In the movie Castaway, Tom Hanks is floating on his raft out in the ocean when a large freighter-type vessel lumbers into the shot. The next scene is Tom going back to civilization, the implication being that meeting this ship effected his rescue. (This thread is not to nit-pick the movie.)
OK, so what if that situation really happened? Assume a large oil tanker or container ship encounters some poor soul floating in a life raft (although not on a collision course). Assume also that there happens to be someone on the bow that sees and correctly identifies the situation.
My general question is this: What would the captain do? Would such a large ship be capable of plucking someone from the sea by itself? Or would they have to call the nearest navy/coast guard to send a rescue team?
In your answer, please address the following:
Would a big, fully loaded tanker going top speed be able to stop in enough time that they’d still be able to see the raft (behind them by this time), much less rescue the occupant(s)?
Do these kinds of ships have a small runabout they can launch and retrieve at sea?
Do they have any training/equipment whatsoever specifically meant for this type of situation? (I assume it’s quite rare for a tanker to encounter a ‘drifter’ in the open ocean, so I suspect there isn’t a lot of time & energy spent on training and equipment. On the other hand, isn’t there such a thing as a “man overboard” drill? What do they do when there’s a man overboard? Wouldn’t encountering a life raft be very similar?)
Lastly (and this is not a nit-pick, I swear!) – wouldn’t a big, fully loaded tanker going top speed and passing within a hundred yards or so of a flimsy raft maybe, uh… tip the raft with it’s wake?
IANAS (Sailor) but from what I’ve read about and surmise:
Water friction would provide for decent braking (it ain’t stopping on a dime, but everything is relative). Just cutting power could slow down the ship enough to keep the raft in sight. The crew would (hopefully) be dropping the launch and heading out for the rescue before the ship even comes to a stop. The ship could also be calling the Coast Guard or whatever organized group exists in the area (sometimes the U.S. or another nation’s Navy) for assistance.
Most, if not all, ocean going ships have some form of runabout (or “whaleboat”) available. Some harbors require ships to stay at anchor and the smaller craft is necessary to shuttle in to shore.
I don’t know for sure but training and equipment would depend on the company that runs the ship. Some probably do rudimentary instruction while others may give full classes with “hands on” practice.
Not necessarily. I did not see the movie so I don’t know what kind of raft Tom Hanks was using but many life rafts made now-a-days are designed to be very difficult to tip. A simple raft could easily be knocked about and possibly tipped over if too close to the ship’s wake, but most large freighters aren’t exactly doing 30+ knots.
Stopping a fully laden tanker can take several miles, even if they’re in a hurry to stop. They’re heavy and have much momentum, along with relatively small engines for their mass and a pretty efficient hull. Tanksers don’t stop if they can help it. OTOH, they also move fairly slowly, slowly enough that they can slow down enough for safe smallcraft operations fairly quickly.
In the book “Survive The Savage Sea”, the author details his family’s rescue at sea by a Japanese freighter which did pull alongside their liferaft and stop. Freighters, or any medium-large vessel looks freekin’ huge when you’re alongside in a smallcraft.
Assuming a reasonbly alert lookout, you might see a lifeboat in the water several miles before reaching it, allowing a fair amount of time to slowdown. A freighter, with it’s generally lower mass, is more capable of stopping than a tanker. International law requires a vessel to make all reasonable attempts to save a shipwrecked sailor. If there is a coastguard vessel or warship nearby, thay’ll mostlikely call them. Otherwise, they’ll slow down and put a boat in the water, or last resort, actually stop.
To get a sense of that realize that the largest supertanker (indeed the largest boat in the world) approaches 1/3 of a mile long (1,504 feet) and weighs in at nearly 648,000 metric tons fully loaded. That thing just does not stop on a dime. I’ve heard (no cite) that such tankers can take up to six miles to stop.
However, I think you’d be surprised at the relative smallness of the bow wake. Again I have no measurements but I’ve been on cruise ships and specifically looked at the wake the ship was leaving and it was surprisingly small. No 10-foot rollers off these babies. A small vessle would have no sweat having such a ship pass nearby (of course, if you are right next to the bow when it passes you probably will get flipped over).
That said the ship would certainly just send a lifeboat to pickup a castaway on a raft with the ship slowing sufficiently for the runabout/lifeboat to catch back up. As Tranquilis it is a rule of maritime law that a ship lend aid. Since any sailor knows they might someday find themself floating in the ocean this law is rigorously followed even if it means delays (and therefore money) for the ship. Heck, even warships usually try to rescue sailors from ships they just blew up.
FWIW from what I recall from the movie the tanker was already slowing down with alarms going off by the time it pulls up to Hanks. Wich goes with Tranquilis’s post about alert lookouts.
Just wanted to add a thought to all the intelligent replies so far:
It seems likely to me that most, if not all, ocean going vessels would maintain procedures to be used in a “man overboard” situation. Such procedures could be used for the rescue contemplated in the OP.
Do you have a cite for that? I’ve always heard that the US Aircraft carriers were the largest moving things on Earth. When I was younger it was the USS Nimitz but I think each new ship is just a little bit bigger than the last (I think it’s the Roosevelt now?)
Well, sure, under the right circumstances, but it is not a likely scenario. First, big ships go extremely fast, doing 18, 20 knots or more. At that speed any kind of maneouvering takes a lot of time. Look up the story of the Andrea Doria and you’ll see what I mean. Two ships collided after they had seen each other on radar for quite a while but they interpreted each other’s intentions mistakenly and by the time they wanted to react it was too late.
Second, they are not looking out for small things, not even for small boats. Big ships are often on autopilot and someone is there keeping an eye on things and on the radar alarm but they are not looking out for small boats. Quite a few small boats have been run down in the night by large ships and the ships never even realized it.
So the main reason a ship may be attempting a rescue is because it was looking for those to be rescued in the first place because they put out a radio call or whatever. In this case the best way would be to put a boat down but they may not have a boat or they may not be able to put it down. This can pretty much only be done in very smooth waters as the waves would just crash it against the hull.
So the only option left is to take the ship to windward and there let it drift down on to the small boat and try to lift the people. This has one advantage as the lee of the ship provides some shelter to the small boat but it is still dangerous and tricky. The waves will make the small boat rise and fall and it can be destroyed against the hull but also it can cause injury on those trying to be rescued. I have seen footage of a sailboat crashing against the huge hull of a freighter. There is no way you can rescue someone under those conditions as he will probably be mangled by the mast. Even on an inflatable, the person would have to grab the ladder when on the top of the wave and then let the boat fall from under him. It can be done but it is not easy.
Even on small boats which are much more maneouverable, picking up someone is a difficult task. If the person is conscious and can help, the easiest way is to trail a line and circle the person. When that person has grabbed the line and tied it around himself you haul him on board.
I have some friends sailing in the Caribbead these days and they recently rescued some diver who had been lost by his boat. My friends could not haul him onboard and they kept him alongside in the water and called for help.
Meet the ULCC, or Ultra-Large Crude Carrier. This particular one is:
333 meters long (or 1032 feet),
Has a design draft of 52 feet (max draft: 59 feet),
Has a design deadweight* of 268,000mt (max: 314,000mt).
Now meet the USS Lincoln, CVN-72 (the most recent vessel of this class, the USS Ronald Reagan, is somewhat lighter):
Length of 1092 feet,
Max draft of 42 feet,
and has a design deadweight of 22904 tons (Max displacement is about 104,000 tons)
Excepting for length, the ULCC has a Nimitz-class carrier completely beat for size.
sailor, you may want to take note: Max speed at design draft for the above modern ULCC is under 17 knots, while max possible speed is under 18 knots. Tankers just don’t move all that fast. Older tankers move more slowly, in general, but smaller ones may move somewhat faster.
In the end, it’s about power-to-mass. Smaller tankers tend to have better power-to-mass ratios, and so can go more rapidly than the ultra-large brutes, but they can also back down faster, too. It evens-out in the end. Tankers go at the fastest economical cruising speed, which is somewhat below max speed for their draft. The problem with stopping one is not speed, it’s about the ability to put energy into the water in proportion to their mass. Warships, with their very powerfull engines and reatively low mass are far more capable of stopping in short distances. When it’s all said and done, any rescue at sea is low probablility. The sea is a vast place, and a life boat or raft is a damned small target.
deadweight is the difference between light displacement and max displacement, and equals to the vessel’s carrying capacity.
To second what sailor said, these larger ships are essentially on auto-pilot on the deep ocean. Someone must stay at the helm, of course, but unless they’re in a heavily-travelled shipping lane or close to port, they probably won’t post a watch. It is unlikley that a freighter or oil-tanker would spot a small raft on the open ocean unless specifically directed to watch for one- and even then, unless the raft has a color that contrasts very well with the ocean and sky, the chances are almost nil that an active, untrained watch would spot the drifter. Okay, assuming that a raft was spotted, the very first thing that would happen is a position report. Whether or not the large ship could affect a rescue, the authorities would have the raft’s last known position. Close enough to land, and a helicopter is dispatched. Too far? The closest ships would be directed to assist, i.e. the one that spotted the raft. Whether the ship can stop on a dime or not, I don’t think the ship would abandon the raft until the survivors are rescued. That’s just the code of the sea.
There are lots of great books about survival at sea (and survival in general) that you should read: Desparate Journeys, Abandoned souls or Adrift are two that immediately come to mind.
On American-flagged vessels there is usually an Able-Bodied Seaman at the helm along with the Mate in charge of the watch are on the bridge and depending on where the ship is there might be another AB posted as lookout. If they are out in the middle of the ocean then they aren’t usually too concerned with small craft. If they are in the shipping lanes and especially places that have a lot of traffic like the Straights of Malacca, then they will be very vigilant.
May not have a boat? Ships carry lifeboats and are trained in launching them. The AB’s will have a lifeboat endorsement from the Coast Guard. Fire and boat drill is carried out once a week by law. The captain isn’t going to risk his crew in rough seas but they can drop a lifeboat if it’s safe enough and that isn’t just in glassy seas.
As far as coming back on its wake the ship can use several different maneuvers…the Williamson turn, the Scharnow turn or the single turn. The Williamson takes longer but is more likely to return you closer to the spot you want to be. During the time this takes to complete, someone will be designated to try to keep the victim’s life raft in sight. All hands will be called to man their lookout stations. All in all it isn’t an easy thing to pull off especially in ships that enormous.
Acceleration and deceleration are about power-to-mass. Top speed is more complicated. A ship is said to have a “hull” speed – the top economical speed. It’s proportional to the square root of the waterline length. The popular explanation is that when a ship tries to go faster than its hull speed, it is struggling against the waves it is creating, which requires a large increase in power for a small increase in speed.
The result of this is that larger ships tend to go faster. It’s not that you couldn’t make a smaller ship match the speed of a larger one – it’s just that the engines required would be unnecessarily large and expensive. Merchant ships almost always care about economy.
Warships are different. They are not as bound by concerns for economy, and tend to have much larger engines in proportion to their size. I was on a destroyer that could do 33 knots at full power – way above its hull speed. The fuel required to do this was astonishing. IIRC, with full fuel our endurance at 15 knots was around 14 days; at 33 knots it was something like 10 hours.
>> On American-flagged vessels there is usually an Able-Bodied Seaman at the helm along with the Mate
“Usually” is the operative word here. What should be done and what is foten done are different things. Remember the Exxon Valdez? The fact that there is someone standing by does not mean the ships do not have autopilots and use them
Dropping a boat while underway or in rough seas would be extremely dangerous but I never used the word “glassy”. I am not certain about the carrying lifeboats part. I have definitely been on ships that had no boat at the time (but this does not mean it was legal). I thought liferafts were required, not lifeboats. You cannot practice with liferafts as they have to be sent back to the manufacturer for repacking.
>> I was on a destroyer that could do 33 knots at full power – way above its hull speed
It has always been my understanding that a ship driven over the hull speed would start to plane which I am quite sure a destroyer will not do. Can you provide any cites showing ships can exceed their hull speed while remaning in displacement mode? The destroyer USS O’BRIEN is listed as LOA 563’ and Max Speed 30+ knots. It does not specify LWL or what 30+ is. At any rate it is not over hull speed but more probably it is hull speed.
Thinking about this I would say it is not possible for a ship to exceed hull speed without either planing (if deflection forces push it up) or submerging (if deflection is greater downwards).
Go back and check the info I linked to. Tankers are relatively slow, and have fat, blocky hulls.
I’ve deliberately stayed away from things like hull form, “fineness”, surface area, hull condition, water conditions, length of waterline, and a host of other considerations that affect speed, as we’re not debating naval architecture.
Tankers have small engineering plants for thier size, and sail below their hullspeed, but even still, if the plant is too small, it’s not going to go even that fast. The ability to slow to a safe speed for smallcraft ops is what’s at consideration here.
And yes, some military vessels can exceed hullspeed, if they need to, and yes, it requires a God-awful amount of energy to do it. Instead of sliding through the water, they’re bulling the water out of the way. It’s grossly inefficient, but it can be done.
Tranq
15-year Navy Veteran
Sailor, “usually” was the wrong choice of word on my part. The fact is there is always an AB at the wheel regardless if the ship is on auto-pilot. And there is always a licensed Mate on the bridge and in charge of the watch.
Ships the size of supertankers (VLCCs, ULCCs or Suezmax) will carry both lifeboats and cannister type life rafts. I believe that the lifeboats on ships carrying flammable cargos have to be aluminum hulled instead of fiberglass.
But to answer the OP here are two versions of a rescue that will clear all doubt as to whether tanker crews can pull off a rescue at sea:
>> And yes, some military vessels can exceed hullspeed, if they need to, and yes, it requires a God-awful amount of energy to do it. Instead of sliding through the water, they’re bulling the water out of the way. It’s grossly inefficient, but it can be done.
Well, I’ve never heard of it and I’d like to see some proof. The link I gave shows a destroyer which cannot exceed hull speed. can you show me one that can? I’d just like to see it as I have never seen it. Can you give me some cites?
