# U-Boat Attack Warning



## beedeesea (Feb 28, 2006)

"The Irish Oak (going to Ireland) exchanged a greeting with the Irish Plane (going from Ireland) as they passed. Perfectly normal. But there was a message in the message "Frank is aboard for this voyage". The radio operators on the ships in the convoy would hear the exchange and understand its meaning."

The above is an excerpt from a posting on a local web-site, concerning the sinking of the "Irish Oak" during WW2. In dealing with the issue of whether or not she had issued a warning of U-boat activity to a British convoy in the vicinity, a survivor stated that this was a method of warning them "informally", without appearing to do so. Sounds a bit far-fetched to me........any of you ever hear of anything in that vein?

Regards,

Brian


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## Boatman25 (May 17, 2010)

Yes I have, my Uncle was on North Atlantic Convoys in the war and he told us they used to talk like that between the ships and that the escorts listened in and could get a warning without the submarines on the surface preparing to attack knew that the escorts knew


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## sparkie2182 (May 12, 2007)

The R.N. "equivalent" was the use of high speed aldis signals ship-ship

Even if an enemy periscope was fortunate enough to see the flashes........there was no way they could be read.........in this manner plain language could be used, thereby avoiding the need for of time-wasting code/decoding.


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## Troppo (Feb 18, 2010)

What about radio silence?

Ships in convoy were under _strict _instructions not to tx unless it was a distress...


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## sparkie2182 (May 12, 2007)

Quite.....hence the aldis.


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## Moulder (Aug 19, 2006)

..... and the occasional hoisting of flags.

(Thumb)


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## CEYLON220 (Feb 19, 2006)

Moulder said:


> ..... and the occasional hoisting of flags.
> 
> (Thumb)


My old memory is`nt so good these days but when we were on exercise (peace time) and a contact was made of a submarine being in the area a black flag was hoisted(day light time)to alert the rest of the fleet on exercise, I suppose the aldis lamp was used at night instead of radio.


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## King Ratt (Aug 23, 2005)

Regarding Sparkie2182's comments on High Speed Aldis surely the limiting factor would be the retentivity of the eye? Any ideas how many words per minute could be sent before this rendered visual signalling impossible?


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## sparkie2182 (May 12, 2007)

I recall a friend of mine in the "seaman" branch relating how to him, it often seemed like a virtual stream of light with merely a variation of intensity.
Nevertheless, a repeat was rarely requested.

The following interesting site on the Royal Canadian Navy quotes 13 w.p.m. as being the norm.
Considering audio morse begins to be considered "commercial" at 18w.p.m....... that is good going.

Another point to note is the range............in favourable conditions of low cloud, 80 miles has been recorded which overcomes even the curvature of the earth limitation which V.H.F radio has to contend with.

http://www.jproc.ca/rrp/rrp2/visual_lights.html


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## King Ratt (Aug 23, 2005)

That is an interesting article, Sparkie2182. RFAs carried the carbon arc projector at one time as well as the other signal projectors. I only once remember it being used for VS off clouds and that was over a distance of 30 miles. 
Regards
KR


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## beedeesea (Feb 28, 2006)

Troppo said:


> What about radio silence?
> 
> Ships in convoy were under _strict _instructions not to tx unless it was a distress...


Irish/Neutral ships didn't observe radio silence.......hence the convoy escorts could listen in and pick up any coded phrase being transmitted. Not sure how the codes were agreed in advance, or at what level (official or unofficial) they were organised, however.

Brian


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## Coastie (Aug 24, 2005)

beedeesea said:


> Irish/Neutral ships didn't observe radio silence.......hence the convoy escorts could listen in and pick up any coded phrase being transmitted. Not sure how the codes were agreed in advance, or at what level (official or unofficial) they were organised, however.
> 
> Brian



Surely it would have had to have been agreed unofficially as Eire was neutral therefore could not be seen as helping the UK or that would have drawn them into the conflict?


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## beedeesea (Feb 28, 2006)

Coastie said:


> Surely it would have had to have been agreed unofficially as Eire was neutral therefore could not be seen as helping the UK or that would have drawn them into the conflict?


Yes, that's what I'd like to know; who agreed what with whom?

Brian


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## Binnacle (Jul 22, 2005)

beedeesea said:


> Irish/Neutral ships didn't observe radio silence
> Brian


Irish Republican ships, if they wished travel in a British convoy, had to comply with British regulations and AFAIK had to carry a British clearance certificate (Navicert) which had to be produced on demand, They were subject to Admiralty restrictions, including radio transmission. All neutrals were subject to British blockade rules. which included inspections of cargoes and movement.


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## beedeesea (Feb 28, 2006)

Binnacle said:


> Irish Republican ships, if they wished travel in a British convoy, had to comply with British regulations and AFAIK had to carry a British clearance certificate (Navicert) which had to be produced on demand, They were subject to Admiralty restrictions, including radio transmission. All neutrals were subject to British blockade rules. which included inspections of cargoes and movement.


"These experiences and the inability of the Royal Navy to protect merchant ships had a most profound effect on all Irish Ships. Ship-owners, on the advice of their masters, decided not to sail their vessels in British convoys and by the early months of 1942 the practice had ceased."

In the instance quoted above both the "Plane" and the "Oak" were travelling alone.

Brian


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## kewl dude (Jun 1, 2008)

re light signals reflected by clouds

Once upon a time I had up on Geocities the first person WW II account of Captain Jarvis Master of the Liberty Ship Adoniram Judson. 

Quote

Adoniram Judson departed Manila with orders to clear with the Leyte Control office for routing to San Francisco. We departed Leyte Control station for San Francisco with a stop over in Kwajalien for bunkers at 1800 on August 9, 1945. 

At 2230 on August 9 we saw our call sign in the sky. When we tried to answer with our signal lamp and received no reply, we knew we had seen Leyte control signal reflected off a cloud. At this time I turned the ship around and retraced our course back to the Leyte Control station arriving there at 0430 on August 10, 1945.

When the Navy boarding officer came aboard at 0530 on August 10 with new routing we were informed that the Cruiser Indianapolis had been sunk by the Japanese just off the northeast coast of Samar. We were given new routing which would take us to Palau for bunkers then to San Francisco. 

We departed Leyte Control station at 0630 on August 10, 1945 for Palau Island. SS Adoniram Judson was just entering Palau harbor at 1200 on August 14, 1945 when all the Navy ships began sounding off. The Palau control station gave us orders to go alongside an oil tanker for our fuel. When we tied up along this tanker we learned the Japanese had just surrendered. 

The vessel took on 4,000 bbl fuel oil and departed Palau at 1800 August 14, 1945 for San Francisco. What a relief to be able to sail with navigational lights on once more. No need to keep deck house port holes closed and blacked out. One could open the port holes and get some air circulation through the living quarters once again. SS Adoniram Judson arrived in San Francisco mid September 1945 and the crew was paid off.

Unquote

Left image attached Captain Jarvis, right, accepting Gallant Ship Award for Adoniram Judson in 1946. Right Captain Jarvis at age 90 in his home office. Behind him the latest in his large collection of sailing ships Captain Jarvis built over the years. Captain Jarvis built his ship models the same way the ships themselves were built. Laying the keel then building the skeleton then planking the hull, etc. Captain Jarvis also had a nice collection of model boats he built in bottles.

Greg Hayden


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## RayL (Apr 16, 2008)

beedeesea,

I take your point that it would be interesting to know how the prearrangement was instigated and implemented, but I'm sure you will agree that the idea was a good one.

A few years ago I took a part-time job in a hospital and had to attend an address given to the staff by the Security Officer. He told us that if we were ever in a duress situation and the phone rang, we should say to the operator "Please could we have tea for two?" This would be fully understood as a request for rescue.

I also think of the cunning device developed quite late in the war when we had centimetric radar. Circuitry was added so that a Catalina approaching a U-boat would have its radar power progressively diminished to make it appear to the U-boat that it was receding. What a shock for them when it suddenly appeared in the sky and swooped! These tricks were what it took to win a difficult war.


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## IAN M (Jan 17, 2009)

If a British or Allied merchant ship came under attack, the radio officer preceded his distress transmission with SSSS, AAAA, RRRR or QQQQ according to whether the attacker was a submarine, aircraft, unidentified warship or raider.


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## Coastie (Aug 24, 2005)

beedeesea said:


> "These experiences and the inability of the Royal Navy to protect merchant ships had a most profound effect on all Irish Ships. Ship-owners, on the advice of their masters, decided not to sail their vessels in British convoys and by the early months of 1942 the practice had ceased."
> 
> In the instance quoted above both the "Plane" and the "Oak" were travelling alone.
> 
> Brian


I'm not really surprised. Travelling in a British convoy made them prime targets, surely?


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## sparkie2182 (May 12, 2007)

On the other hand, how many U-boat Captains would ask questions?


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## chadburn (Jun 2, 2008)

Ships sailing in Allied Convoy's were boarded by Boarding Officer's, they would "indoctrinate" the Master into what was required of them, the Master would sign the "Certificate of Readiness" (see my photo's) at which point he will receive a "Sailing Order Folder" which contain's all the information he needs to know regarding his NCS voyage.


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## beedeesea (Feb 28, 2006)

Coastie said:


> I'm not really surprised. Travelling in a British convoy made them prime targets, surely?


Coastie,
Looks like they learned that the hard way!

Brian


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## beedeesea (Feb 28, 2006)

RayL said:


> beedeesea,
> 
> I take your point that it would be interesting to know how the prearrangement was instigated and implemented, but I'm sure you will agree that the idea was a good one.
> 
> ...


Yes, RayL, as you say a nice idea, and I'd love to know how they set it up. Interesting about the Catalinas; had never heard that before.

Brian


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## beedeesea (Feb 28, 2006)

sparkie2182 said:


> On the other hand, how many U-boat Captains would ask questions?


Sparkie,
Some U-boat captains would appear to have not been overly-fussy about the nationality of the ships they attacked.

Brian


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