Strange effects of re-engining ...

[Borys]

Ahoj!
Here is the original. The date is 1885, but that's the date of the design - she was buil around 1900 ....
graz, austro-hungary (hapsburg empire) torpedo boat/destroyer laid down 1885

Displacement:
4,493 t light; 4,610 t standard; 4,912 t normal; 5,154 t full load

Dimensions: Length overall / water x beam x draught
310.70 ft / 300.00 ft x 50.00 ft x 22.00 ft (normal load)
94.70 m / 91.44 m x 15.24 m x 6.71 m

Armament:
4 - 4.00" / 102 mm guns (2x2 guns), 29.60lbs / 13.43kg shells, 1885 Model
Quick firing guns in deck mounts
on centreline ends, evenly spread
6 - 3.00" / 76.2 mm guns in single mounts, 12.49lbs / 5.67kg shells, 1885 Model
Quick firing guns in deck mounts
on side, all amidships
6 - 1.10" / 27.9 mm guns in single mounts, 0.62lbs / 0.28kg shells, 1885 Model
Quick firing guns in deck mounts
on side, evenly spread
Weight of broadside 197 lbs / 89 kg
Shells per gun, main battery: 150
6 - 14.0" / 355.6 mm above water torpedoes

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 2.00" / 51 mm 250.00 ft / 76.20 m 10.00 ft / 3.05 m
Ends: 2.00" / 51 mm 50.00 ft / 15.24 m 10.00 ft / 3.05 m
Upper: 2.00" / 51 mm 250.00 ft / 76.20 m 5.00 ft / 1.52 m
Main Belt covers 128 % of normal length
Main belt does not fully cover magazines and engineering spaces

- Torpedo Bulkhead:
1.00" / 25 mm 250.00 ft / 76.20 m 20.00 ft / 6.10 m

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 3.00" / 76 mm 2.00" / 51 mm -
2nd: 2.00" / 51 mm - -
3rd: 1.00" / 25 mm - -

- Armour deck: 1.00" / 25 mm, Conning tower: 2.00" / 51 mm

Machinery:
Coal fired boilers, complex reciprocating steam engines,
Direct drive, 2 shafts, 12,254 ihp / 9,141 Kw = 20.00 kts
Range 3,000nm at 9.00 kts
Bunker at max displacement = 544 tons (100% coal)

Complement:
293 - 381

Cost:
£0.510 million / $2.042 million

Distribution of weights at normal displacement:
Armament: 25 tons, 0.5 %
Armour: 777 tons, 15.8 %
- Belts: 346 tons, 7.0 %
- Torpedo bulkhead: 185 tons, 3.8 %
- Armament: 45 tons, 0.9 %
- Armour Deck: 188 tons, 3.8 %
- Conning Tower: 12 tons, 0.3 %
Machinery: 2,375 tons, 48.3 %
Hull, fittings & equipment: 1,267 tons, 25.8 %
Fuel, ammunition & stores: 419 tons, 8.5 %
Miscellaneous weights: 50 tons, 1.0 %
10 TONS TORPEDOS (ONE SET OF RELOADS) + 15 TONS MEDIUM WT SET

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
1,840 lbs / 835 Kg = 62.2 x 4.0 " / 102 mm shells or 0.5 torpedoes
Stability (Unstable if below 1.00): 1.50
Metacentric height 3.6 ft / 1.1 m
Roll period: 11.1 seconds
Steadiness - As gun platform (Average = 50 %): 75 %
- Recoil effect (Restricted arc if above 1.00): 0.03
Seaboat quality (Average = 1.00): 1.25

Hull form characteristics:
Hull has a flush deck
Block coefficient: 0.521
Length to Beam Ratio: 6.00 : 1
'Natural speed' for length: 17.32 kts
Power going to wave formation at top speed: 57 %
Trim (Max stability = 0, Max steadiness = 100): 60
Bow angle (Positive = bow angles forward): 20.00 degrees
Stern overhang: 4.00 ft / 1.22 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 18.40 ft / 5.61 m
- Forecastle (20 %): 12.12 ft / 3.69 m
- Mid (50 %): 12.12 ft / 3.69 m
- Quarterdeck (15 %): 12.12 ft / 3.69 m
- Stern: 12.12 ft / 3.69 m
- Average freeboard: 12.62 ft / 3.85 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 268.9 %
- Above water (accommodation/working, high = better): 70.4 %
Waterplane Area: 10,189 Square feet or 947 Square metres
Displacement factor (Displacement / loading): 85 %
Structure weight / hull surface area: 77 lbs/sq ft or 376 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.91
- Longitudinal: 2.43
- Overall: 1.00
Hull space for machinery, storage, compartmentation is extremely poor
Room for accommodation and workspaces is cramped
Ship has slow, easy roll, a good, steady gun platform
Good seaboat, rides out heavy weather easily

[Borys]

Ahoj!
I kept the hull identical (both dimensions and BC), changed the engines for slightly more modern VTEs, and the displacements went crazy ...
BTW - I wonder about the cost of such a rebuild ...
And do I have enough deck space for all that?

SMS Graz, Habsburgs Kleiner Kreuzer laid down 1885 (Engine 1909)

Displacement:
   3 473 t light; 3 676 t standard; 5 087 t normal; 6 217 t full load

Dimensions: Length overall / water x beam x draught
   310,70 ft / 310,70 ft x 50,00 ft x 22,00 ft (normal load)
   94,70 m / 94,70 m x 15,24 m  x 6,71 m

Armament:
      8 - 6,00" / 152 mm guns in single mounts, 110,23lbs / 50,00kg shells, 1904 Model
     Breech loading guns in deck mounts with hoists
     on side, evenly spread
      2 - 3,00" / 76,2 mm guns in single mounts, 12,49lbs / 5,66kg shells, 1885 Model
     Quick firing guns in deck mounts
     on centreline, evenly spread
      4 - 0,43" / 11,0 mm guns in single mounts, 0,04lbs / 0,02kg shells, 1885 Model
     Machine guns in deck mounts
     on side, evenly spread
   Weight of broadside 907 lbs / 411 kg
   Shells per gun, main battery: 200
   4 - 20,0" / 508 mm above water torpedoes

Armour:
   - Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   2,00" / 51 mm   250,00 ft / 76,20 m   10,00 ft / 3,05 m
   Ends:   2,00" / 51 mm     50,00 ft / 15,24 m   10,00 ft / 3,05 m
     10,70 ft / 3,26 m Unarmoured ends
   Upper:   2,00" / 51 mm   250,00 ft / 76,20 m   5,00 ft / 1,52 m
     Main Belt covers 124% of normal length
     Main belt does not fully cover magazines and engineering spaces

   - Torpedo Bulkhead:
      1,00" / 25 mm   250,00 ft / 76,20 m   20,00 ft / 6,10 m

   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   2,00" / 51 mm         -         1,00" / 25 mm
   2nd:   1,00" / 25 mm         -               -
   3rd:   1,00" / 25 mm         -               -

   - Armour deck: 1,00" / 25 mm, Conning tower: 2,00" / 51 mm

Machinery:
   Coal fired boilers, complex reciprocating steam engines,
   Direct drive, 2 shafts, 11 693 ihp / 8 723 Kw = 20,00 kts
   Range 12 000nm at 12,00 kts
   Bunker at max displacement = 2 541 tons (100% coal)

Complement:
   300 - 391

Cost:
   £0,341 million / $1,363 million

Distribution of weights at normal displacement:
   Armament: 111 tons, 2,2%
   Armour: 801 tons, 15,8%
      - Belts: 348 tons, 6,8%
      - Torpedo bulkhead: 185 tons, 3,6%
      - Armament: 61 tons, 1,2%
      - Armour Deck: 195 tons, 3,8%
      - Conning Tower: 13 tons, 0,3%
   Machinery: 899 tons, 17,7%
   Hull, fittings & equipment: 1 511 tons, 29,7%
   Fuel, ammunition & stores: 1 615 tons, 31,7%
   Miscellaneous weights: 150 tons, 2,9%

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     5 826 lbs / 2 643 Kg = 58,3 x 6,0 " / 152 mm shells or 1,4 torpedoes
   Stability (Unstable if below 1.00): 1,27
   Metacentric height 2,7 ft / 0,8 m
   Roll period: 12,8 seconds
   Steadiness   - As gun platform (Average = 50 %): 70 %
         - Recoil effect (Restricted arc if above 1.00): 0,29
   Seaboat quality  (Average = 1.00): 1,21

Hull form characteristics:
   Hull has a flush deck
   Block coefficient: 0,521
   Length to Beam Ratio: 6,21 : 1
   'Natural speed' for length: 17,63 kts
   Power going to wave formation at top speed: 56 %
   Trim (Max stability = 0, Max steadiness = 100): 58
   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:      18,73 ft / 5,71 m
      - Forecastle (20%):   12,34 ft / 3,76 m
      - Mid (50%):      12,34 ft / 3,76 m
      - Quarterdeck (15%):   12,34 ft / 3,76 m
      - Stern:      12,34 ft / 3,76 m
      - Average freeboard:   12,85 ft / 3,92 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 131,1%
      - Above water (accommodation/working, high = better): 69,4%
   Waterplane Area: 10 552 Square feet or 980 Square metres
   Displacement factor (Displacement / loading): 140%
   Structure weight / hull surface area: 88 lbs/sq ft or 432 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0,91
      - Longitudinal: 2,44
      - Overall: 1,00
   Hull space for machinery, storage, compartmentation is cramped
   Room for accommodation and workspaces is cramped
   Ship has slow, easy roll, a good, steady gun platform
   Good seaboat, rides out heavy weather easily

[Walter]

I kept the hull identical (both dimensions and BC), changed the engines for slightly more modern VTEs, and the displacements went crazy ...

What do you expect when you go from 3,000nm at 9.00 kts (= 544 tons) to 12,000nm at 12.00 kts (= 2,541 tons). The bunker of the rebuild version is almost 5 times as big as the original 1885 design. Your light and standard displacements will drop severely while your full load will shoot up. Raise in normal displacement would be caused by the 10,70 feet increase of the length waterline.

[Borys]

Ahoj!
But, but ... the engine is lighter!
Borys

[Korpen]

Ahoj!
But, but ... the engine is lighter!
Borys

And? that has a fairly minor effect compared to the huge increase in fuel.
And like wlater pointed out, you have incrased the length of the ship.

[Borys]

Ahoj!
OK - I see it now - I took the old overall length and used it as the new WL lenght.
Will tinker with sim more ...
Borys

[Walter]

The engine is lighter

I would think that that is caused by technological advancement. I mean you put in engines that were made  24 years after the original. 24 long years for technicians to seriously improve the efficiency of the coal boilers and the VTEs.

[Borys]

Thanks, Walter and Korpen!

SMS Graz, Habsburgs Kleiner Kreuzer laid down 1885 (Engine 1909)
Old
Displacement:
4,493 t light; 4,610 t standard; 4,912 t normal; 5,154 t full load
New
Displacement:
3 382 t light; 3 582 t standard; 4 912 t normal; 5 976 t full load

Dimensions: Length overall / water x beam x draught
   300,00 ft / 300,00 ft x 50,00 ft x 22,00 ft (normal load)
   91,44 m / 91,44 m x 15,24 m  x 6,71 m

Armament:
      8 - 6,00" / 152 mm guns in single mounts, 110,23lbs / 50,00kg shells, 1904 Model
     Breech loading guns in deck mounts with hoists
     on side, evenly spread
      2 - 3,00" / 76,2 mm guns in single mounts, 13,00lbs / 5,90kg shells, 1885 Model
     Quick firing guns in deck mounts
     on centreline, evenly spread
      4 - 0,43" / 11,0 mm guns in single mounts, 0,04lbs / 0,02kg shells, 1885 Model
     Machine guns in deck mounts
     on side, evenly spread
   Weight of broadside 908 lbs / 412 kg
   Shells per gun, main battery: 200
   4 - 20,0" / 508 mm above water torpedoes

Armour:
   - Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   2,00" / 51 mm   250,00 ft / 76,20 m   10,00 ft / 3,05 m
   Ends:   2,00" / 51 mm     50,00 ft / 15,24 m   10,00 ft / 3,05 m
   Upper:   2,00" / 51 mm   250,00 ft / 76,20 m   5,00 ft / 1,52 m
     Main Belt covers 128% of normal length
     Main belt does not fully cover magazines and engineering spaces

   - Torpedo Bulkhead:
      1,00" / 25 mm   250,00 ft / 76,20 m   20,00 ft / 6,10 m

   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   2,00" / 51 mm   1,00" / 25 mm      1,00" / 25 mm
   2nd:   1,00" / 25 mm         -               -
   3rd:   1,00" / 25 mm         -               -

   - Armour deck: 1,00" / 25 mm, Conning tower: 2,00" / 51 mm

Machinery:
   Coal fired boilers, complex reciprocating steam engines,
   Direct drive, 2 shafts, 11 670 ihp / 8 706 Kw = 20,00 kts
   Range 11 500nm at 12,00 kts
   Bunker at max displacement = 2 394 tons (100% coal)

Complement:
   293 - 381

Cost:
   £0,337 million / $1,350 million

Distribution of weights at normal displacement:
   Armament: 111 tons, 2,3%
   Armour: 788 tons, 16,0%
      - Belts: 346 tons, 7,0%
      - Torpedo bulkhead: 185 tons, 3,8%
      - Armament: 57 tons, 1,2%
      - Armour Deck: 188 tons, 3,8%
      - Conning Tower: 12 tons, 0,3%
   Machinery: 898 tons, 18,3%
   Hull, fittings & equipment: 1 445 tons, 29,4%
   Fuel, ammunition & stores: 1 530 tons, 31,1%
   Miscellaneous weights: 140 tons, 2,8%

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     5 378 lbs / 2 440 Kg = 53,8 x 6,0 " / 152 mm shells or 1,4 torpedoes
   Stability (Unstable if below 1.00): 1,25
   Metacentric height 2,7 ft / 0,8 m
   Roll period: 12,9 seconds
   Steadiness   - As gun platform (Average = 50 %): 69 %
         - Recoil effect (Restricted arc if above 1.00): 0,29
   Seaboat quality  (Average = 1.00): 1,14

Hull form characteristics:
   Hull has a flush deck
   Block coefficient: 0,521
   Length to Beam Ratio: 6,00 : 1
   'Natural speed' for length: 17,32 kts
   Power going to wave formation at top speed: 57 %
   Trim (Max stability = 0, Max steadiness = 100): 60
   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:      18,40 ft / 5,61 m
      - Forecastle (20%):   12,12 ft / 3,69 m
      - Mid (50%):      12,12 ft / 3,69 m
      - Quarterdeck (15%):   12,12 ft / 3,69 m
      - Stern:      12,12 ft / 3,69 m
      - Average freeboard:   12,62 ft / 3,85 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 135,2%
      - Above water (accommodation/working, high = better): 66,9%
   Waterplane Area: 10 189 Square feet or 947 Square metres
   Displacement factor (Displacement / loading): 136%
   Structure weight / hull surface area: 88 lbs/sq ft or 430 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0,90
      - Longitudinal: 2,55
      - Overall: 1,00
   Hull space for machinery, storage, compartmentation is cramped
   Room for accommodation and workspaces is cramped

[swamphen]

One thing I do when I'm installing updated engines in Spring* is to, first thing, adjust the speed and range until the engine weight and bunkerage hit the same weight as in the original design. Then I "tone it down" as necessary to free up weight for other stuff.

This is especially useful for the bunkerage, as (I assume) this shows the "full bunkerage = same volume" weight. Then I can set for oil firing knowing everything will fit.

[P3D]

I usually follow the same procedure as Swamphen described when I am working on an engine refit.

[Carthaginian]

Swampy, I think, hit on the best, fastest way of doing it.

The most time consuming, but accurate way I think you could do it is look at the machinery weight and bunkerage tonnage, write them down, and try to match them with new engines.