Destroyer hooks

[Schultz]

I recently saw the movie "Below", and that a german warship being out of depth charges used hooks.Now comes the question did american or british ships had hooks?

[Dread Knot]

The Japanese did experiment with such a device..


At least two types of anti-submarine explosive weapons designed for underwater tow by small surface vessels are known to have been developed and used by the Japanese, particularly early in the war. The first of these was called the "Yokosuka depth charge," and was set to explode upon contact with a submerged object. The charge was cylindrical in shape, about 1 foot in diameter by 5 feet in length, and contained 55 pounds of Type 88 explosive filler.

The second weapon was designated by the Japanese as the Mark 2 Explosive Hook and, although developed primarily for minesweeping, was occasionally used for anti-submarine work. This device was a cast iron cylinder, 8 inches in diameter and ten inches long with four grapnel-like arms projecting from the main body, each 71/2 inches long. The body contained a charge varying form 8 to 19 pounds of Type 88 explosive. Firing was accomplished after the hook secured on a submerged target; the Mod. 0 either electrically by an observer on the towing ship or automatically when an additional tension of 550 pounds was put on the towing line, and the Mod. 1 by electrical control from the towing ship. Although several reports were received from U.S. submarines of small Japanese vessels apparently using these two weapons, no large-scale employment was made and there is no information to indicated that damage was ever inflicted.


From hyperwar
http://ibiblio.org/hyperwar/USN/rep/WDR/WDR58/WDR58-3.html

As far as I know, the Germans and Americans never did.

[Sailor Steve]

Submerged Type VIIc uboat displaces almost 1000 tons. British 'J' class destroyer displaces 1690 tons. Destroyer hooks uboat while it's diving:

1) Hook snags outer hull of uboat and rips a hole that really won't affect the boat other than slowing it down a bit due to the jagged edges.

2) Hook snags something solid and destroyer suddenly finds itself attached to 1000 rapidly sinking tons. Kind of like deep-sea fishing and snagging a whale.

[Schultz]

Thats what happend in "Below" a hook snatched the coning tower until the periscope tubes bended and cracked so they had to clear the coning tower beacause of the water.
Here are 2 ss of the hooks.
http://img114.imageshack.us/img114/7816/67351153.jpghttp://img382.imageshack.us/img382/5113/23358852.jpg

[Sailor Steve]

My point was that they wouldn't do it because there's a perfectly good chance that the sub might drag your destroyer down with it.:dead:

[Schultz]

The point is that in the movie the sub was already at the bottom :haha: so the hooks were long enough to reach the sub. Maybe they should put this on sh5 .

[FIREWALL]

My point was that they wouldn't do it because there's a perfectly good chance that the sub might drag your destroyer down with it.:dead:


Your saying it was never tried in RL back then ?

[Letum]

I'm not so sure Steve.

The Sub may displace 1000 tons, but it' weight in the water with tanks
flooded will be far, far less than 1000 tons. At neutral buoyancy the weight
will be zero.
I would be surprised if the basalt tanks could get more than 10 tons extra
weight, but I could certainly be wrong.

[Platapus]

2) Hook snags something solid and destroyer suddenly finds itself attached to 1000 rapidly sinking tons. Kind of like deep-sea fishing and snagging a whale.


" Brody (http://www.imdb.com/name/nm0001702/): You're gonna need a bigger boat.":D

[Sailor Steve]

I'm not so sure Steve.

The Sub may displace 1000 tons, but it' weight in the water with tanks
flooded will be far, far less than 1000 tons. At neutral buoyancy the weight
will be zero.
I would be surprised if the basalt tanks could get more than 10 tons extra
weight, but I could certainly be wrong.
As I understand it a basketball filled with air weighs more on the scale than a deflated one, but I might be misremembering.

In any case, the mass will be the weight of the boat plus the weight of the water on board, so the submerged displacement will indeed be much more than the surfaced displacement.

And if the boat is headed downward at the time of the snagging, you will also have the momentum added into the equation.

All I know for sure is that the Japanese experiment describes a bomb attached to the hook, and that the Allies didn't do it as a matter of course.

[Letum]

In any case, the mass will be the weight of the boat plus the weight of the water on board, so the submerged displacement will indeed be much more than the surfaced displacement..


I think you might be confusing mass and weight.
The mass of the boat is the mass of the boat and the basalt, however
the weight of the boat is the mass of the boat minus the mass of the
water displaced multiplied by the force of gravity (this value is always 1 on
earth so we can ignore it).

When any boat is not sinking or rising it's weight is zero because the
mass of displaced water is equal to the mass of the boat.

When a boat is sinking that means it's mass is greater than the mass of
the water displaced. In a u-boat the weight of the boat can not exceed
the spare capacity of the basalt tanks after they are filled to neutral
buoyancy.

The VIIC can change it's weight by about 135 tonnes (2x 25m^3 tanks,
2x32m^3 tanks and the ~20m^3 tank ) and can change it's displacement by 118 tonnes.

That means that the VIIC will never weigh more than ~16 tonnes in water.
Under normal operation this value would likely be a deal lower than 16 tonnes.

You are quite right to worry about momentum tho.
Momentum is a product of the mass of the two boats and not the weight.

The sun, for example, has almost no weight, but plenty of momentum.

[Dread Knot]

I think using a rather improbable movie like 'Below' as a basis for which ASW devices to include in SH5 would be a detriment to the sim. It's the only sub movie I can think of which rivals U-571 for historical inaccuracies.

[SteamWake]

My point was that they wouldn't do it because there's a perfectly good chance that the sub might drag your destroyer down with it.:dead:

Surely they would have some sort of emergency release, what if the hook snagged a reef then you would be stuck :06:

[Letum]

A net might be a better idea than a hook.

Trawl a large steel or rope net between two ships.
When you catch a sub, release the net along with an anchor attached to it.

[Subnuts]

Hey guys,
It's a movie.

Maybe they should include a Russian submarine captain with a Scottish accent, a dog that pisses all over the boat, destroyers that explode deck-first in enormous fireballs, a first officer that disagrees with everything you do, and a token black guy into SH5, too.

[Webster]

a year or two ago we had a long discussion about this (i think it was in sh4 mods forum) and with all the data found, it was clear that sub hooks were made and used (i cant remember if both sides tried it or not) but after several types were tried they found it was more likely the destroyer would in most cases recieve more damage than the sub and if it snagged the bottom it was almost a certainty that the DD would be sunk or have its stern severely damaged.

the only time they found records of use of the hooks were almost exclusively used in harbors and protected ports. the reason the idea came up was because DD would often damage themselves in shallow water depthcharging so a better safer way was wanted to damage subs in shallow water.

the testing they did found that dragging just the cables would often work better than using them with the hooks because the cables would often cut into sub hulls enough to cause more flooding or foul the subs rudder or propellers, but it did this without severely damaging the DD at the same time.

dragging just the cables was looked at as a better solution than using hooks but in the end the whole idea of dragging anything was decided to be less effective and more dangerous then just have DD go faster when dropping depth charges so they could avoid the shock wave.

now this thread was like 2 years ago and i have no links or data to back all this up so if you want to say im wrong or argue the point then just ignore what i've said on the subject but the guys in the discussion had facts and links to back up what they were saying and knew what they were talking about.

[tater]

IT's not like the cable would snag and harm either. The whole idea is that when it hit, the escort hears it, and can prosecute the attack.

[FIREWALL]

If harbors then were as polluted as they are now the, Stink alone would have scared a sub outta there. :har:

[NoLine]

This reminds me off this (http://news.bbc.co.uk/2/hi/europe/4378899.stm) story.

Noline

[Jimbuna]

I seem to recall the Japanese tried it on occasion but have never heard of the allies following suit :hmmm:

[Sailor Steve]

I think you might be confusing mass and weight.
Possibly. It wouldn't be the first time.

When any boat is not sinking or rising it's weight is zero because the
mass of displaced water is equal to the mass of the boat.
So if a diver came upon the submerged sub, he would be able to push it as if it wasn't there? Or if a fisherman snagged it he could just reel it in? That doesn't sound right to me. The thing still has the same mass, and any attempt to hook it is going to meet with that many tons of resistance.

[Schultz]

I one of the hooks catches some holes of the hull of the sub it would just rip it apart, how it happend in the movie

[Letum]

So if a diver came upon the submerged sub, he would be able to push it as if it wasn't there? Or if a fisherman snagged it he could just reel it in? That doesn't sound right to me. The thing still has the same mass, and any attempt to hook it is going to meet with that many tons of resistance.

It's not the weight that would stop him, but the momentum and drag that
would make is difficult to move the sub fast. However, the diver would
theoretically be able to get the sub moving with virtually no effort, just very
slowly at first because of the momentum/inertia and then not reach a high
top speed because of the drag.
The weight of the sub would not be an issue as it has no weight in the
water at neutral buoyancy. Inertia and drag would be the big issues.

[Webster]

IT's not like the cable would snag and harm either. The whole idea is that when it hit, the escort hears it, and can prosecute the attack.


actually tater that was exacly what happened, they had to pull them faster than a trawler does so the hooks would hook into the hull and not slide off.

they couldnt use depth charges which was rthe reason for the hooks not as a detection method but they were meant as an offensive weapon of their own.

DD would often go too fast by using the same running attack tactics as if they were depth charging so when it snagged something then something was ripped off, either the subs hull or the DD rear deck was damaged. the winches were literally ripped off the decks along with everything it was attatched to and all the rigging for them and it often messed up the decks to the point repairs couldnt be avoided. in one case the DD snagged the rockbed and it was badly damaged.

if DD went too slow then subs could easily move out of the way by going to flank since they were noisy and im sure they could hear where the hooks were dragging. another drawback was the rear racks were removed so you lose those as weapons and trawlers didnt have enough mass to do the job so they werent a good choice to use the sub hooks.

its not like dropping a trawl over the back end and tying it to a moring cleat.

[othr]

Imagine the submarine as a very big paddle. VERY big paddle, now imagine the said diver try and paddle with it.

[Sledgehammer427]

I don't they would try to "catch" the sub.

IIRC the japanese would "Hook" a sub and let go of it, buoy attached. that way you can watch exactly where this sub is going, and there was even some oddball way to tether a pole (with buoy) to it and guess within a few feet how deep the sub was.

[Hartmann]

I´s better use a giant net with some explosive devices attached to it

:haha:

[Jimbuna]

Now we know where they got the idea to track jaws from :hmmm:

:DL

[The Bandit]

I will have to look up the incident specifically but as I recall some of our RCN guys in WWII did something kind of similar. They were low on DCs and they had a Uboat pinned so they dragged a DC on a chain with some kind of contact detonator if I recall correct. As far as I remember it worked and after detonation they had debris coming up to the surface. I will have to go through my books to find the exact incident.

[Jimbuna]

I will have to look up the incident specifically but as I recall some of our RCN guys in WWII did something kind of similar. They were low on DCs and they had a Uboat pinned so they dragged a DC on a chain with some kind of contact detonator if I recall correct. As far as I remember it worked and after detonation they had debris coming up to the surface. I will have to go through my books to find the exact incident.

That sounds very interesting.....hope you find the reference http://www.psionguild.org/forums/images/smilies/wolfsmilies/thumbsup.gif

[Hitman]

IIRC from what I readed in books about WW1 some time ago, the real objective of the towed hook was to try to desestabilize the submarine by lifting a part of it. That could be enough to make it lose trim and plunge to the bottom uncontrolled. Apparently this effect was caused also by close placed depth charges: If a part of the boat was lifted abruptly, it lost trim and went down. :hmmm:

[IanC]

Sounds like ideas that should work on paper, but probably never did in practice.

[Mittelwaechter]

http://www.anzacsite.gov.au/5environment/submarines/ae2.html

Hooks and Hands!

http://www.subsim.com/radioroom/images/smilies/icon_biggrin.gif

[ETR3(SS)]

Hey guys,
It's a movie.

Maybe they should include a Russian submarine captain with a Scottish accent, a dog that pisses all over the boat, destroyers that explode deck-first in enormous fireballs, a first officer that disagrees with everything you do, and a token black guy into SH5, too.
This.