River Gunboat

[Kaiser Kirk]

So, the new spot in Africa has a fairly large river -the Ruvuma - with some tributaries.  It's 500 miles long and has inhabited islands.
During the dry season, the river does get shallow enough to ford in spots, as it also gets a mile wide down low.

So, I've toyed with a gunboat design.
Thought about making it a paddlewheel, but unsure how to best do that.
It's an armored barge with a forward 75mm howitzer, and an aft Gardner 45-70 HMG.  4 x 7.5mm MMG anchor the superstructure.

It's modeled with a bulge 0.1m away from the hull, it's unarmored, but 6mm of metal "pay" for the double hull.
Likewise the 12mm deck is really 6mm armor, with a double bottom- again 6mm extra.
These should guard against riverine protrusions.

There are 80tons misc weight. I figure part is AC, part is a Winch, and part is a Marine Squad/ explorers quarters.

So, any glaring flaws, or just better ideas?

Tortoise, Italian River Gunboat laid down 1902 (Engine 1900)

Displacement:
   200 t light; 205 t standard; 209 t normal; 212 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (104.99 ft / 101.71 ft) x 19.69 ft (Bulges 20.34 ft) x (5.05 / 5.12 ft)
   (32.00 m / 31.00 m) x 6.00 m (Bulges 6.20 m)  x (1.54 / 1.56 m)

Armament:
      1 - 2.95" / 75.0 mm 21.0 cal gun - 11.57lbs / 5.25kg shells, 120 per gun
     Breech loading gun in deck mount, 1902 Model
     1 x Single mount on centreline aft
      2 - 0.41" / 10.4 mm 94.0 cal guns - 0.07lbs / 0.03kg shells, 1,500 per gun
     Machine guns in deck mount, 1902 Model
     1 x Twin mount on sides amidships
      4 - 0.30" / 7.5 mm 45.0 cal guns - 0.01lbs / 0.00kg shells, 1,500 per gun
     Machine guns in deck mounts, 1902 Model
     4 x Single mounts on sides, evenly spread
      4 double raised mounts
      Weight of broadside 12 lbs / 5 kg

Armour:
   - Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   0.24" / 6 mm     50.85 ft / 15.50 m   5.31 ft / 1.62 m
   Ends:   0.24" / 6 mm     50.82 ft / 15.49 m   5.31 ft / 1.62 m
   Upper:   0.24" / 6 mm     50.85 ft / 15.50 m   6.96 ft / 2.12 m
     Main Belt covers 77 % of normal length

   - Hull Bulges:
      0.24" / 6 mm     98.43 ft / 30.00 m   5.05 ft / 1.54 m

   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   0.39" / 10 mm         -               -
   2nd:   0.28" / 7 mm   0.28" / 7 mm            -

   - Armoured deck - multiple decks: 0.47" / 12 mm For and Aft decks
   Forecastle: 0.47" / 12 mm  Quarter deck: 0.47" / 12 mm

   - Conning towers: Forward 0.24" / 6 mm,  Aft 0.00" / 0 mm

Machinery:
   Coal fired boilers, simple reciprocating steam engines,
   No drive to shaft, 2 shafts, 145 ihp / 109 Kw = 9.50 kts
   Range 650nm at 6.00 kts
   Bunker at max displacement = 7 tons (100% coal)

Complement:
   26 - 35

Cost:
   £0.011 million / $0.044 million

Distribution of weights at normal displacement:
   Armament: 1 tons, 0.6 %
   Armour: 36 tons, 17.0 %
      - Belts: 10 tons, 4.6 %
      - Bulges: 4 tons, 2.1 %
      - Armament: 7 tons, 3.5 %
      - Armour Deck: 14 tons, 6.8 %
      - Conning Tower: 0 tons, 0.1 %
   Machinery: 26 tons, 12.3 %
   Hull, fittings & equipment: 58 tons, 27.6 %
   Fuel, ammunition & stores: 9 tons, 4.2 %
   Miscellaneous weights: 80 tons, 38.3 %
      - Hull below water: 40 tons
      - Hull above water: 25 tons
      - On freeboard deck: 15 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     425 lbs / 193 Kg = 33.0 x 3.0 " / 75 mm shells or 0.5 torpedoes
   Stability (Unstable if below 1.00): 1.49
   Metacentric height 0.9 ft / 0.3 m
   Roll period: 9.2 seconds
   Steadiness   - As gun platform (Average = 50 %): 100 %
         - Recoil effect (Restricted arc if above 1.00): 0.05
   Seaboat quality  (Average = 1.00): 2.00

Hull form characteristics:
   Hull has a flush deck,
     a ram bow and a cruiser stern
   Block coefficient (normal/deep): 0.700 / 0.701
   Length to Beam Ratio: 5.00 : 1
   'Natural speed' for length: 10.08 kts
   Power going to wave formation at top speed: 49 %
   Trim (Max stability = 0, Max steadiness = 100): 50
   Bow angle (Positive = bow angles forward): -15.00 degrees
   Stern overhang: -3.28 ft / -1.00 m
   Freeboard (% = length of deck as a percentage of waterline length):
            Fore end,    Aft end
      - Forecastle:   25.00 %,  7.05 ft / 2.15 m,  7.05 ft / 2.15 m
      - Forward deck:   25.00 %,  7.05 ft / 2.15 m,  7.05 ft / 2.15 m
      - Aft deck:   25.00 %,  7.05 ft / 2.15 m,  7.05 ft / 2.15 m
      - Quarter deck:   25.00 %,  7.05 ft / 2.15 m,  7.05 ft / 2.15 m
      - Average freeboard:      7.05 ft / 2.15 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 76.5 %
      - Above water (accommodation/working, high = better): 82.9 %
   Waterplane Area: 1,605 Square feet or 149 Square metres
   Displacement factor (Displacement / loading): 122 %
   Structure weight / hull surface area: 24 lbs/sq ft or 117 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.87
      - Longitudinal: 3.54
      - Overall: 1.00
   Hull space for machinery, storage, compartmentation is excellent
   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

[eltf177]

Machinery:
   Coal fired boilers, simple reciprocating steam engines,
   No drive to shaft, 2 shafts, 145 ihp / 109 Kw = 9.50 kts <------
   Range 650nm at 6.00 kts
   Bunker at max displacement = 7 tons (100% coal)

Need to fix this...

[Walter]

So, the new spot in Africa has a fairly large river -the Ruvuma - with some tributaries.  It's 500 miles long and has inhabited islands.

Sounds like a good enough reason to set the range at 1000 miles then, even if a large part can't be navigated. :)

During the dry season, the river does get shallow enough to ford in spots, as it also gets a mile wide down low.

... so is 1.56m shallow enough?

Looking a bit furter, as eltf177 pointed out the drive unless they use oars to move the boat. Seaboat quality  of 2 is just wasted on a river vessel. Personally I would like something with less freeboard making the vessel a bit smaller target for idiots with guns on the shores of the river.

[The Rock Doctor]

I agree that the draught and freeboard may be excessive.

[Kaiser Kirk]

Ok, lowered the freeboard, cut the draft by 1/3...to 1.1m, which had a drastic effect on comp hull. Upped range to 1200nm.  Lowered speed to compensate.
So it's a 250t version, but otherwise similar.
Oh, and it has a drive shaft now.

Tortoise, Italian River Gunboat laid down 1902 (Engine 1900)

Displacement:
   249 t light; 255 t standard; 261 t normal; 266 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (137.80 ft / 134.51 ft) x 26.25 ft (Bulges 26.90 ft) x (3.61 / 3.67 ft)
   (42.00 m / 41.00 m) x 8.00 m (Bulges 8.20 m)  x (1.10 / 1.12 m)

Armament:
      1 - 2.95" / 75.0 mm 21.0 cal gun - 11.57lbs / 5.25kg shells, 120 per gun
     Breech loading gun in deck mount, 1902 Model
     1 x Single mount on centreline aft
      2 - 0.41" / 10.4 mm 94.0 cal guns - 0.07lbs / 0.03kg shells, 1,500 per gun
     Machine guns in deck mount, 1902 Model
     1 x Twin mount on sides amidships
      4 - 0.30" / 7.5 mm 45.0 cal guns - 0.01lbs / 0.00kg shells, 1,500 per gun
     Machine guns in deck mounts, 1902 Model
     4 x Single mounts on sides, evenly spread
      4 double raised mounts
      Weight of broadside 12 lbs / 5 kg

Armour:
   - Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   0.28" / 7 mm     67.26 ft / 20.50 m   6.14 ft / 1.87 m
   Ends:   0.28" / 7 mm     67.22 ft / 20.49 m   6.14 ft / 1.87 m
   Upper:   0.28" / 7 mm     67.26 ft / 20.50 m   4.72 ft / 1.44 m
     Main Belt covers 77 % of normal length

   - Hull Bulges:
      0.24" / 6 mm     98.43 ft / 30.00 m   3.61 ft / 1.10 m

   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   0.39" / 10 mm         -               -
   2nd:   0.28" / 7 mm   0.28" / 7 mm            -
   3rd:   0.28" / 7 mm         -               -

   - Armoured deck - multiple decks: 0.51" / 13 mm For and Aft decks
   Forecastle: 0.51" / 13 mm  Quarter deck: 0.51" / 13 mm

   - Conning towers: Forward 0.28" / 7 mm,  Aft 0.00" / 0 mm

Machinery:
   Coal fired boilers, simple reciprocating steam engines,
   Direct drive, 2 shafts, 92 ihp / 69 Kw = 8.00 kts
   Range 1,200nm at 5.00 kts
   Bunker at max displacement = 10 tons (100% coal)

Complement:
   32 - 42

Cost:
   £0.011 million / $0.046 million

Distribution of weights at normal displacement:
   Armament: 1 tons, 0.4 %
   Armour: 55 tons, 21.0 %
      - Belts: 14 tons, 5.4 %
      - Bulges: 3 tons, 2.1 %
      - Armament: 10 tons, 4.0 %
      - Armour Deck: 27 tons, 10.3 %
      - Conning Tower: 0 tons, 0.1 %
   Machinery: 16 tons, 6.2 %
   Hull, fittings & equipment: 89 tons, 34.0 %
   Fuel, ammunition & stores: 12 tons, 4.5 %
   Miscellaneous weights: 88 tons, 33.7 %
      - Hull below water: 48 tons
      - Hull above water: 25 tons
      - On freeboard deck: 15 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     828 lbs / 376 Kg = 64.3 x 3.0 " / 75 mm shells or 0.9 torpedoes
   Stability (Unstable if below 1.00): 1.89
   Metacentric height 1.9 ft / 0.6 m
   Roll period: 8.3 seconds
   Steadiness   - As gun platform (Average = 50 %): 52 %
         - Recoil effect (Restricted arc if above 1.00): 0.01
   Seaboat quality  (Average = 1.00): 1.05

Hull form characteristics:
   Hull has a flush deck,
     a ram bow and a cruiser stern
   Block coefficient (normal/deep): 0.700 / 0.701
   Length to Beam Ratio: 5.00 : 1
   'Natural speed' for length: 11.60 kts
   Power going to wave formation at top speed: 29 %
   Trim (Max stability = 0, Max steadiness = 100): 50
   Bow angle (Positive = bow angles forward): -15.00 degrees
   Stern overhang: -3.28 ft / -1.00 m
   Freeboard (% = length of deck as a percentage of waterline length):
            Fore end,    Aft end
      - Forecastle:   25.00 %,  4.72 ft / 1.44 m,  4.72 ft / 1.44 m
      - Forward deck:   25.00 %,  4.72 ft / 1.44 m,  4.72 ft / 1.44 m
      - Aft deck:   25.00 %,  4.72 ft / 1.44 m,  4.72 ft / 1.44 m
      - Quarter deck:   25.00 %,  4.72 ft / 1.44 m,  4.72 ft / 1.44 m
      - Average freeboard:      4.72 ft / 1.44 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 53.4 %
      - Above water (accommodation/working, high = better): 79.6 %
   Waterplane Area: 2,830 Square feet or 263 Square metres
   Displacement factor (Displacement / loading): 146 %
   Structure weight / hull surface area: 27 lbs/sq ft or 131 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 1.00
      - Longitudinal: 1.03
      - Overall: 1.00
   Hull space for machinery, storage, compartmentation is excellent
   Room for accommodation and workspaces is cramped

2nd Battery Shell weight too heavy

Propulsion :
It takes 20hp to steam at 5knts.


Miscellaneous Weight

On Deck
10t - big winches fore& aft with lots of chain
5t - Pachinko machines

Hull Above Water
5t - Forced air ventilation for ship (no AC this early)
10t - Sick bay & dedicated Corpman
10t - Repair shop & stores

Below Water
16t - Space and storage for 4 "Explorers"
20t - Space and storage for 10 Marines
12t - Cargo Hold

The 75/21 is a light Howitzer, which can be used for direct or indirect fire.

Armor : 6mm of Bulge and "Armor deck" represent a double hull and bottom, 0.1m away from the main hull and bottom.   7mm of armor is actual armor laid on top of hull steel, , intended to represent a bulletproof hull - particularly against the old trade rifles one would find in Africa.

[Jefgte]

0.249BP ...

Too expensive ship.

Test  0.1BP

Jef

[The Rock Doctor]

0.249BP ...

Too expensive ship.

Test  0.1BP

Jef

I don't agree with that - you'd have a far less capable hull.

Air ventilation seems a luxury, and the weight of gun armor seems high for the quantity indicated.

The double hull and simple machinery make sense in the absence of port infrastructure.

[Walter]

I don't agree with that - you'd have a far less capable hull.

True but it really depends on the requirements. I have two river gunboat designs. One of 117 tons (light) armed with a pair of 75mm guns and 6 gatling guns, 20mm armored hull and 10mm armored deck and another of 90 tons (light) with a single 60mm gun and 23 gatling guns (yes, the baddies on the shores of the rivers will most likely die from a severe case of lead poisoning), 20mm armored hull and 10mm armored deck.

... but that is it. It does not have big winches with lots of chain, no Pachinko machines, no forced air ventilation, no sickbay, no repair shop and stores, no space for explorers or marines who are too lazy to walk or swim and no space for cargo. They are just boats to move along the rivers and turn any idiot who wants to take a shot at one of those boats into Swiss Cheese. That's it. Nothing more needed from them. Same thing with the 18 ton river patrol boat.

Kirk has 88 tons of miscellaneous weights for all those things and that weight requires additional 'Hull, fittings & equipment' weight to support it. Also the draught is your best source for hull strength so lowering it means that he had to make the boat even bigger. So for what he wants from the boat, I think that 249 tons is acceptable.

Air ventilation seems a luxury, and the weight of gun armor seems high for the quantity indicated.

I think so, too. No need to go soft on your sailors. :)

... as for the gun armor, why do the 10.4 mm guns required 'Other gunhouse' armor? Also I would think that if you go for a twin mount it is better to have it on the centerline and not on one of the sides.

[eltf177]

Personally I'd put it on the bow myself...

[Walter]

If you are attacking, yes. If you are running away, it is better to have it aft.  :)

[Kaiser Kirk]

Thanks for the comments.
To address the concerns -

Background : The Italians went shopping for a bit of territory they could get to (East Africa is easier), was unclaimed, actually had growing things (unlike Somalia) and had a chance of something of value ( Portuguese East Africa, the Orange Free State and South Africa have stuff, perhaps this does). There's 500 years of trade here, and 70 years of limited exploration. By 1900 they know there's a very big river and some big tributaries, and no roads.  Which means waterways are key, and any population centers are probably not to far off.

So a gunboat such as I presented vs. a bunch of "barbarians" (the 1900 Italians view native Africans as such, which gets into the entire ranking of races typical of the time) with spears, arrows and probably old muskets....well it can rule the river.
One advantage of the original design was an 2m freeboard would be really hard to board from a canoe.

Size - For 0.250 I can build a destroyer, or a riverboat. I kinda need the latter more.

Gun location : Fixed....The Gardner MG was supposed to be bow, and so exposed, and the howitzer stern and exposed to fire.

Gun armor :  The idea is that KC armor plate wins vs. bow & muzzle loading rifles.
But, if there are two banks and you're facing one, they may just shoot you from the other one.  So I've given the howitzer a gun house as well. It's not an issue for the 7.5 MGs as they have the bulk of the superstructure behind them.

Forced Air - it IS a luxury.  I'm in the US Pacific NW. I think of Africa as HOT HOT HOT.
I'm guessing the Italians just think of it as HOT HOT.

In reality, it's really pretty temperate there, kinda similar to Italy, and better as you get to the highlands.  So it's a waste that way.  But a completely armored vessel tends to have few scuttles, or other means of moving air below decks...and hot humid air sitting in a steel box for months is...ugh.  So, the forced air has the secondary idea of putting a breeze below decks and keeping the boiler stokers from falling over or "ill humors" building up.

Winch - They really don't know what they are getting into, but whatever it is, they will be totally on their own. So if they run onto a sandbar, or need to pull logs onto a dry stretch to serve as rollers, they can.

Workshop - same.

Marines/Explorers. - Usually, you learn more when you get off the boat and look around :) 

Pachinko Machines - an easter egg for Walter :)

[The Rock Doctor]

Makes sense.

I'd venture, at least, that 2% of displacement is excessive for costing the air ventilation - you're talking about something that is mostly hollow duct work.

It's neat to see somebody else doing riverboats.  Interesting to compare where we go as this moves forward.

[Kaiser Kirk]

The funny thing is I started somewhere very different than your R-1 class and wound up with something very similar.
The initial, unposted, renditions had a coastal/riverine gunboat, and one file was entitled Ironclad as I've always liked the US Civil War vessels.
Once I found out that the River got broad and shallow in the summer - something that should be "known" once traders are talked to- the draft had to get shallower....and shallower...
and the tonnage meant I couldn't have double ended howitzers....

[Walter]

So a gunboat such as I presented vs. a bunch of "barbarians" (the 1900 Italians view native Africans as such, which gets into the entire ranking of races typical of the time) with spears, arrows and probably old muskets....well it can rule the river.

Just give 'em the bayonet. Like Corporal Jones said, 'They don't like it up 'em, sir!'. ;D

But, if there are two banks and you're facing one, they may just shoot you from the other one.  So I've given the howitzer a gun house as well. It's not an issue for the 7.5 MGs as they have the bulk of the superstructure behind them.

Right now I only see a gunhouse on the 10.4 mm MG turret. The howitzer is in an open mount so those gunners will end up with arrows in their pants.

I'm in the US Pacific NW. I think of Africa as HOT HOT HOT.

In July or August, take the plane to Phoenix and leave the airport. Hittting that wall of heat will probably give you an idea about how hot it might be. :)

Winch - They really don't know what they are getting into, but whatever it is, they will be totally on their own. So if they run onto a sandbar, or need to pull logs onto a dry stretch to serve as rollers, they can.

That was one reason I thought the ship should have a bit less draught. While it can still happen, with your current 1.12 m maximum, you are less likely to get stuck in shallow waters than with your initial 1.56 m.

Pachinko Machines - an easter egg for Walter

Yes I noticed them, butl I'm not sure China has them, though I did put them on Wesworld ships... and IIRC they were introduced in the 1920s or 30s so I doubt you have the proper tech to install them. :D

... maybe you should add a few pasta and pizza vending machines as well to the mix. ;D

[Kaiser Kirk]

"Summer" i.e. February, ranges from 22-31 C / 72-88F for modern Mozambique and 25-31C for Tanzania. All of which   Compares decently with Southern Italy at 26-28C.  Malawi varies, with much of it maxing at 23-25C and lakeside 27-29C.

Malaria will be an issue, but the name is Italian,  it was around in ancient  Roman times and they've had cinchona bark/quinine to treat it since the 1600s, though the Italians probably use the Austrian Warburg's Tincture. Professor Grassi in Rome just in 1898 proved only Anopheles could transmit. 
The new Italian stomping grounds are at the very edges of the Yellow Fever zone mapped, so probably safeish.