Riverine Torpedo Boat

[The Rock Doctor]

I'm contemplating six of these to operate on the Amazon and Orinoco watersheds.  The CSA coastal gunboat with 12" guns was the original inspiration for this, but I likely face a Peruvian presence up-river at Iquitos.  The idea is, simply, to have a fast attack capability that can cause considerable damage to larger interlopers with their torpedoes.
 
This assumes, of course, that they can hit anything with their torpedoes.  I'm thinking that Gran Colombia has probably been charting the currents in the major branches of the Amazon, and might by now have some sort of "aiming table" that accounts for a current of a few knots such as might be found along the Amazon.  Still, accuracy will be a problem, so I've opted to go with greater numbers of smaller torpedos in the hopes that it improves the odds of a hit.  Even a 16" torpedo should ruin the day of a ship running up or down the Amazon.

I'd also think that a 16" torp, being shorter than an 18" torp, is less likely to strike the river bed upon launching, which is a bonus.

What think ye?  A worthy investment?  Am I better to use slightly deeper draft, older torpedo boats instead?  Or should I dump the torpedo-boat notion entirely and add gunboats/monitors?


Piranha v.6, laid down 1909

Displacement:
   236 t light; 242 t standard; 256 t normal; 268 t full load

Dimensions: Length overall / water x beam x draught
   214.82 ft / 213.25 ft x 20.34 ft x 4.92 ft (normal load)
   65.48 m / 65.00 m x 6.20 m  x 1.50 m

Armament:
      1 - 2.56" / 65.0 mm guns in single mounts, 8.38lbs / 3.80kg shells, 1909 Model
     Breech loading gun in a deck mount with hoist
     on centreline forward
      2 - 1.85" / 47.0 mm guns in single mounts, 3.17lbs / 1.44kg shells, 1909 Model
     Breech loading guns in deck mounts
     on side, all amidships
      2 - 0.31" / 8.0 mm guns in single mounts, 0.02lbs / 0.01kg shells, 1909 Model
     Machine guns in deck mounts
     on side, evenly spread
   Weight of broadside 15 lbs / 7 kg
   Shells per gun, main battery: 100
   4 - 16.0" / 406 mm above water torpedoes (two fixed forward on the bow, one twin carriage aft)

Armour:
   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   0.98" / 25 mm         -               -

Machinery:
   Coal and oil fired boilers, steam turbines,
   Direct drive, 2 shafts, 5,200 shp / 3,879 Kw = 25.53 kts
   Range 1,000nm at 10.00 kts (Bunkerage = 26 tons)

Complement:
   31 - 41

Cost:
   £0.028 million / $0.114 million

Distribution of weights at normal displacement:
   Armament: 2 tons, 0.7 %
   Armour: 1 tons, 0.5 %
      - Belts: 0 tons, 0.0 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 1 tons, 0.5 %
      - Armour Deck: 0 tons, 0.0 %
      - Conning Tower: 0 tons, 0.0 %
   Machinery: 133 tons, 52.1 %
   Hull, fittings & equipment: 89 tons, 34.8 %
   Fuel, ammunition & stores: 21 tons, 8.0 %
   Miscellaneous weights: 10 tons, 3.9 %
   -2 t:  torpedos
   -5 t:  wireless
   -3 t:  weight reserve

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     92 lbs / 42 Kg = 10.9 x 2.6 " / 65 mm shells or 0.1 torpedoes
   Stability (Unstable if below 1.00): 1.19
   Metacentric height 0.6 ft / 0.2 m
   Roll period: 10.7 seconds
   Steadiness   - As gun platform (Average = 50 %): 70 %
         - Recoil effect (Restricted arc if above 1.00): 0.13
   Seaboat quality  (Average = 1.00): 1.00

Hull form characteristics:
   Hull has a flush deck
   Block coefficient: 0.420
   Length to Beam Ratio: 10.48 : 1
   'Natural speed' for length: 14.60 kts
   Power going to wave formation at top speed: 64 %
   Trim (Max stability = 0, Max steadiness = 100): 70
   Bow angle (Positive = bow angles forward): 10.00 degrees
   Stern overhang: -3.28 ft / -1.00 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      8.86 ft / 2.70 m
      - Forecastle (20 %):   8.86 ft / 2.70 m
      - Mid (50 %):      8.86 ft / 2.70 m
      - Quarterdeck (15 %):   8.86 ft / 2.70 m
      - Stern:      8.86 ft / 2.70 m
      - Average freeboard:   8.86 ft / 2.70 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 177.8 %
      - Above water (accommodation/working, high = better): 93.0 %
   Waterplane Area: 2,704 Square feet or 251 Square metres
   Displacement factor (Displacement / loading): 47 %
   Structure weight / hull surface area: 18 lbs/sq ft or 87 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.50
      - Longitudinal: 1.72
      - 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

[Carthaginian]

Shoot, looks viable for coastal work as well.
I don't think that an 'aiming chart' would be necessary... any river rat worth his weight in pollywogs will know most of the currents, deep spots and shallows in his section of the river. They'd be able to tell that they needed to aim ahead or behind the target as necessary to compensate for the current.

Also, I think that the torpedoes could be given a 'quick fix' solution (like the Japanese attaching wooden fin extensions) in order to work on the run depth problem. :)

I really like her. The CSA might be well advised to work on something similar for the Gulf of Cortez and the Chesapeake.

[Borys]

Ahoj!
The problem with water rats on the Amazon is that most of old ones were killed by the Anuhuac, and Gran Colombians have been there for a grand total of three years or so.

Not sure if dedicated vessel needed, but it is nice.

Borys

[swamphen]

*waves hand* You want to build riverine battleships...
:D

Not a bad little boat, though.

[The Rock Doctor]

River battleships are okay in theory, but I've got limitations to deal with:

1)  Only type 0 drydocks

2)  Not wanting to needlessly alarm/provoke reactions from neighbours sharing the watershed

3)  Cost

This being said, I've got this design as well, but have no plans at this time to construct it:

Enter ship name, Enter country Enter ship type laid down 1909

Displacement:
   1,002 t light; 1,045 t standard; 1,119 t normal; 1,178 t full load

Dimensions: Length overall / water x beam x draught
   229.66 ft / 229.66 ft x 41.99 ft x 7.38 ft (normal load)
   70.00 m / 70.00 m x 12.80 m  x 2.25 m

Armament:
      2 - 5.51" / 140 mm guns in single mounts, 83.72lbs / 37.97kg shells, 1909 Model
     Breech loading guns in deck mounts with hoists
     on centreline ends, evenly spread
      2 - 5.51" / 140 mm guns in single mounts, 83.72lbs / 37.97kg shells, 1909 Model
     Breech loading guns in deck mounts with hoists
     on side, all amidships
      2 - 1.85" / 47.0 mm guns in single mounts, 3.17lbs / 1.44kg shells, 1909 Model
     Breech loading guns in deck mounts
     on side, evenly spread, all raised mounts
      2 - 0.31" / 8.0 mm guns in single mounts, 0.02lbs / 0.01kg shells, 1909 Model
     Breech loading guns in deck mounts
     on side, evenly spread, all raised mounts
   Weight of broadside 341 lbs / 155 kg
   Shells per gun, main battery: 100

Armour:
   - Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   2.95" / 75 mm   149.28 ft / 45.50 m   7.78 ft / 2.37 m
   Ends:   0.98" / 25 mm     80.35 ft / 24.49 m   7.78 ft / 2.37 m
     Main Belt covers 100 % of normal length

   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   0.98" / 25 mm         -         0.98" / 25 mm
   2nd:   0.98" / 25 mm         -         0.98" / 25 mm
   3rd:   0.39" / 10 mm         -               -
   4th:   0.39" / 10 mm         -               -

   - Armour deck: 0.98" / 25 mm, Conning tower: 2.95" / 75 mm

Machinery:
   Coal fired boilers, steam turbines,
   Direct drive, 2 shafts, 2,200 shp / 1,642 Kw = 15.87 kts
   Range 2,000nm at 10.00 kts (Bunkerage = 133 tons)

Complement:
   96 - 125

Cost:
   £0.086 million / $0.345 million

Distribution of weights at normal displacement:
   Armament: 43 tons, 3.8 %
   Armour: 318 tons, 28.4 %
      - Belts: 175 tons, 15.6 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 14 tons, 1.2 %
      - Armour Deck: 123 tons, 11.0 %
      - Conning Tower: 7 tons, 0.6 %
   Machinery: 110 tons, 9.8 %
   Hull, fittings & equipment: 507 tons, 45.3 %
   Fuel, ammunition & stores: 117 tons, 10.5 %
   Miscellaneous weights: 24 tons, 2.1 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     2,589 lbs / 1,175 Kg = 30.9 x 5.5 " / 140 mm shells or 1.3 torpedoes
   Stability (Unstable if below 1.00): 1.32
   Metacentric height 2.2 ft / 0.7 m
   Roll period: 11.8 seconds
   Steadiness   - As gun platform (Average = 50 %): 70 %
         - Recoil effect (Restricted arc if above 1.00): 0.22
   Seaboat quality  (Average = 1.00): 1.17

Hull form characteristics:
   Hull has a flush deck
   Block coefficient: 0.550
   Length to Beam Ratio: 5.47 : 1
   'Natural speed' for length: 15.15 kts
   Power going to wave formation at top speed: 50 %
   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:      11.81 ft / 3.60 m
      - Forecastle (20 %):   9.19 ft / 2.80 m
      - Mid (50 %):      9.19 ft / 2.80 m
      - Quarterdeck (15 %):   9.19 ft / 2.80 m
      - Stern:      9.19 ft / 2.80 m
      - Average freeboard:   9.40 ft / 2.86 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 63.7 %
      - Above water (accommodation/working, high = better): 122.7 %
   Waterplane Area: 6,731 Square feet or 625 Square metres
   Displacement factor (Displacement / loading): 124 %
   Structure weight / hull surface area: 59 lbs/sq ft or 288 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.93
      - Longitudinal: 1.83
      - Overall: 1.00
   Hull space for machinery, storage, compartmentation is excellent
   Room for accommodation and workspaces is excellent
   Ship has slow, easy roll, a good, steady gun platform

[Korpen]

River battleships are okay in theory, but I've got limitations to deal with:

1)  Only type 0 drydocks

2)  Not wanting to needlessly alarm/provoke reactions from neighbours sharing the watershed

3)  Cost

I might sounds odd, but I think she is under-armoured for a river battleship.
River fighting is very different from sea fighting, the main one is that the risk of coming under small-arms fire in much greater. Fire from field artillery and howitzers should not be discounted either. Due to this it would be best if all of the ship above water was enclosed in armour, with the weather deck being the armoured deck. The deck should be strong enough to withstand a 15cm HE shell from a howitzer, so 30-50mm thick. The same goes for the belt, strong enough to keep out the shells from most field artillery and light warships.

So maybe something like this monitor, armoured from top to 30cm under the waterline and two 47mm guns and two MGs capable of fire in any direction. She is cheap and hard to sink.

Enter ship name, Enter country Enter ship type laid down 1909

Displacement:
   697 t light; 730 t standard; 796 t normal; 849 t full load

Dimensions: Length overall / water x beam x draught
   164,04 ft / 164,04 ft x 32,81 ft x 6,56 ft (normal load)
   50,00 m / 50,00 m x 10,00 m  x 2,00 m

Armament:
      2 - 5,51" / 140 mm guns (1x2 guns), 83,72lbs / 37,98kg shells, 1909 Model
     Breech loading guns in Coles/Ericsson turret
     on centreline amidships
      8 - 1,85" / 47,0 mm guns in single mounts, 3,17lbs / 1,44kg shells, 1909 Model
     Quick firing guns in casemate mounts
     on side, evenly spread
     8 guns in hull casemates - Limited use in any sea
      8 - 0,31" / 8,0 mm guns in single mounts, 0,02lbs / 0,01kg shells, 1909 Model
     Machine guns in casemate mounts
     on side, evenly spread
     8 guns in hull casemates - Limited use in any sea
   Weight of broadside 193 lbs / 88 kg
   Shells per gun, main battery: 150

Armour:
   - Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   2,95" / 75 mm   164,04 ft / 50,00 m   6,89 ft / 2,10 m
   Ends:   Unarmoured
     Main Belt covers 154 % of normal length

   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   3,74" / 95 mm   3,74" / 95 mm            -
   2nd:   2,95" / 75 mm         -               -
   3rd:   2,95" / 75 mm         -               -

   - Armour deck: 1,97" / 50 mm, Conning tower: 2,95" / 75 mm

Machinery:
   Coal fired boilers, steam turbines,
   Direct drive, 2 shafts, 744 shp / 555 Kw = 12,00 kts
   Range 2 000nm at 10,00 kts
   Bunker at max displacement = 119 tons (100% coal)

Complement:
   74 - 97

Cost:
   £0,050 million / $0,199 million

Distribution of weights at normal displacement:
   Armament: 24 tons, 3,0 %
   Armour: 360 tons, 45,3 %
      - Belts: 123 tons, 15,5 %
      - Torpedo bulkhead: 0 tons, 0,0 %
      - Armament: 62 tons, 7,7 %
      - Armour Deck: 170 tons, 21,3 %
      - Conning Tower: 5 tons, 0,7 %
   Machinery: 37 tons, 4,7 %
   Hull, fittings & equipment: 255 tons, 32,1 %
   Fuel, ammunition & stores: 99 tons, 12,5 %
   Miscellaneous weights: 20 tons, 2,5 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     2 239 lbs / 1 016 Kg = 26,7 x 5,5 " / 140 mm shells or 1,6 torpedoes
   Stability (Unstable if below 1.00): 1,46
   Metacentric height 1,8 ft / 0,5 m
   Roll period: 10,3 seconds
   Steadiness   - As gun platform (Average = 50 %): 53 %
         - Recoil effect (Restricted arc if above 1.00): 0,12
   Seaboat quality  (Average = 1.00): 1,07

Hull form characteristics:
   Hull has a flush deck
   Block coefficient: 0,789
   Length to Beam Ratio: 5,00 : 1
   'Natural speed' for length: 12,81 kts
   Power going to wave formation at top speed: 50 %
   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:      5,91 ft / 1,80 m
      - Forecastle (20 %):   5,91 ft / 1,80 m
      - Mid (50 %):      5,91 ft / 1,80 m
      - Quarterdeck (15 %):   5,91 ft / 1,80 m
      - Stern:      5,91 ft / 1,80 m
      - Average freeboard:   5,91 ft / 1,80 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 42,6 %
      - Above water (accommodation/working, high = better): 70,8 %
   Waterplane Area: 4 660 Square feet or 433 Square metres
   Displacement factor (Displacement / loading): 123 %
   Structure weight / hull surface area: 45 lbs/sq ft or 220 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0,96
      - Longitudinal: 1,49
      - Overall: 1,00
   Hull space for machinery, storage, compartmentation is excellent
   Room for accommodation and workspaces is cramped

[The Rock Doctor]

Interesting - what exactly is a Coles-Ericcson turret, though?

[Borys]

Ahoj!
Read a techical description of the USS Monitor.
Borys

[Korpen]

As Borys said, a much older type of mounting, but in this case I thought it fitting as in does not really penetrate the deck in the same way as a barbarette would.

[Ithekro]

An armored turret with an unprotected mechanism below it to rotate the gun platform.  Most Union ironclads were fitted with these as were most 1869s to 1870s ironclads that had turrets.  They switched to open barbettes at some point then started using lightly armored hoods on some of them.  This lead to the fully armored turret and barbette combination we use now.

However a riverine warship does not have the draft to mount a barbette, nor does it really need one in most cases.  Thus an older style armored turret would be ideal for deflecting the average army-grade weaponry.  Mixed with a reasonable armored deck, some sort of all around belt (upper belt I would think as well) and an armored conning tower, the warship should be nearly immune to regular cannon and rifle fire.

[The Rock Doctor]

Thanks, Ithekro - that's what I needed to know; turret without a barbette.  That would be ideal for low-draft riverine craft. 

So, this being the case - what does the crowd think of Korpen's proposed riverine gunboat?

[Borys]

Ahoj!
No need for two guns. One, with more ammunition, is enough. The Amazon is a big place, and supply of ammunitioj could be a problem.
I'd even make it a howitzer. Maybe I'd put a QF 3 inch gun somewhere there too.

Borys

[swamphen]

The historical Amazon gunboats that Britian was building for Brazil (and took over at the start of WW1) might be an idea, as well.

[Korpen]

Thanks, Ithekro - that's what I needed to know; turret without a barbette.  That would be ideal for low-draft riverine craft. 

So, this being the case - what does the crowd think of Korpen's proposed riverine gunboat?

The best most brilliant ship ever made!

Well most likely not, I did not really intend her to be more then a illustration of the concept.
I am certain there are lots of little things that need tweaking on her to suite the specific specifications of the GC army or navy.