You are not logged in.

Dear visitor, welcome to WesWorld. If this is your first visit here, please read the Help. It explains in detail how this page works. To use all features of this page, you should consider registering. Please use the registration form, to register here or read more information about the registration process. If you are already registered, please login here.


Tuesday, July 18th 2006, 12:27pm

Chinese Patrol boats



Dagu - Class

Displacement: 65 t
Length: 27,73 m
Wide 7,16 m
Draught 1,05 m
Engine 2 Huang Po Diesel-Engines M 50 F3
Power 3.530 KW
Speed: 34,3 kn

1x4 25 mm Machinegun
1x2 12,7 mm Machinegun

Seems a wee bit ahead of the current designs from other country's. Is this a historical design?


Tuesday, July 18th 2006, 12:30pm

Seems to be soviet on account of the duple 57mm gun aft.




Tuesday, July 18th 2006, 1:40pm

You are right Wes, it is no historical Design, but it is also no Russian Design.
May be a little bit to modern at present. Even if equivalent it has a little similarity with an American PT-boat. But those are also only built after 1940. If the draft should have to be to modern in your eyes, then it will remain a draft and into service will not step.


Tuesday, July 18th 2006, 9:13pm

Acctually I'm more curious as to the engine outfit as thats where the real gem of these designs is at.


Engine 2 Huang Po Diesel-Engines M 50 F3
Power 3.530 KW
Speed: 34,3 kn

I'm afraid I'm not familiar with the convertion table for KW to HP. Is it a total KW of 3,530 or per engine?


Tuesday, July 18th 2006, 9:20pm

My Magic Calculator tells me:
1 HP = 0.7457 kW
1 kW = 1.341 HP

... so that would be 4733.73 HP.
And I would assume that that is the combined output of the two engines.


Tuesday, July 18th 2006, 9:23pm

I knew that I recognised the drawing style from somewhere.

3530kW is 4700hp combined, so 2350hp engines, which don't exist.

I'd expect China to have help from a country that already operates such types; Atlantis, Great Britain, Germany, Italy...


Wednesday, July 19th 2006, 5:24am

Thats quite abit of power for 2 engines, even diesels. A 1957 design wouldn't likely be the best choice of designs to copy for 1931/2. The most modern Atlantean designs use three 1,200 hp Roth-Packard liquid cooled engines to reach 41 knots.

Thats a total of 3,600 hp and its effectively on the edge of realism considering 1000 hp engines are starting to make their way into aircraft now.

If you split the hp between 4 engines it would seem more realistic. Likely four 900/1000 hp engines would be utilized.

The list of country's already building these types of boats makes it super easy for China to aquire some outside designs or assistance in designing one.




Wednesday, July 19th 2006, 7:50am

Then I would suggest that it is only one Style study. Will thus accordingly proceed and this ship type will completely revise. Hope it is okay.




Wednesday, July 19th 2006, 4:19pm

The data will be nearly the same


Dagu - Class

Displacement: ~ 60 t
Length: < 30 m
Wide: ~ 7 m
Draught: ~1 m better < 1m
Engine: 2 Huang Po Diesel-Engines M 50 F3
Speed: ~ 34,3 kn

2x2 25 mm Machinegun
1x2 12,7 mm Machinegun
DC thrower or DC rail

Maybe someone can paint the ship for me, because i'm very busy at present


Wednesday, July 19th 2006, 6:02pm

Its the engines that are the problem. Those Packard engines don't exist yet. We're limited to about 20hp/litre at the moment so 1200hp requires 60litre engine instead of the 41litre Packard V12. Sure a larger engine could be built, but it will weigh considerably more, which means less weight for torpedoes and guns. Nothing against introducing alternate engines, but more powerful ones will be heavier. In the case above with the Packard, its neccessary to ditch the torpedoes because of the excess engine weight. Or maybe just reduce the gun armament to 2-3 mgs.


Wednesday, July 19th 2006, 9:19pm

The initial batch of boats are armed with 18" torpedo's so yeah they have ditched weight for the motor's. They are about 5 years ahead of their time, but certainly not 20 years.




Thursday, July 20th 2006, 7:51am

The Dagu-Class haven't any torpedos, so we have here no possibility to ditch some weight. And i think the armament is the minimum such a boat should have. So i think we have two options. First we could increase the displacement or we reduce the speed so we could fit the packard motor inside.
Because as you said, the machines are probably the problem. I do not know myself with the engines at that time, but perhaps you could say to me which engines and/or which speed the boat with existing machines can reach .


Thursday, July 20th 2006, 8:30am

The Dagu class could likely use 3x1000 HP motors to achieve the same specified speed of 34.3 knots.

Here are some various engines and their BHP/weight

Napier Sea Lion - 500- 1652lb
Isotta-Fraschini -1100- 2699lb
Rolls-Royce merlin-1100- 2240lb
Packard 4M-2500 -1500- 3017lb

IIRC these are 1939 figures so I'm guessing that a 1000HP motor in 1932 would weigh about the same as the 1939 Packard engine (3000 lb's).

Using three 1000 HP engines would give you about 4.5 tons of weight devoted to engines.

The twin 50 cal would weigh about 1200-1500 lb's depending on the number of rounds carried (1300 to ?).

The two twin 25mm mounts would likely be 3,000 lb's per twin mount depending on the number of rounds carried. A powered mounting would likely weigh more, maybe 2 tons?

That would be a total of 7.25 tons for main armament and engines.

How many DC would the Dagu carry?




Thursday, July 20th 2006, 12:27pm

That's a good question. I think it should carry round about 10 DC's. Maybe 6 or 8 are enough, i don't know. It's not the task to find and destroy a sub, so we needn't much DC's.


Thursday, July 20th 2006, 11:12pm

I'd think 6 DC's would seem reasonable for a patrol boat, basically hit and run to temperarily deter a sub.




Friday, July 21st 2006, 12:42pm

Let us say, she will have 6 DC plus a DC-rail. So what do you think it's now the weight of the Dagu-Class and how does she look like ?


Friday, July 21st 2006, 12:57pm

Going with 60 tons , 2x2 25 mm Machinegun,1x2 12,7 mm Machinegun, 6xDC thrower and DC rail I'd say shes similar in size to the Atlantean motor launchs.


Friday, July 21st 2006, 1:10pm

Its reasonable compared to Stefano Turr. Similar size, power and speed. Just trading torpedoes for 25mm guns. Having torpedoes gives more options, more likely for China to encounter larger ships than to be fighting MTBs. The Fiat diesels used were unreliable and underpowered compared to the petrol engines used in other MAS. Also, only 1000 more hp for a boat 3 times larger so speed suffered.

Mas Stefano Turr


Displacement 58t standard, 61.6t normal, 68.5t full load
Dimensions 32.0m x 5.95m x 1.32m (just 0.95m according to Conway's)
Engines 4x Fiat V1616 Diesels, 4x 750hp
Speed 34kts project, 30-32kts real
Range 750nm/25kts - 1,582nm/16.6kts
Fuel 10t normal, 16t full load
Crew 16
Armament 4x 450mm torpedoes, 2-3x 13.2mm MG, 1x 6.5mm MG, 12x ASW bombs




Friday, July 21st 2006, 1:33pm

The Dagu-Class needn't torpedos, because i have the Shanghai-Class as a torpedo-carrier.

So we have now following Datas:

Displacement: 60t normal
Length: 30m
Wide: 7.15m
Draught: 1.12m
Engines: 3000hp (3x1000hp)
Speed: 34.3kts
Crew: 14

2x2 25mm MG
1x2 12.7mm MG
6x DC's

So we need only a drawing of the ship.


Friday, July 21st 2006, 1:38pm

Seems reasonable.

You could likely add another twin 12.7mm mount to give you one 25mm mount forward, one aft and two twin 12.7mm mounts on either side of the wheelhouse.