Iberia TB Designs of the 1920's

[ctwaterman]

Yes ramming a sub is a good way of sink the sub and the ship doing the ramming.
A few depth charges rolled off the side or stern as you run by the sub rather then ramming it might be a better idea especially in shallow warm shark infested waters....  :o ;D

[Sachmle]

IDK, I don't remember too many accounts of the ram-er being sunk as well as the ram-ie when it comes to DD/CL vs SS.

[miketr]

In WW1 of 178 UBoats KIA, 19 were sunk by ramming and 31 by depth charge.

[Sachmle]

In WW1 of 178 UBoats KIA, 19 were sunk by ramming and 31 by depth charge.

Guessing the other 128 fell to gunfire, running aground, *accidents*, ID10T errors by crew, etc..

[ctwaterman]

Mines mine mines and more mines....

Or the term Lost cause unknown...
Or Missing Presumed Lost

Charles

[miketr]

Source of sinking, doesn't how the source killed them.  Again all WW1

Patrol, HK groups and random encounter: 38
Convoy Escorts: 17
Q Ships: 11
Merchant ships: 6
Submarines: 18
Aircraft: 1
Mines: 48
Accidents: 19
Explosion, source unknown: 1
Cause Unknown: 19

Cause of sinking clearly known
Torpedoes: 18
Ramming: 19
Gunfire: 20
Depth Charges: 31

Other 90 cause is unknown or in dispute

[miketr]

I am going to build a new batch of small torpedo boats and I was refining the designs.  Should I build them in 334 tons or 250 ton designs?

TB-1920-S-250, Iberia Torpedo Boat laid down 1917 (Engine 1916)

Displacement:
   251 t light; 261 t standard; 292 t normal; 317 t full load

Dimensions: Length overall / water x beam x draught
   223.10 ft / 223.10 ft x 18.70 ft x 5.91 ft (normal load)
   68.00 m / 68.00 m x 5.70 m  x 1.80 m

Armament:
      1 - 4.13" / 105 mm guns in single mounts, 35.32lbs / 16.02kg shells, 1917 Model
     Quick firing gun in deck mount
     on centreline forward
      1 - 2.95" / 75.0 mm guns in single mounts, 12.87lbs / 5.84kg shells, 1917 Model
     Anti-aircraft gun in deck mounts
     on side, all amidships, 1 raised gun
   Weight of broadside 48 lbs / 22 kg
   Shells per gun, main battery: 130
   4 - 21.0" / 533.4 mm above water torpedoes

Armour:
   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   0.79" / 20 mm         -               -

Machinery:
   Oil fired boilers, steam turbines,
   Geared drive, 2 shafts, 9,501 shp / 7,087 Kw = 29.21 kts
   Range 1,500nm at 15.00 kts
   Bunker at max displacement = 57 tons

Complement:
   34 - 45

Cost:
   £0.063 million / $0.254 million

Distribution of weights at normal displacement:
   Armament: 6 tons, 2.1 %
   Armour: 2 tons, 0.6 %
      - Belts: 0 tons, 0.0 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 2 tons, 0.6 %
      - Armour Deck: 0 tons, 0.0 %
      - Conning Tower: 0 tons, 0.0 %
   Machinery: 151 tons, 51.5 %
   Hull, fittings & equipment: 79 tons, 26.9 %
   Fuel, ammunition & stores: 41 tons, 14.1 %
   Miscellaneous weights: 14 tons, 4.8 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     61 lbs / 28 Kg = 1.7 x 4.1 " / 105 mm shells or 0.1 torpedoes
   Stability (Unstable if below 1.00): 1.14
   Metacentric height 0.5 ft / 0.2 m
   Roll period: 10.9 seconds
   Steadiness   - As gun platform (Average = 50 %): 38 %
         - Recoil effect (Restricted arc if above 1.00): 0.19
   Seaboat quality  (Average = 1.00): 0.40

Hull form characteristics:
   Hull has rise forward of midbreak
   Block coefficient: 0.415
   Length to Beam Ratio: 11.93 : 1
   'Natural speed' for length: 14.94 kts
   Power going to wave formation at top speed: 68 %
   Trim (Max stability = 0, Max steadiness = 100): 74
   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:      10.17 ft / 3.10 m
      - Forecastle (20 %):   9.02 ft / 2.75 m
      - Mid (50 %):      7.87 ft / 2.40 m (4.59 ft / 1.40 m aft of break)
      - Quarterdeck (15 %):   4.59 ft / 1.40 m
      - Stern:      4.59 ft / 1.40 m
      - Average freeboard:   6.73 ft / 2.05 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 187.1 %
      - Above water (accommodation/working, high = better): 31.4 %
   Waterplane Area: 2,592 Square feet or 241 Square metres
   Displacement factor (Displacement / loading): 38 %
   Structure weight / hull surface area: 18 lbs/sq ft or 88 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.50
      - Longitudinal: 0.76
      - Overall: 0.52
   Hull space for machinery, storage, compartmentation is cramped
   Room for accommodation and workspaces is extremely poor
   Caution: Lacks seaworthiness - very limited seakeeping ability

Four 21" (2 t) Torpedos (4 x 2) 8 tons
15 Depth Charges 5 tons
Construction Reserve 1 tons

Trial Speed: 33.9

TB-1920-S-333, Iberia Torpedo Boat  laid down 1920 (Engine 1916)

Displacement:
   334 t light; 345 t standard; 396 t normal; 437 t full load

Dimensions: Length overall / water x beam x draught
   218.27 ft / 216.54 ft x 19.69 ft x 6.56 ft (normal load)
   66.53 m / 66.00 m x 6.00 m  x 2.00 m

Armament:
      1 - 4.13" / 105 mm guns in single mounts, 35.32lbs / 16.02kg shells, 1920 Model
     Breech loading gun in deck mount
     on centreline forward
      1 - 2.95" / 75.0 mm guns in single mounts, 12.87lbs / 5.84kg shells, 1920 Model
     Anti-aircraft gun in deck mount
     on centreline aft
   Weight of broadside 48 lbs / 22 kg
   Shells per gun, main battery: 130
   4 - 21.0" / 533 mm above water torpedoes

Armour:
   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   0.79" / 20 mm         -               -

Machinery:
   Oil fired boilers, steam turbines,
   Geared drive, 2 shafts, 15,001 shp / 11,191 Kw = 30.36 kts
   Range 1,975nm at 15.00 kts
   Bunker at max displacement = 92 tons
     Caution: Delicate, lightweight machinery

Complement:
   43 - 57

Cost:
   £0.110 million / $0.441 million

Distribution of weights at normal displacement:
   Armament: 6 tons, 1.5 %
   Armour: 2 tons, 0.4 %
      - Belts: 0 tons, 0.0 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 2 tons, 0.4 %
      - Armour Deck: 0 tons, 0.0 %
      - Conning Tower: 0 tons, 0.0 %
   Machinery: 214 tons, 54.0 %
   Hull, fittings & equipment: 99 tons, 25.0 %
   Fuel, ammunition & stores: 63 tons, 15.8 %
   Miscellaneous weights: 13 tons, 3.3 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     79 lbs / 36 Kg = 2.2 x 4.1 " / 105 mm shells or 0.1 torpedoes
   Stability (Unstable if below 1.00): 1.11
   Metacentric height 0.5 ft / 0.2 m
   Roll period: 11.4 seconds
   Steadiness   - As gun platform (Average = 50 %): 34 %
         - Recoil effect (Restricted arc if above 1.00): 0.17
   Seaboat quality  (Average = 1.00): 0.28

Hull form characteristics:
   Hull has a flush deck
   Block coefficient: 0.496
   Length to Beam Ratio: 11.00 : 1
   'Natural speed' for length: 14.72 kts
   Power going to wave formation at top speed: 74 %
   Trim (Max stability = 0, Max steadiness = 100): 81
   Bow angle (Positive = bow angles forward): 10.00 degrees
   Stern overhang: 0.00 ft / 0.00 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      9.84 ft / 3.00 m
      - Forecastle (15 %):   9.35 ft / 2.85 m
      - Mid (34 %):      9.02 ft / 2.75 m
      - Quarterdeck (10 %):   4.92 ft / 1.50 m
      - Stern:      4.92 ft / 1.50 m
      - Average freeboard:   7.57 ft / 2.31 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 189.2 %
      - Above water (accommodation/working, high = better): 33.5 %
   Waterplane Area: 2,830 Square feet or 263 Square metres
   Displacement factor (Displacement / loading): 34 %
   Structure weight / hull surface area: 20 lbs/sq ft or 97 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.50
      - Longitudinal: 1.03
      - Overall: 0.54
   Hull space for machinery, storage, compartmentation is cramped
   Room for accommodation and workspaces is extremely poor
   Caution: Lacks seaworthiness - very limited seakeeping ability

Four 21" (2 t) Torpedos (4 x 2) 8 tons
21 Depth Charges 7 tons

Trial Speed: 34.07 Knots

[maddox]

1 75mm AA gun, it seems the rift war scared everybody about aircraft.

[ciders]

Why a single 75 mm gun and not two or three lighter guns or machine guns ? After all, it is above all a light torpedo boat, not a heavy antiaircraft vessel.

[Guinness]

A boat this small will be a poor barrage AA platform. MGs or machine cannon might be a better choice. I suspect the legs on both of these are little bit short. What's there range at the SS max speed?

Also 4 TTs on a 250t boat seems like a lot.

[miketr]

1 75mm AA gun, it seems the rift war scared everybody about aircraft.

Why a single 75 mm gun and not two or three lighter guns or machine guns ? After all, it is above all a light torpedo boat, not a heavy antiaircraft vessel.

Its the only AA gun I have.

[ciders]

Yes, but... destroy a group of agile planes who attack with their machine guns, with a huge single 75 mm ? 

So much attack a column of ants by throwing her rocks.

[miketr]

[/quote]

Yes, but... destroy a group of agile planes who attack with their machine guns, with a huge single 75 mm ? 

So much attack a column of ants by throwing her rocks.

Look at AA weapons of the time period.  Putting huge numbers of automatic weapons is VERY unhistoric. 

[miketr]

A boat this small will be a poor barrage AA platform. MGs or machine cannon might be a better choice. I suspect the legs on both of these are little bit short. What's there range at the SS max speed?

Also 4 TTs on a 250t boat seems like a lot.

For the 250 ton

Range
29.2 knots = 220 nm
25 knots = 350 nm
20 knots = 700 nm

For the 334 ton
Range
30.4 knots = 230 nm
25 knots = 440 nm
20 knots = 870 nm

As to Torpedo Tubes...  Our light torpedo boats are fairly unhistorical to be honest and all I am doing is putting a single mount on the ships, the largest sized mount I can have mind you.  If people think its too large then I can of course reduce.

Michael

[ciders]

I agree. But 75 mm on MTB, is it possible ?