Dutch Destroyers

[Borys]

Ahoj!
The 10 rpm burst ROF of the 4,7 guns is attainable in calm seas. NOI and Great Rift - possible. Not in the North Sea.

In a way it funny that the Habsburgs are designing their ships with the most awful weather in mind :)

And when talking about 4,7/5 inch guns - the USN found the 5"/51  guns to be too heavy and cumbersome on their c.1000 ton flush deckers. IMO a viable 5 inch gun for such small boats - without penalty of slow train, etc. - should be 35-40 calibre lenght.

As to the French 5,5" guns - maybe someday someone will have a stroke of genious and introduce separate ammo for these guns ....

Borys

[Korpen]

Ahoj!
The 10 rpm burst ROF of the 4,7 guns is attainable in calm seas. NOI and Great Rift - possible. Not in the North Sea.

In a way it funny that the Habsburgs are designing their ships with the most awful weather in mind :)

And when talking about 4,7/5 inch guns - the USN found the 5"/51  guns to be too heavy and cumbersome on their c.1000 ton flush deckers. IMO a viable 5 inch gun for such small boats - without penalty of slow train, etc. - should be 35-40 calibre lenght.

As to the French 5,5" guns - maybe someday someone will have a stroke of genious and introduce separate ammo for these guns ....

Borys

Dutch ships are designed with the worst possible weather in mind, something already stated, but the Netherlands do not expect the smallest combat crafts to be able to perform much action in storms and high seas, so priority is put in the ability to survive the worst weather.

I think it is important not to stare bliondly at the seaboat rating, as it is a relative, not absolute messurment.

Considering that the Us 5"/51 was a extremely powerful gun, it does not surprise me that it could give problems to some ships.

I think it is important not to stare blindly at the seaboat rating, as it is a relative, not absolute measurement. The seaboat rating is how well the ships perform in sea at top speed relative other ships of the same size.

[Korpen]

Finalized version, using a slightly less powerfull 12cm gun.
Still enogh misc weight for a radio, four torpedoes and two paravanes.

G-Class, Netherlands Jager laid down 1908 (Engine 1909)

Displacement:
   750 t light; 786 t standard; 915 t normal; 1 018 t full load

Dimensions: Length overall / water x beam x draught
   290,72 ft / 280,51 ft x 28,05 ft x 9,78 ft (normal load)
   88,61 m / 85,50 m x 8,55 m  x 2,98 m

Armament:
      5 - 4,72" / 120 mm guns in single mounts, 46,30lbs / 21,00kg shells, 1908 Model
     Breech loading guns in deck mounts
     on centreline ends, majority aft, 3 raised mounts - superfiring
      4 - 0,59" / 15,0 mm guns in single mounts, 0,10lbs / 0,05kg shells, 1908 Model
     Machine guns in deck mounts
     on side, all amidships, all raised mounts - superfiring
   Weight of broadside 232 lbs / 105 kg
   Shells per gun, main battery: 140
   4 - 17,7" / 450 mm above water torpedoes

Armour:
   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   0,39" / 10 mm         -               -

Machinery:
   Oil fired boilers, steam turbines,
   Direct drive, 2 shafts, 17 226 shp / 12 851 Kw = 29,00 kts
   Range 4 000nm at 12,00 kts
   Bunker at max displacement = 232 tons

Complement:
   83 - 108

Cost:
   £0,116 million / $0,462 million

Distribution of weights at normal displacement:
   Armament: 33 tons, 3,6 %
   Armour: 5 tons, 0,6 %
      - Belts: 0 tons, 0,0 %
      - Torpedo bulkhead: 0 tons, 0,0 %
      - Armament: 5 tons, 0,6 %
      - Armour Deck: 0 tons, 0,0 %
      - Conning Tower: 0 tons, 0,0 %
   Machinery: 440 tons, 48,1 %
   Hull, fittings & equipment: 254 tons, 27,7 %
   Fuel, ammunition & stores: 165 tons, 18,1 %
   Miscellaneous weights: 18 tons, 2,0 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     239 lbs / 108 Kg = 4,5 x 4,7 " / 120 mm shells or 0,2 torpedoes
   Stability (Unstable if below 1.00): 1,39
   Metacentric height 1,3 ft / 0,4 m
   Roll period: 10,3 seconds
   Steadiness   - As gun platform (Average = 50 %): 70 %
         - Recoil effect (Restricted arc if above 1.00): 0,37
   Seaboat quality  (Average = 1.00): 1,06

Hull form characteristics:
   Hull has rise forward of midbreak
   Block coefficient: 0,416
   Length to Beam Ratio: 10,00 : 1
   'Natural speed' for length: 16,75 kts
   Power going to wave formation at top speed: 66 %
   Trim (Max stability = 0, Max steadiness = 100): 66
   Bow angle (Positive = bow angles forward): 20,00 degrees
   Stern overhang: 3,28 ft / 1,00 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      19,03 ft / 5,80 m
      - Forecastle (15 %):   17,06 ft / 5,20 m
      - Mid (32 %):      17,06 ft / 5,20 m (9,19 ft / 2,80 m aft of break)
      - Quarterdeck (10 %):   9,19 ft / 2,80 m
      - Stern:      9,19 ft / 2,80 m
      - Average freeboard:   11,82 ft / 3,60 m

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 184,3 %
      - Above water (accommodation/working, high = better): 92,5 %
   Waterplane Area: 4 893 Square feet or 455 Square metres
   Displacement factor (Displacement / loading): 49 %
   Structure weight / hull surface area: 27 lbs/sq ft or 131 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0,50
      - Longitudinal: 1,78
      - Overall: 0,56
   Hull space for machinery, storage, compartmentation is cramped
   Room for accommodation and workspaces is adequate
   Ship has slow, easy roll, a good, steady gun platform

[Borys]

Ahoj!
Actually, going by the picture, four guns are "elevated". Forecastel, forecastle elevated, amidships elevated, aft elevated. But it probably makes no difference. The gain in speed is beneficial.
Borys

[Korpen]

Ahoj!
Actually, going by the picture, four guns are "elevated". Forecastel, forecastle elevated, amidships elevated, aft elevated. But it probably makes no difference. The gain in speed is beneficial.
Borys

There are no guns mounted on what springsharp considers the forecastle, it just that the hull midbreak is quite far forward, the forward guns are mounted on the 18% of the hull that is the mid forward of midbreak.

[Korpen]

Ahoj!
The 10 rpm burst ROF of the 4,7 guns is attainable in calm seas. NOI and Great Rift - possible. Not in the North Sea.

In a way it funny that the Habsburgs are designing their ships with the most awful weather in mind :)

And when talking about 4,7/5 inch guns - the USN found the 5"/51  guns to be too heavy and cumbersome on their c.1000 ton flush deckers. IMO a viable 5 inch gun for such small boats - without penalty of slow train, etc. - should be 35-40 calibre lenght.

As to the French 5,5" guns - maybe someday someone will have a stroke of genious and introduce separate ammo for these guns ....

Borys

Actually, as the L/45 (21kg shell) gun use fixed ammunition, 10rpm is never really out of the question, if the historic guns with fixed ammunition if anything to go by (8-12 RPM seems like the average).
And while about 34kg  (21 complete round) is heavy to load, it is not really an inhuman load to handle quickly and repeatedly. As surface fire is at much lower elevation some of the problems of rapid fatigue is much reduced compared to the need of AA fire were it has to be rammed upwards.
Of course if conditions are really bad the ROF could drop far lower then that, but in those cases the gun crew on lighter guns will have just as much problems. :)
The real drop off in ROF will happen when the ready ammunition is used up, but that is a problem shared with all ships with deck guns.

Did some more research on the problems with 127mm guns on US destroyers. Most of those problems seem to be that the ships were rearmed with the guns later in their life. Their original armaments were 10cm guns, and getting trouble when mounting guns significantly more powerful then the ships were designed for is no surprise.

[Korpen]

Well, inspired by Carthaginians drawing of the CSA ship, I have given a shot on making a larger scale drawing of the G-Class.
Scale is 1pixel=1dm
The drawing needs some more work, such as adding details to the deck.

[Borys]

The skellies are cute.

[Korpen]

The skellies are cute.

My, thank you.
They are included for size comparison, they are about as large as an avarage dutch seaman.

[Carthaginian]

Excellent drawing... and made me realize that my gun mounts need some work. :)
Keep it up!

[Korpen]

Well looking to convert some old TBs for use in other roles, mainly mine laying and sweeping.
The first ideas include ripping out the old engines, and mount a more modern engine packet, but only in half the old space. The freed space being used for more fuel. An extra 5cm gun is getting mounted on the forecastle, and a radio is getting fitted. The remaining of the extra misc weight is to be used to mount mine warfare equipment, as well some extra crew space.
The cost would be about 0,15bp and €0,24 per boat.

Any thoughts?

Orginal ship: http://www.navalism.org/index.php?topic=690.msg4399#msg4399

C-Class (M), Netherlands Enter ship type laid down 1895 (Engine 1909)

Displacement:
   344 t light; 355 t standard; 471 t normal; 564 t full load

Dimensions: Length overall / water x beam x draught
   180,45 ft / 180,45 ft x 20,01 ft x 10,01 ft (normal load)
   55,00 m / 55,00 m x 6,10 m  x 3,05 m

Armament:
      3 - 1,97" / 50,0 mm guns in single mounts, 3,81lbs / 1,73kg shells, 1905 Model
     Quick firing guns in deck mounts
     on centreline ends, majority aft, all raised mounts - superfiring
      2 - 0,31" / 8,0 mm guns in single mounts, 0,02lbs / 0,01kg shells, 1895 Model
     Machine guns in deck mounts
     on side, all amidships, all raised mounts - superfiring
   Weight of broadside 11 lbs / 5 kg
   Shells per gun, main battery: 150

Armour:

   - Conning tower: 0,98" / 25 mm

Machinery:
   Oil fired boilers, complex reciprocating steam engines,
   Direct drive, 2 shafts, 1 972 ihp / 1 471 Kw = 17,85 kts
   Range 5 420nm at 12,00 kts
   Bunker at max displacement = 209 tons

Complement:
   49 - 65

Cost:
   £0,033 million / $0,130 million

Distribution of weights at normal displacement:
   Armament: 1 tons, 0,3 %
   Armour: 1 tons, 0,3 %
      - Belts: 0 tons, 0,0 %
      - Torpedo bulkhead: 0 tons, 0,0 %
      - Armament: 0 tons, 0,0 %
      - Armour Deck: 0 tons, 0,0 %
      - Conning Tower: 1 tons, 0,3 %
   Machinery: 138 tons, 29,3 %
   Hull, fittings & equipment: 166 tons, 35,2 %
   Fuel, ammunition & stores: 127 tons, 26,9 %
   Miscellaneous weights: 38 tons, 8,1 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     469 lbs / 213 Kg = 123,1 x 2,0 " / 50 mm shells or 0,4 torpedoes
   Stability (Unstable if below 1.00): 1,10
   Metacentric height 0,5 ft / 0,2 m
   Roll period: 11,4 seconds
   Steadiness   - As gun platform (Average = 50 %): 100 %
         - Recoil effect (Restricted arc if above 1.00): 0,08
   Seaboat quality  (Average = 1.00): 2,00

Hull form characteristics:
   Hull has raised forecastle
   Block coefficient: 0,456
   Length to Beam Ratio: 9,02 : 1
   'Natural speed' for length: 13,43 kts
   Power going to wave formation at top speed: 55 %
   Trim (Max stability = 0, Max steadiness = 100): 50
   Bow angle (Positive = bow angles forward): 0,00 degrees
   Stern overhang: 0,00 ft / 0,00 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      16,40 ft / 5,00 m
      - Forecastle (25 %):   16,40 ft / 5,00 m (8,20 ft / 2,50 m aft of break)
      - Mid (50 %):      8,20 ft / 2,50 m
      - Quarterdeck (15 %):   8,20 ft / 2,50 m
      - Stern:      8,20 ft / 2,50 m
      - Average freeboard:   10,25 ft / 3,13 m

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 106,5 %
      - Above water (accommodation/working, high = better): 73,8 %
   Waterplane Area: 2 315 Square feet or 215 Square metres
   Displacement factor (Displacement / loading): 144 %
   Structure weight / hull surface area: 29 lbs/sq ft or 142 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0,82
      - Longitudinal: 5,78
      - Overall: 1,00
   Hull space for machinery, storage, compartmentation is adequate
   Room for accommodation and workspaces is cramped
   Ship has slow, easy roll, a good, steady gun platform
   Excellent seaboat, comfortable, can fire her guns in the heaviest weather

[The Rock Doctor]

I don't know if the additional range is really necessary - they'll be too slow to work as offensive layers, and won't be travelling too far as defensive sweepers.

The idea's not a bad one.  Would a torpedo-boat have a long shelf-life after spending ~13-14 years in service with a hull strength of 0.50?  It might be getting somewhat beaten up.

[Korpen]

I don't know if the additional range is really necessary - they'll be too slow to work as offensive layers, and won't be travelling too far as defensive sweepers.

The idea's not a bad one.  Would a torpedo-boat have a long shelf-life after spending ~13-14 years in service with a hull strength of 0.50?  It might be getting somewhat beaten up.

The longer range is to make it possible for them to operate together with the main fleet units, and fulfil the role of long range sweepers to some degree.

As for wear, it is true that some of the ships might be in a worn state, but just a bit over ten years in the water, mostly in peace (very few of these boats see much service in the last war), it seems unlikely that they will have reached the end of their hull life. At least not in the less strenuous work they would get as mine warfare ships. That is at least what is hoped for.
The largest worry is that refitting them will be more expensive then building a new AM-class sweeper. The advantage they would have over those ships is that they are larger, better range and better sea boats, so more suited to support fleet units.

[P3D]

How did you arrive at the $0.24 price? The engine is $0.28, the refit itself is $0.1. You can almost build a 300t minesweeper from scratch for the price.

I'd rip out half the boilers (I'll check some numbers but my first guess is 100-150t for the boilers), install oil burners in the coal boilers, and you'd have 50-75t for more fuel and misc. weight.

[Korpen]

How did you arrive at the $0.24 price? The engine is $0.28, the refit itself is $0.1. You can almost build a 300t minesweeper from scratch for the price.

I'd rip out half the boilers (I'll check some numbers but my first guess is 100-150t for the boilers), install oil burners in the coal boilers, and you'd have 50-75t for more fuel and misc. weight.

The new engines are not 280 tons, but 138ton, so 0,14 and then 0,1 for the refit itself.
I think boilers are included in the machinery weight, as the weight of the machinery changes when one changes boilers. In any case if the boilers were 150 tons, the engine+boilers would weight more then the entire ship at normal displacement.
Adding the cost of fuel would be strange, as that is never included in the cost of the ship otherwise, and most of the misc weight is potential cargo (mines).

EDIT:
On second reading, did you mean to keep the engines and just rip the boiler out, and that the quoted weight for boilers were only a  proportion of the engine?
A problem witht hat is that SS do not allow oil fuel at that engine date.