Does anyone have info on the RN numbers for this design?

Also any drawings / photos of the 40mm Bofors as fitted to this craft.

Regards

Martin

Hi Martin

I'm afraid you have me stumped, I can't think what the number 2422 refers to, and I can't think of a Thornycroft MTB fitted with a 40mm Bofors. Sorry to be so useless, can you give us some more pointers please?

Do you mean a post war Vosper-Thornycroft design?

A Brave perhaps? Brave Borderer was P1011 and Brave Swordsman was P1012. These vessels carried one 40mm Bofors when configured as MTBs and two 40mm Bofors when configured as MGBs.

Regards,

Hello Martin - Welcome aboard!

Christian has covered my original thoughts on your question - just maybe I thought - were you refering to MTB's 24 and 22 ? - one of those (24) being a Thorneycroft - but to shoot that idea down in flames - 22 was an early Vosper. The 40mm Bofor - the only images that I have seen has shown several armament profiles including 20mm single and twin Oerlikon's - but - not a 40mm Bofor - that does not rule it out however as I have spoken with a Veteran (2nd) Officer - who was involved in early trials with a Bofor (in the Med - yes trials in the Med!) on an ML - not very successful evidently - first shot very much 'over' - second shot 3 feet off the Port side . There is an excellent line drawing of the Mk 3 Bofor, as used by the US Navy, in John Lambert and Al Ross's work "Allied Coastal Forces of WW2" Volume 1.

I'm sure that somebody may be able assist you further Martin - keep popping back

Regards

Ted

Hi Ted

As an aside, the 40mm US Army Bofors was used in service on RAN Fairmiles against the wishes of the Admiralty who wanted them to use various 2 and 3 pdrs, they however proved very successful despite their relatively slow laying and training rates.

I got this snippet from Fairmile Ships Of The RAN Vol I, a good read.

Cheers, 

Hi all,

Thanks for all the comments.

A little more.

According to Thornycroft drawings the RN numbers 24, 25, and 28 were allocated; but clearly as dated Nov 1939, not confirmed. Now there is evidence that '24' is the service number.

Now I know that MTB 24 probably did have the Bofors 40mm as indicated on drawing No 23102 of 17-6-1939. The hull drawings confirm 'as constructed', presumably with the appropriate mountings for the Bofors.

For the benefit of others the boat number 2422 is drawn showing four Thornycroft engines, (two to each prop), but a pencil addition (undated) shows a change in prop shaft line and  a revised prop dia of 27.5 inch to accomodate the Packard engines, (presumably two?).Taken from the hull details, drawn 1938 Drg No 22900

The armament tally for this particular boat comprising of:-

Two 18" torpedo tubes.

Ten depth charges in two roll-off stern racks,

The Bofors 40mm on the aft deck.

Two machine gun positions, one on foredeck and one between the pair of engine hatches and the single engine room hatch aft of the above. The type of machine gun is not given. Again any ideas? I suspect at the vintage of the drawing single 303, but Thornycroft did have well advanced ideas so 50 cal could be possible. (An opinion supported from annother drawing of mid 1939 that shows 21" torpedo tubes when this torpedo did not seemingly enter service till late 1941!)

The machine gun mounts are just a circular flanged socket approximately 4" bore dia,

Thanks again to all, and especialy the coment regards the US Navy who were so prolific in their 'field mods'. I know it took me a year of solid research to sort out what PT109 probably had on board, and what had been 'junked' during JFK's refit.

I hate to knock the Yanks, but PT109 is based on a Thornycroft hull design, all be it built under licence by Elco and others. PT109 is a therefore a British boat.

One final point. The National Maritime Museum, Grenwich, London has an archive section open for private research. The Thornycroft collection is as yet not fully catalogued and tends to be rather chaotic. However the Curator, (Plans and Photos), Andrew Choong is more than helpfull.

Best regards to all and I am open to even more info concerning MTB 24. A photo would be just perfect!

Martin ej

Thornycroft M.T.B. 24  is listed as having 3x issota's when built, the drawings may have been the proposals when the issota's were going to be removed or could be for the Irish boats m.1-6 which were taken off the same hull and probably had variations to the armament and engine set up, it was of course a time when all sorts of "experimental" craft were built from hydrofoils to stepped hulls by various builders including Thornycroft and some vessel's can be difficult to pin down.

I have been informed that John Lambert Plans have produced drawings of MTB 24 & 25 - (See L/S/62)

Also drawings L/S/23 A-B shows a much larger Thornycroft design - MTB's 49- 57 that the Admiralty could use only for Target Towing (G/Box probs) the survivors eventually being sold to Ireland.

Source: JL Plans

Hi All,

Wow! I seemed to have unearthed a mass of further info.

To confirm a few points.

The Thornycroft drawing No 23103 clearly shows detail of the Bofors mountings. This is for boat type 2422.

Thornycroft drawing 22900 is the detail hull dimesions for boats 2422, 2430, 2431, 2471, and 2463/4 It is 71' 9" O/A length. Beam 16'.

Thornycroft drawing No 23303 is clearly marked as for the Irish Govt. and allocated the ID 'M1'. It also states 'As fitted' with the Bofors gun and four Thornycroft RY/12 engines paired to two props. This is dated 25-5-1940. It has four single depth charge racks, port stbd and two on stern. No M/C gun positions, and twin 18" tubes. Further minor differences such as search light location, addition of 10ft life raft, and hydrophone gear on port frd.

None of the drawings make any reference to the Italian engines.

But there are many other drawings in the NMM archives that I did not persue since Boat type 2422 is of particular interest at present.

Regards to all,

Martin ej

MTB28 war loss caught fire while being refuelled and rearmed at HMS Hornet. The crew of MTB102 got a line to her and towed her off the jetty out into Haslar Creek when she blew up. 28 and 102 disappeared in a cloud of mud, water and boat. When it cleared 102 was still out in the creek unharmed.

Strengthened deck heads on Merchant ships. I was always told that the shipping companies got a government grant if these were fitted "just in case". One of my ships, built 1948, certainly had them.

Richard.

2422, is that the Thornycroft yard number? MTB102 was Yard number 1763 which has no relevance to her RN Pennant number.

Richard.

Thanks Ron. Possibly.We have several with the trials flag up. I would need to see to confirm.

Richard.

Hi Tramontana,

Re the fitting of Bofors 40mm. on Thornycroft boats.

Having been in touch with Bofors BAE SYSTEMS Sweeden they have no record as to this application. They may have had but junked their records!

Anyway, from suposition I figure that this application was not practical since laying onto a target was a two man operation, one working traverse, one elevation. That on a rolling MTB would have been near impossible. Probably explains why this boat did not enter acive service.

As for the Irish? Who knows, it's possible. However the drawings for the Irish boats suggest a primary intention for sub hunting being fitted with sonar gear according to the drawings.

regards,

martin ej

Hi Richard,

2422 is the boat type number. Basic hull, internal layout and deck superstructure. I don't think it is a yard number since it covers several boats. Nor is it a service number. Any material changes other than armaments would perhaps have resulted in a different boat type number eg engines since the (faint) pencil note regards Packard engines seems only to be a drawing office comment. Using the 2422 as the start point for another design perhaps?

Regards

martin ej

Hi again Tramontana,

Yes poor old loader withnot much to hang on to!

Post war applications with radar / electronic gun control would probably work well. The 1940 situation, full manual, is rather different. Ever tried a real sail boat in a rough sea? Its no fun handling the sails let alone trying to lay onto a fast moving target.

Regards, martin ej

Hi Tramontana,

Putting on speed to fire over the bows is OK provided the 'hostile' is obliging. Pitty the MTB in question has its Bofors stern mounted so a lot of superstructure and rigging gets in the way! If I was the 'hostile' thats where I would make my run from, come in low and hope to get lucky with the stern fitted fuel tanks.

I never got a chance on the Bofors, appart from a Bren the smallest piece I got familiar with was an 8" howitzer, old style with cordite bags and a 303 blank to fire it. Yes I am quite ancient!

I agree, life jackets are a must in any boat, but sadly my days of messing about in boats are long gone, too much physical abuse and damage to the old bones! So now I build and play with scale models. Hence the interest in the Thornycroft range of MTB's.

Regards,

martin ej

 Hi Martin,

 MTB24 is currently owned by a nice old chap on the isle of wight. She's suffering a bit now but i'm back there next week so i'll try & get some photo's & have a poke in the bilges. He has given me a copy of the plans, if you pm me your address i'll post them on

Hello Jimmy P,

It still exists! Wow!

OK I have all the plans for the 2422 boat(s) class which I think are those for RN service No24. Thanks anyway but I got them from the National Maritime Museum.

Please have a close look at the after deck. If I am correct there should be traces of the two depth charge racks that drop over the stern. Also, just ahead of the access hatch to the aft ammo store there should be evidence of the Bofors gun mounting. This will probably be about two and a half foot square and if below deck, an angle iron framework extending down to the keel, between the four fuel tanks.

A sure fire identification however is the rudder gear. Two of them on external shafts bracketed off the transom. The top of the shafts having the tiller arms that enters the hull through gaitered slots with an internal linkage bar. The bottom of the rudder shaft mountings is also the end bearing for the prop shaft. This is I believe unique to the 2422 type.

Whilst 'rummaging' are its original engines still there? Drawings show four Thornycroft RY 12's. But there is a pencil note making reference to Packard engines, together with a re-drawn prop shaft line, it goes deeper, and notation for 27 and a half inch dia props.

If it is one of the 2422 class another feature is its 'boat shaped' cabin front  its vertical walls having large horizontal slatted air ventilation inlets.

If it is of interest whilst on the IoW the Thornycroft test tank can be seen from Sandown Road on the left at the top of the hill as one goes towards Bembridge from Bembridge Airport. The actual site is known as Steyne Wood Battery. It is a private house now so going in for a look is not realy on. Besides which it is now just a great big green-house, no water! In fact it was the Thornycroft R&D establishment.

I hope you enjoy your visit to the IoW and the weather is kind for you.

Regards,

Martin ej

Hi Martin,

At the Netherlands Institute for Military History (NIMH) I recently found the book: "100 years of Specialized Shipbuilding and Engineering- John I. Thornycroft Centenary 1964" by K.C. Barnaby.

This book has an appendix with yard numbers of most boats/ships built by Thornycroft until 1964.

The following yard numbers are probably helpful for this discussion.

Yard number 2422 - Irish Marine Service M 1

Yard numbers 2430/1 - British MTB 24 & 25

Yard number 2471 - British MTB 28

Yard numbers 2463/4 - Irish Marine Service M 2 and M 3.

According to your drawing numbers, these boats were apparently all based on the same design. However, MTB 24, 25 and 28 had three Isotta Fraschini 1150 hp engines on three shafts, while M 1 to M 3 had four Thornycroft 600 hp RY/12 engines on two shafts.

I read somewhere that M 1 was originally ordered by Estonia. The contract was apparently taken over when war began and the boat was completed for the Irish Marine Service.  

According to my data M 4 to M 6 were of a slightly bigger, slower design than M 1 to M 3.

Data and good photographs of M 1 to M 6 are hard to get by. I would appreciate any data, plan or photograph of these boats.

Regards,

Jan

Hi Martin

I put two photos of MTB 24 as Little Susie here;

http://www.bmpt.org.uk/forum/forum_posts.asp?TID=177&KW=susie&PN=0&TPN=21 - http://www.bmpt.org.uk/forum/forum_posts.asp?TID=177&KW= susie&PN=0&TPN=21

Hi Jan

There is a wealth of footage now available on the Movietone News website   http://www.movietone.com/ - http://www.movietone.com/   , showing Irish MTB M1 (see story No 33219 "Motor Torpedo Boat For Eire" and 39302 "Eire's Defences"). One of the other boats is featured on story No 43215 "Irish Review Of The Year" from 6:17 to 6:45 mins. It is not M1 (she has the distinctive broad flat wheelhouse front). It is one of the other two (M2 or 3) with the broad wheelhouse (but with angled side screens) and clear glass bridge screens as opposed to the RN-style narrow wheelhose with solid bridge mounted wind deflectors (M4-6?).

Regards, Christian.

p.s. I think you'll enjoy these too;

37140 New Torpedo Boat (40K)  
35961 QIII Motor Torpedo Boat    
38484 Hong Kong Defences(Thornycroft MTB 27 and 60ft BPBs) 
                          
40962 Dutch East Indies  
                          
76363 ISRAELI NAVAL MANEOUVRES

Thanks to all the responses, particularly to christian, dgraw and jakw.

The photo of MTB 24 certainly is not the craft of Thornycroft Drg 2422. Nor would it seem then that the drawing numbers corespond to Boat Yard numbers!

Having now almost completed the 1:24th scale model it has revealed a whole host of 'shortcomings' that would explain why it failed to impress the RN! However that does not detract from its place in history, just shows clearly the steep 'learning curve' of the time.

Regards engines and the relevant dates it is improbable that any Issota engines were used after the early part of 1939. Italy and Germany being allies. The Packard engines it seems did not become available until 1940. That leaves just the RY12 engines for the mid to late 1939 build.

Just one last little problem with the model. Just which machine guns were fitted? The two mounting posts do not suggest twined guns. Being equipped with the Bofors suggests that 50 cal may not have been intended since that cal was the recognised AA defence gun. But at the time BSA were touting about with a single 50 cal pan fed gun that would have suited the simple post mounts, its trunion mount point being well back from the muzzle so reducing the ammount of deck space needed for the gunner. This gun failed to gain favour with any of the services due to its meagre magazine capacity, again an indication of the boats design shortcomings?

Regards to all and many thanks for all the responses.

Martin ej

Dear Martin ej,

Regarding Thornycroft yard no 2422. Although this ended up as the Irish Marine Service Public Armed Ship (P.A.S.) M 1, I believe that this boat was originally not intended for Ireland.

In January 1939, Latvia ordered a single MTB from Thornycroft. Ireland ordered her first two MTBs only in May 1939 (probably became M 2 and M 3). When war broke out in September 1939, construction of all MTBs building in British yards for foreign countries was halted. At the same time Ireland wanted to order more MTBs. Probably, the British Royal Navy had no wish to keep a boat driven by four Thornycroft RY/12 engines (they preferred the more powerful Isotta Fraschini engines, which was still available !) and allowed the Irish government to take over the unfinished boat. Simultaneously, three other boats were ordered (to become M 4 to M 6). M 1 was handed over to the Marine Service at Hampton, 18th January 1940 and commissioned as Public Armed Ship on the 29th January, by Lt. Carey. The boat was icebound until 30th January and sailed for home on the 31st January 1940.

This means that the drawings you have may actually represent the Latvian MTB ordered in January 1939, taken over in/after September 1939.

About this boat the Quarterly Journal Warship International 1997, No. 3, provides the following information:

p. 261 cites "Jane's Fighting Ships 1939": "a first MTB was ordered by Estonia from Thornycroft in January 1939. Dimensions: 22 x 4.9 m; 4 engines 1765 kW; over 40 knots; 2-450 mm torpedo tubes"

p.269 cites from the "U.S. Naval Attaché Great Britain Report X Serial No. 333 dated 4 April 1939": "1. The contract for a new type of motor torpedo boat was placed recently with John. I. Thornycroft & Co., Ltd. It will be built at this company's plant at Hampton-on-Thames. This vessel, which is to be built for the Estonian Government, will be 72 ft. long with a beam of 16 ft. There will be four Thornycroft 12-cylinder gasoline marine engines, each of 600 BHP. They will operate two shafts and will be arranged so that the forward engines can be clutched out and cruising can be accomplished on the after engines on each shaft. There will be clutches which can be changed to give the propellors the same number of revolutions as the engines or one-half the number.

3. It is due to complete about June next....".

p. 270 cites from the "US Naval Attaché Report Z serial No. R-256 dated 21 Apr. 1939": "According to German press reports, either two or four motor torpedo boats were ordered early in 1939. "Schiffbau" for 1 April 1939 reported the order for two vessels, about 22 m (72.16 ft.) by 4.9 m (16.07 ft.), powered by four 12-cyl. Thornycroft gasoline engines of 600 HP each. Complement was to be two officers and eight men each."

Unfortunately, there is no information on the guns/MGs carried in addition to the torpedo tubes. Possibly, this armament was to be installed in Latvia. If a 40 mm gun was to be included, the boat had to be strengthened during construction at Thornycroft. This would surely show up in the plans of the boat.

Greetings,

Jan

Hello Jan,

Thanks for all that info. The boat 2422 drawings, June 1939, clearly show the Bofors and the internal angle iron structure for its mounting. Placed between the port and starboard fuel tanks and right down to the keel.

The Thornycroft drawings, I think of a slightly later date but I did not take copies of those, show the configuration for the Irish Navy, M1 to M6, a configuration clearly for sub hunting equipped with sonar.

So it would seem that this boat did not fall into the hands of the RN though I would guess that to be unlikely if it actualy got built to drawing. It would after all have been a worthwhile craft if only for evaluation trials.

The info on the transmission system was most usefull, but like most of the craft it shows up the lack of experience, both 'combat experience' and mechanical. Coupling two engines is not simple, the cyclinder firing must be maintained 'in phase' otherwise torsional vibration problems arrise leading to mechanical failure. Simple clutches dont work. Even load matching the throttles is a major problem. I must admit I was puzled by the size of the gearboxes, far too big for simple forward / reverse boxes, the two speed feature explains it!

Thanks again for adding to the background history.

Now that I have finished the model I will be progressing on to the next one in Thornycrofts list of MTB designs.

Hopefully one day to have a complete set of all their WW II MTB's.