NZ navy 72ft wooden HDMLs reclassified as SDMLs for fishery protection work had either Foden6 or Foden12 as main engines. The 12s were a bit of a pain. Loved the cackle of the exhaust on those screaming 6s

 

Fd12

12th ed. of The Modern Diesel has a photo of an FD12 (attached), and states they were effectively a pair of 6-cyl. engines side-by-side with their cranks geared together in a common crankcase. Cont. rating of 210bhp @ 1800rpm.
At that time (1954), it states the FD12 was the "latest" development in the range.
6th ed. of The British Diesel engine Catalogue lists a Mk. VI & VII of the FD12, each with H.Ex. or Radiator cooling for generator application, as well as the same Mk's for marine application.

Respective outputs were:
Generator, Mk. VI, H.Ex. 214bhp @1500 / 252bhp @ 1800 (143/168 Elec. kW)
Generator, Mk. VI, Rad. 208bhp @1500 / 243bhp @ 1800 (139/162 Elec. kW)
Generator, Mk. VII, H.Ex. 300bhp @1500 / 375bhp @ 1800 (200/250 Elec. kW)
Generator, Mk. VII, Rad. 294bhp @1500 / 336bhp @ 1800 (196/244 Elec. kW)
Marine, Mk. VI, 252bhp @ 1800, 309bhp @ 2000
Marine, Mk. VII, 375bhp @ 1800, 440bhp @ 2000

The big difference in outputs from Mk. Vi to VII is explained by the Mk. VII being listed as turbocharged, in addition to the scavenge blower.
Bore and stroke are common to all the FD range. Weights are listed for all, but I will just give marine Mk. VII dimensions of 1847kg, 2.334m x 1.15m x 1.508m (LxWxH).

Hope that is some assistance.

Brianwnz,
Swan Hill,
VIC, Australia

 

spent some time on the Brecon - she was one of 4 fitted with the FD12. Two FD6 engines were driving a common crankshaft.

Foden built the FD12 and went bust supporting it. Rolls-Royce Engines (the same that made the motor car in Coventry) were asked to take over support. I went to the RR factory to investigate Cylinder Head issues when the 4 minesweepers were sent to the Gulf of Oman. Turned out to be a problem with higher ambient temperatures.

 

Fd12

Thanks all for the great response!
Rosels: My guess is they were a pain because of no access between the two rows of cylinders. And it was probably needed, every so often.
Brian: Couldn't have hoped for more! Much appreciate the time and trouble to put together that info.
Steve: Knowing something of the FD6, no surprise the FD12 was twice as difficult, or maybe even more so. I had heard that RR had taken over what was left of Foden, but when I contacted the company they claimed to have no knowledge. Probably it was too long ago, the guy who replied must have been too young to have even heard of Foden.

 

I was doing my six months spell in the Dockyard drawing office during my last year having come from a similar stint in the Internal Combustion Engine shop that serviced the fleet's motor boats where they were completing several up date refits on the 72 foot HDML fishery protection launches .
The updates involved refits to those with Grey Marine diesels and replacing some with Grey engines in lieu of the Hercules engines used during wartime .
Although the Dockyard was owned by the NZ Defence Department it had been beholden to the wishes of the British Admiralty in regard to standardisation and equipment installation hence the huge gun barrel lathe designed to service 16 inch gun barrels of battle ships installed in the pre war years and other equipment such as Gleason Gear Hobbing machines and other sophisticated machines , some of them commissioned then put under dust covers until the hour of need .
When the drawing office received a notice from U.K. Admiralty that they were standardising on the Foden engines and that we should consider doing likewise the reaction from the Dockyard engineers was negative, no way were they going to change yet again.
I left to go to sea soon after and never knew the outcome but Rosel's
Post 2 tells the story .

Bob

 

Only saw an FD12 once - in one of our 'Fish Boat' squadron vessels.
The FD6 Mk I had one cylinder head covering each grouping of 3 cylinders.
The FD6 Mk VI had one little cylinder head per cylinder.
But can't remember if the Mk XII had 4 heads or 12 heads per engine, or even 2 x 6-cylinder heads.
Evidently they had exhaust gasket problems as the 12 exhausts all exited the heads on the top middle of the engine thus a lot of heat was generated in this area.
I never could reason why some NZ HDMLs had the FD12s as they swung the same diameter & pitch props as the FD6s, and ran the same revs. But for double the consumption?? Why?
I did have a good photo somewhere but haven't been able to find it.
Skilly

 

FD 6 engines powered the Whenuapai Bus company's new bus fleet during the 60's , when the engines were called 'screaming skulls' . Nice buses though .

Bob

 

And why were they called the 'Screaming Skulls'?

Just listen (& watch) to this!

 

I collect engines and am now a proud owner of a FD12 Mark VII. picture bellow and a link to what it sounds like running (chap running is the guy I bout it off).

hope you enjoy it, people do as its by far my most popular video!

Rob