WI Surcouf makes it to the Pacific

[La Rouge Beret]

Surcouf was a large French gun-armed cruiser submarine armed with two 8" guns and embarked a floatplane. The fact that Surcouf combined torpedos, 8' guns & a float plane seemed surreal & the model kit would make a fitting addition to my desk.

Not my build and Surcouf in 1/350 scale next to the equally impressive I 400 class submarine.

That aside Surcouf served with the Free French Naval Forces during the Second World War, but disappeared at sea in February 1942 following a suspected collision with an American merchantman.

Now, Surcouf was in the process of being transferred to the Pacific theatre, so what if her passage to Sydney was uneventful. Now with her unique armament & capabilities, how would she have been employed in the Pacific? Would Surcoufs mixed armament have found success I theatre?

 

[Sargon]

There's a book essentially about that.

Strike from the Sea by Douglas Reeman:

Causes quite a lot of mayhem for the IJN.


Sargon

 

[Driftless]

A considerable bit of handwavium, but get a prepped Surcouf to the DEI for some night time shelling of newly captured (by the Japanese) oil refineries and tankage. It would likely have been a one-way trip, but perhaps a more useful and memorable end. The Surcouf was too un-handy a sub to work for long in contested areas, plus its unique armaments and propulsion would make it difficult to keep on line.

OR,...... More plausible, keep it as a potent appearing part of the Free French Navy for showing the Cross of Lorraine flag at critical coastal colonies in Africa. I wonder the impact of seeing the distinctive surface profile has on Vichy forces during Operation Torch too?

 

[Driftless]

If the Surcouf survives into 1943, what would the inevitable and necessary refit look like? I'm assuming the Free French will want to retain the ship at all costs, at least till wars end.

Replace the troublesome engines seems very probable. Retain the French 8"/203mm (the Surcouf's identity), ? IF not, what's the replacement? The secondary/AA armament probably gets US kit, assuming the refit is in a US yard. No clue about how to deal with the unique Torpedoes. I doubt there would be a French resupply source, plus in 1943 I'm not sure the French would be keen on using US torpedoes anyways, even if the tubes could be reconfigured for them. (A) the US torpedo problem was not sorted yet, (B) reconfiguring the Surcouf's original tubes to 21" sounds...... interesting..... So, what would the French do?

 

[quillreiver]

Plate over the torpedo launchers, convert the freed up space there and the torpedo storage into space for additional passengers/supplies, turning the surcouf into a proto-special forces submarine? Hangar can be repurposed for storing boats.

 

[La Rouge Beret]

There's a book essentially about that.

Strike from the Sea by Douglas Reeman:

Causes quite a lot of mayhem for the IJN.


Sargon

Out of all the authors - Douglas Reeman - would have created a story exploring this as a WI & it's been added to my Kindle.

If the Surcouf survives into 1943, what would the inevitable and necessary refit look like? I'm assuming the Free French will want to retain the ship at all costs, at least till wars end.

Replace the troublesome engines seems very probable. Retain the French 8"/203mm (the Surcouf's identity), ? IF not, what's the replacement? The secondary/AA armament probably gets US kit, assuming the refit is in a US yard. No clue about how to deal with the unique Torpedoes. I doubt there would be a French resupply source, plus in 1943 I'm not sure the French would be keen on using US torpedoes anyways, even if the tubes could be reconfigured for them. (A) the US torpedo problem was not sorted yet, (B) reconfiguring the Surcouf's original tubes to 21" sounds...... interesting..... So, what would the French do?

This is the question that I have been toying with as well, I think reducing the radar cross section of the conning tower like the late war Fleet Boats. Although with a pair of 8' guns at the front, there may be little point tbh. Anyway, I think installing radar, improving the EW suite & perhaps adding a gun laying radar for the twin 8' guns. You could then remove the aviation facilities.

 

[Riain]

Ideally it would have been joined by the 3 RN River class and taken the war right up to Japan in December 1941.

 

[alspug]

To be honest I think the Mn Surcouf was more useful for showing the Flag. Her time to dive was excessive and her size a problem. Yes used as a special forces or special use Submarine is ideal.

 

[Riain]

To be honest I think the Mn Surcouf was more useful for showing the Flag. Her time to dive was excessive and her size a problem. Yes used as a special forces or special use Submarine is ideal.

Is excessive dive time a real problem in the Pacific? IIRC USN subs took up to a minute to dive while RN and KM boats could crash dives in 25-30 seconds, something to do with the big conning tower. But the RN and KM could expect to have a plane or escort on them at any time whereas the USN was less likely to be surprised in the same fashion.

 

[Fearless Leader]

I've looked into this WI for my ASB TL...

Another issue I haven't seen mentioned is the long time it takes for the 8 inch guns to be made ready to fire and their limited elevation. One more little tidbit is that French doctrine has them only firing AP rounds. To use them in any kind of shore bombardment role would be quite difficult and was only possible in my TL with a series of earlier changes. Even then, the guns' poor elevation and the boats poor handling made many targets off limits.

 

[La Rouge Beret]

I've looked into this WI for my ASB TL...

Another issue I haven't seen mentioned is the long time it takes for the 8 inch guns to be made ready to fire and their limited elevation. One more little tidbit is that French doctrine has them only firing AP rounds. To use them in any kind of shore bombardment role would be quite difficult and was only possible in my TL with a series of earlier changes. Even then, the guns' poor elevation and the boats poor handling made many targets off limits.

What targets did they attack in your TL?

Feel free to direct me at a specific chapter too.

 

[CaptainCalvert]

Plate over the torpedo launchers, convert the freed up space there and the torpedo storage into space for additional passengers/supplies, turning the surcouf into a proto-special forces submarine? Hangar can be repurposed for storing boats.

I think Fester had the Surcouf running supplies in the Far East, though it might have been Zheng He's timeline.

 

[Fearless Leader]

What targets did they attack in your TL?

Feel free to direct me at a specific chapter too.

Part XXVIII Footnote 18

I had them attack the Kamaishi Ironworks in Northern Honshu or at least try. The actual damage done is far less than the psychological damage which causes the Japanese to beef up their northern garrisons even more than OTL. She'll make another appearance in a subsequent update providing artillery support

Basically, I wanted something within the range of the 8-inch guns that didn't involve the Surcouf sailing into a shallow bay or confined strait due to the boat's lack of maneuverability and poor diving speed. The Kamaishi Iron Works were one of the most easily accessible shore bombardment targets for the US in OTL and one of the first targeted so they stuck out on my list. However this early attack date is only possible because of the SI averting the events of Operation Catapult which frees up the necessary 8-inch HE ammunition. There's no way that the allies would run off a small batch of shells for one mission with dubious chances of success. Heck even getting them to Pearl Harbor required a bit of handwavium. Another issue with the Surcouf's 8-inch guns was the fact that the submarine was a pretty poor gunnery platform (qeulle surprise!) so firing in anything other than calm seas would result in questionable accuracy.

I had initially planned on doing a whole story on it, but after doing some research for my other TL, I quickly realized why the MN quickly abandoned the concept (albeit much later than anyone else....)

 

[fester]

I think Fester had the Surcouf running supplies in the Far East, though it might have been Zheng He's timeline.

Yep, Bataan shuttle runs

 

[vetinari]

Surcouf lacked a very important part of mid-late-war naval warfare - RADAR. It would need at least an air-search RADAR to survive any length of time in the Pacific. For guns to be truly effective, she would need some gunnery RADAR to direct her guns. As far as Torpedoes are concerned she could be refitted fairly easily to mount American or British torpedoes. She would need an adequate AAA fit to survive in the Pacific. She is an odd boat to be sure and her uniqueness means she would be difficult to maintain unfortunately.

 

[Driftless]

With the dubious aiming(weather roll and diificult direction) a big target would be needed. Refineries, factories, that sort of thing. A small target like a moving ship or a bridge would be more difficult

 

[Draconis]

I posted a similar idea a few years back. There are some interesting comments in the old posting. But please post any replies to this new FN Surcouf thread to avoid necroing.

WI the FN Surcouf used in the Pacific War?

The French Navy's cruiser submarine Surcouf was lost in the Caribbean Sea February 1942 in unclear circumstances on its way to French Tahiti. One of the worlds largest submarines it was heavily armed with 2 8" guns main arnament plus anti-aircraft weapons. But it was ungainly as a submarine...

www.alternatehistory.com

 

[GTStinger]

Is it recorded what Surcouf’s planned use was OTL?
Was she to report to Pearl and have the admirals figure it out or was there already an assigned mission and patrol area for her?

 

[muskeg13]

Is excessive dive time a real problem in the Pacific? IIRC USN subs took up to a minute to dive while RN and KM boats could crash dives in 25-30 seconds, something to do with the big conning tower. But the RN and KM could expect to have a plane or escort on them at any time whereas the USN was less likely to be surprised in the same fashion.

What? Pre and early war USN diving standards may have been slow, but by mid-war fleet boats were expected to dive in 30 seconds or so.

Granted, USN V-Class "cruiser" subs were notoriously slow divers, but with only 9 built and commissioned in 1934 or earlier, their limited use was very small compared to over 200 Gato, Balao and Tench Class fleet subs commissioned during the war.

 

[Riain]

What? Pre and early war USN diving standards may have been slow, but by mid-war fleet boats were expected to dive in 30 seconds or so.

Granted, USN V-Class "cruiser" subs were notoriously slow divers, but with only 9 built and commissioned in 1934 or earlier, their limited use was very small compared to over 200 Gato, Balao and Tench Class fleet subs commissioned during the war.

Fair enough, I thought the USN subs had radar and could stay on the surface having a grand old time and could take their sweet time to dive.

I didn't know the late war subs could crash dive with the best of them.