What are these things?

amphib

Not sure what you were supposed to do if you caught one.

Well, during WWII, test depth was only about 100m/300' for all the submariners.  That's only 50 fathoms of anchor out.

And, WWII subs are covered in fragile stuff on their topsides.  Hydrophones, sonar emitters, dive planes, periscopes & antennae just to start.  The periscope shears are particularly vulnerable.  Give them a snag with a 20,000 bower ancher and it does not take a lot of misalignment to start letting seawater into the boat.  Blind and sinking is not a good submarine combo.

One thing I noticed missing from all the paravane instructions was just what one was supposed to do with the 30-50 fathoms of plow steel sweep wire once you were no longer streaming it.  This is 1.5" to 2" wire rope, which will want oiling/greasing to keep it from rusting.  It's about 5#/lf, so 50 fathoms is 1500#, 3/4 of a ton (circa 7.5kg/m, so 100m is 750kg or about 0.75tonnes). 

Not something I want to wrestle on a pitching foredeck, but also something that can't be allowed to rust out on deck, either.  Which means I have to get the deck apes to strike this stuff below somehow.  And in a way that can be brought up on deck and bent into the paravane tackle in an expedient and seamanlike manner.

Those old publications have some interesting information in them. The ship I was on had a technical publication library that had some (I hope) obsolete advice such as lowering anchors while underway to "troll" for enemy submarines that might be hiding under a convoy. Not sure what you were supposed to do if you caught one.

Ship conversions always seem to leave funny "odd" bits about.  Part of both the charm, and the frustration, in modeling such.

In going through my old references, there are a number of cautions for commanders of multi-ship squadrons on setting up paravane sweeping.  Like staggering the ships so that the "belly" of the catenary of the sweep wire would align with the centerline of the ship abaft.  (Note that the lead ship sweeping has a rather a large "vulnerable" zone along that ship's centerline.)

That's what they look like.  This is the hasegwa 1/350th scale kit and it has two on each side.  According to the history included, the Akagi was at one time a battlecruiser converted to a carrier.  During the conversion she gained 10,000 tons, bringing her up to 46,000.  Many things were kept from her old days, but there were many changes like the ability to carry 90 aircraft  if necessary.  When you look at the sides there are supports, curves and angles all over.  I started calling her the I.J.N. afterthought. It's like they started the conversion and as they went along at various points they realized they they needed to add more supports or something else. There are search lights mounted under the flight deck, on one side, and even some on the flight deck.  Even its main guns don't match up.  It has three turrets on one side and three open cannons on the other and there were six pivot cannons near the stern.  What a beast. 

As others have said, I would guess paravanes. Don't know of anything else that fits the description that would be on a ship's deck. The USS Lenawee APA model I built had a couple on the forward part of the superstructure, on the boat deck near the No. 2 hatch.

The old ‘50’s movie “Away All Boats” has a good scene regarding paravanes and sailing thru a mine field during the Philippines Leyte or Luzon landings period.

Paravanes.

Designed to haul a sweep wire out away from the forefoot of a ship.  The sweep wire would collect the lines on moored mines and pass them to a cutter at or near the paravane.  The mine would float to the surface out near the end of the sweep, where it was meant to be dealt with by small arms fire (shot until sunk).

Paravanes became de rigeur after the Washingto Naval Treaties.  The compromises in ship size, but also quantities of ships in classes made it necessary to be able to self-sweep.

All USN combatant vessels cruiser-sized or larger carried them.

During the 30s, it was considered a matter of naval prowess to be able to stream paravanes, with careers hanging in the balance in getting the things over the side and back again.

Actual wartime use appears to be nearly nonexistant. 

One for the lack of tactical reason to steam through minefields. 

But, mostly, becasue, during the 30s, everybody added non-moored influence mines.  Paravane has no effect on magnetic or acoustic mines.  And capital (cruiser or larger) ships were the specific sorts of targets influence mines were meant to go after.

Add in that many of the wartime officers all too well rememmbered the angst and rigamarole around peacetime paravane streaming and eschewed it for just that reason.

But, since they were issued to the ship, you couldn't really leave them ashore.

keavdog

Ohka?

 

Not on Akagi,sunk in 1942

I believe the mine sweeping answer is correct,thought I read that somewhere.

Hi ;

 Looking through a magnifier I would say Paravanes . I could be wrong . T.B.

Paravanes may have been standard equipment on all ships expected to go in harms way during WWII. The APA I was on had them at one time. They were long gone but the small cranes to deploy them were still there port and starboard. We used them to raise and lower the accommodation ladders in the 1960s

keavdog

Ohka?

 

Akagi was long gone to the bottom of the Pacific by the time that the Okha appeared.

GMorrison

EDIT: I seem to remeber that a few of the early USN carriers like Lexington and Saratoga had a set up with booms at the bows that would trail mine sweeping cables, but that was abandoned. And they were also converted battle cruisers like Akagi. 

Hi,

On the topic of paravanes in general, I believe that at least some US battleships may have also carried them, as shown in this image of the USS Texas from Wikipedia.  Maybe since battleships, and other big gun vessels, were expected to often sail and/or operate in a battleline, paravanes might have made sense for them.

Pat

EDIT:  Ooops, I also just found this link which appears to indicate that paravane gear is included in the Specs of the CV-9 Essex class - Spec so maybe they may have also been included on other carriers as well

Ohka?

Ikar a photo would help. I think PJ is right, but an aircraft carrier using paravanes would be pretty unusual.

A paravane is a towed bouy that is at the end of a mine cutting cable. That operation depends on the low probability of a narrow ship actually hitting a mine. DEs, DDs and light cruisers might do it, but a big wide ship like Akagi would probably never venture into a known or suspected mine field.

It's a sweeping operation, not a protective measure for the ship.

Show us a pic, otherwise not sure.

Bill

EDIT: I seem to remeber that a few of the early USN carriers like Lexington and Saratoga had a set up with booms at the bows that would trail mine sweeping cables, but that was abandoned. And they were also converted battle cruisers like Akagi.

Hi,

They may be paravanes, which (I believe) are bodies towed by a ship to help sweep away mines.  This picture from Tamiya shows some on a Japanese WWII Detroyer.