine. Starting is done by valving compressed air to the appropriate cylinder. One of the reasons for the donkey engines is so that air can be compressed to start the main engine, should all the air be used up on failed starting attempts.
A tangent about stopping and reversing ships…
This is how a large steam-powered military vessel stops or reverses:
In a typical set of main engines, there is a High Pressure Turbine and a Low Pressure Turbine, both connected to a set of reduction gears.
The throttle steam goes into the narrow end of the HP turbine, expands while turning the blades, goes through a moisture separator, and then goes into the center of the hourglass-shaped LP turbine, turns those blades, and then goes to the condenser.
The shafts both go through a double reduction gear set. These are huge. The bull gear is often 12 feet in diameter. The teeth are much finer than the illustration shows; you can see this in the photo above (the gears and housing fill the bottom half of the photo).
There is no concept of a clutch or changeable gears: to reverse the main shaft, you must reverse the engines.
This is done by admitting steam to two small turbines attached to the end of the LP turbine. They are marked in the photo, but you can see them much better in this cutaway diagram.
To reverse the shaft, the throttleman first shuts the forward throttles, then wings open the astern throttles, admitting steam to the astern elements.
The astern turbines are highly inefficient, generating maybe 10% of the maximum HP available in the forward direction. However, since the ship doesn’t really go backwards often and when they do they don’t care how much energy they waste, this arrangement works.
The single propeller directly driven diesel with crosshead is a proven concept, robust, uncomplicated and reliable. What is interesting is that it needs a lot of height and here it is put to the midship (I can’t see where else it could be). Normally you stack living quarters, bridge etc. in the aft together with the engine. It gives you a nice short shaft. Here the deckhouse is in the middle, no doubt because the vessel is so long they need to improve the visibility in front, but I don’t envy the guy who did the torque vibration calcs for that shaft…
With a drive thru deck, you can’t have this high engine, so if you want to know what a cargo ship without big engine looks like, a roll-on roll-off ship is a good candidate. Mostly two medium-speed diesels with reduction gear, if memory serves right.
Yes, there were a huge number of ships, with some incomplete ships as well, among them two Iowa-class battleships, the Illinois and theKentucky. They simply stopped building them at whatever point they were at in construction. Most of the Essex-class aircraft carriers were decommissioned/recommissioned at one time or another prior to their final decommissioning. All of the Liberty and Victory ships were decommissioned. We’re talking thousands of war-surplus ships in total. The scrapyards got a lot of business.
Most of them were scrapped at one point or another, or else used as targets in fleet exercises. A more recent trend is to turn them into artificial reefs, like with the Oriskany.
Yes, there is a constant program, and they frequently sit there for years before they’re scrapped. Some of them are on donation hold as well. Incidentally, there is another huge mothball fleet in California, at Suisun Bay, and the Forrestal and Saratoga are awaiting disposal in Newport, Rhode Island. There are lots of ships to dispose of.
I’m interested to see what will happen when the nuclear-powered carriers retire. They’re too big to scrap in a cost-efficient manner, they can’t be sold overseas by DOD regulation… I guess they’re all going to end up as targets eventually. What else can we do with them?
<nitpick>
It’s Wärtsilä.
</nitpick>
The Salem was decommissioned in 1959 and stayed in reserve until 1994. The Newport News wasn’t finally scrapped until 1993. Hull and machinery condition plays a part in the decision to retain, plus speed potential and general obsolescence of weapons and machinery. If nobody is left who knows how to operate the systems it gets very expensive to train new ones up.
In the 'Thirties, at least, there was a perception amongst passengers that multi-screw ships were safer to travel in and one company went to the lengths of putting frosted glass around the screw area of the model displayed in a case in their office (I think it was the City Of Benares) to disguise the fact. The model can still be seen in a museum somewhere.
My point was, even though this still happens from time-to-time, it’s infrequent enough that modern cargo ships aren’t usually built with more than one engine and screw.
“Come sail the City of Benares! It’s totally safe!”
Anchor winches do not need power to drop the anchor, just release the brake.
For years the ships in the reserve fleet were a political joke. Incase of a national emergency these ships would give us useable ships in a short time with outbuilding new. Problem is a lot of them were just towed to reserved fleet with out being sealed. The majority at one time were just rust buckets.
Now most of the junk ones have been scrapped.
I see what you mean. However, very often two engines makes no difference. Engine room fires can knock out both, or if the vessel takes on a list they both fail due to the angle etc. A vessel went aground in the UK recently for the latter reason.
I know, but in an emergency problems tend to pile on one another. Dropping the anchor on a vessel that has no power to save it running aground often works as I said, but then if the situation changes and the anchor needs to be raised, more problems can result.
All ships are required to have an emergency generator for electricity. This is not in the engine room, typically somewhere high in the deckhouse.
If it’s working after 20 years of neglect and little use.
Most ships do have emergency generators, not all do.
Ok, I don’t have the SOLAS code here so I can’t check, but I think it’s in it. So any civilian ship with (almost?) any flag will need it (above certain size?). If it’s not there then it’s in the classification society codes, so ships with an insurance will have it - still practically all.
Completely off topic, I’m afraid, but every time I see the title of this post I am reminded of this. (Link contains xkcd.)