Dark Aggressor firing off all four torpedoes


Saunders Roe produced six "Dark" Class (Admiralty type A) Fast Patrol Boats together with other British boat builders like Vosper.

Many of the ones illustrated are again from the newly discovered collection together with MTB 539 (P1602)

The company also build two similar craft for Finland, five for Burma and one for Japan. The Burmese being again all-aluminium alloy hulled.

As far as I'm aware they were all fitted with Napier Deltic 18 cylinder two-stroke engines. 

P1120 Dark Scout was the last built and had an all welded aluminium alloy hull. The bridge was also of a simpler design without the 'flaired' side spray deflectors. She was the only SARO built Dark with stern exhausts from twin Napier Deltic Diesel two-stroke engines. All other Dark Class had side exhausts.

Dark Adventurer, Aggressor, and Biter in January 1957


 List of constructed Admiralty type "A" craft for the Royal Navy

showing contractor and launch dates - (courtesy Ted Else)

Dark Adventurer


Saunders-Roe (Beaumaris)

October 28th 1954

Dark Aggressor


Saunders-Roe (Beaumaris)

December 9th 1954

Dark Antagonist


Saunders-Roe (Beaumaris)

February 11th 1955

Dark Biter


Saunders-Roe (Beaumaris)

June 23rd 1955

Dark Avenger


Saunders-Roe (Beaumaris)

September 6th 1955

Dark Buccaneer


Vosper (Porchester)

September-30th 1954

Dark Clipper


Vosper (Porchester)

February 9th 1955

Dark Highwayman


Vosper (Porchester)

March 29th 1955

Dark Fighter


Taylor (Chertsey)

October 4th 1955

Dark Gladiator


Taylor (Chertsey)

December 5th 1956

Dark Hero


McGruer (Clynder)

March 16th 1957

Dark Hunter


Miller (St. Monance)

March 18th 1954

Dark Hussar


Thornycroft (Hampton)

May 16th 1957

Dark Intruder


Morgan Giles (Teignmouth)

July 6th 1955

Dark Invader


Morgan Giles (Teignmouth)

September 5th 1955

Dark Killer


Thornycroft (Hampton)

September-26th 1956

Dark Rover


Vosper (Porchester)

August 30th 1954

Dark Scout


Saunders-Roe (Beaumaris)

March 28th 1958

Cancelled Craft
No Pennant Numbers issued - (Courtesy Ted Else)

Dark Attacker



Dark Battler



Dark Bowman



Dark Chaser



Dark Chieftain



Dark Crusader



Dark Horseman


Part built

Dark Defender



Dark Explorer





Wikipedia Error:

My corrections in yellow. Wikipedia states:

"The boats were made of alloy framing with wooden ALUMINIUM decks and WOODEN skin. The exception was Dark Scout which had all WELDED aluminium decks, skins and frames. Originally 27 units were ordered by the admiralty from seven builders. Nine were eventually cancelled in 1955, including Dark Horseman which at the time was partially completed and on the stocks in the builders yard".

The all-aluminium version was exported to Burma (five units), Finland (two units), and Japan (one unit) by builders Saunders-Roe. Only the five Burmese were riveted aluminium while FINLAND and JAPAN had timber on aluminium framed hulls.


Dark Adventurer P1101

P1101 Dark Adventurer launching October 1954.

A rare colour photograph of P1101 Dark Adventurer looking a bit worse for wear. Could it be this one that ran into Beaumaris Pier?


P1101 Dark Adventurer. 


Christening entourage. SARO photographer "Geordie" Edington in the foreground with my favourite MPP Mk4 5"x4" camera that I used when I was an apprentice.


 P1120 Dark Scout launching

P1120 Dark Scout launching 

 P1120 Dark Scout


P1120 Dark Scout in black showing its unique stern exhausts from twin Napier Deltic Diesel two-stroke engines. All other Dark Class had side exhausts. Dark Scout was the last built for the Royal Navy Coastal Forces and had an all welded aluminium alloy hull. The bridge was also of a simpler design without the 'flaired' side spray deflectors.


Some fine animations of the two-stroke Napier Deltic Diesel engine. This clever design has the opposing pistons fracionally out of phase to allow the inlet ports (green) to open slightly ahead of the exhaust ports (purple). This allows the gas flow to scavange the cylinder more effectively. The inlet was 'blown' into the cylinders unlike conventional 2-stroke designs. The three crankshafts were all geared together with the final drive from the lower shaft.



These engines had a distintive sound and were also rather smoky in operation. The "Light Admiralty Grey" paintwork soon became badly discoloured with the oily exhaust fumes so the hulls were repainter black. Initially an experimental paint scheme was tested with the rear half of the hull black and the front left grey (see 1/24 scale model below of Dark Biter P1104), but it was finally decided to use overall black paintwork.




 NAUTICAL MARINE 1/24 scale DARK BITER P1104 (half black hull)


Other MTB/MGB's 



Like the experimental  MTB 539, all five Burmese FPB's (T201-T205) had all-aluminium riveted hulls to withstand marine worm attack.

My father told me that the Burmese Government paid for them with rice.

First Burma MGB (Motor Gun Boat) T201 with Dark Avenger P1105 in the background.

The Port side exhaust outlet is obscured from view by the man on the ladder. The slipway crossed the main road to SE Anglesey and Penmon at this point. It was here that the launchings took place and the public could get an excellent view of the boats.


T201 clarly showing the dirty exhaust problems with a light grey hull. I looks like the outlet was just behind the rear vertical lauching trolley support.


Two Burmese Patrol Boats at Menai Bridge pier.

Trials off Penmon


Trials off Anglesey. Photo appears to have taken from the bridge. 


David Mills on gun duty.

David Mills at the helm. The boat was on the old slipway that was used for flying boats during WW2. The light patch behind the trees was the 'compass base' where the flying boats were swung round to calibrate their compasses. This was my second time behind the wheel of a Saunders Roe boat as I also got a trip along the Menai Striat to Port Dinorwic on one. I would love to re-enact this scene on MTB 539.


Two were built named VASAMA 1 and VASAMA 2. 

They were of conventional timber on aluminium frame construction with the same riveted aluminium decks as the RN Dark Class.

Vasama's 1 and 2 at speed. The side exhaust being clearly visible.


Vasama 1 and Vasama 2 naming ceremony at Menai Bridge pier. 8 May 1956 


Saunders-Roe staff and families taking the Finnish delegation on a sight-seeing trip around North Wales. Tal Y Cafn bridge over the River Conway in the background.

(David Mills sitting on the grass (right of the three boys)



This was the last FPB built at Saunders-Roe and was of standard timber construction the same as the Finnish and Royal Navy boats.

PT9 appears to be running west along the Menai Strait with what could be the hills around Bangor just visible.


Little is known at present about PT9. She appears to have been simillar to the Dark Class as the torpedo tube racks appear to be present. She probably had a similar riveted aluminium hull to the Burmese boats. 

She arrived at Yokosuka Naval Base on 29th July 1957, accepted into the Japanese Naval Defence Force on the 2nd September 1957 and given the Pennant Number of PT9, finally being ‘struck off’ in 1972.



Could this be the only surviving Dark Class built by Saunders-Roe ? 

Her aluminium hull is thought to be that of P1116 Dark Scout although it is thought here are some dimensional discrepancies between them!

It is presently unknown if she has an all welded hull like Dark Scout.

Photographed at Port Canaveral, Florida and named 'SCUBA DOO'.

If she is not Dark Scout it would mean that MTB 539 is the only SARO survivor



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