Egyptian Design Studies 1912-1913

[Talos]

Here's a riverine gunboat I've been fiddling with based on the steam GB Na'am I inherited. It's meant to be a study to see what I can do with 750hp ICE engines and what I can build immediately, limiting me to 6" and 3" cannons.


GB Study 01, Egypt Large River Gunboat laid down 1912

Displacement:
   462 t light; 496 t standard; 506 t normal; 514 t full load

Dimensions: Length overall / water x beam x draught
   120.00 ft / 120.00 ft x 28.00 ft x 8.50 ft (normal load)
   36.58 m / 36.58 m x 8.53 m  x 2.59 m

Armament:
      2 - 6.00" / 152 mm guns in single mounts, 108.00lbs / 48.99kg shells, 1912 Model
     Quick firing guns in deck mounts with hoists
     on centreline ends, evenly spread
      4 - 3.00" / 76.2 mm guns in single mounts, 13.50lbs / 6.12kg shells, 1912 Model
     Quick firing guns in deck mounts with hoists
     on side, all amidships
      8 - 0.50" / 12.7 mm guns in single mounts, 0.06lbs / 0.03kg shells, 1912 Model
     Quick firing guns in deck mounts
     on side, evenly spread
   Weight of broadside 270 lbs / 123 kg
   Shells per gun, main battery: 150

Armour:
   - Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   4.00" / 102 mm     40.00 ft / 12.19 m   5.00 ft / 1.52 m
   Ends:   Unarmoured
     Main Belt covers 51 % of normal length
     Main belt does not fully cover magazines and engineering spaces

   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   6.00" / 152 mm         -               -
   2nd:   2.00" / 51 mm         -               -

   - Armour deck: 0.50" / 13 mm, Conning tower: 6.00" / 152 mm

Machinery:
   Diesel Internal combustion motors,
   Direct drive, 3 shafts, 2,002 shp / 1,493 Kw = 16.00 kts
   Range 500nm at 10.00 kts
   Bunker at max displacement = 18 tons

Complement:
   53 - 69

Cost:
   £0.054 million / $0.218 million

Distribution of weights at normal displacement:
   Armament: 34 tons, 6.7 %
   Armour: 133 tons, 26.3 %
      - Belts: 47 tons, 9.4 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 54 tons, 10.7 %
      - Armour Deck: 23 tons, 4.6 %
      - Conning Tower: 8 tons, 1.6 %
   Machinery: 70 tons, 13.9 %
   Hull, fittings & equipment: 205 tons, 40.4 %
   Fuel, ammunition & stores: 44 tons, 8.7 %
   Miscellaneous weights: 20 tons, 4.0 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     512 lbs / 232 Kg = 4.7 x 6.0 " / 152 mm shells or 0.4 torpedoes
   Stability (Unstable if below 1.00): 1.00
   Metacentric height 0.7 ft / 0.2 m
   Roll period: 13.6 seconds
   Steadiness   - As gun platform (Average = 50 %): 26 %
         - Recoil effect (Restricted arc if above 1.00): 0.64
   Seaboat quality  (Average = 1.00): 0.26

Hull form characteristics:
   Hull has a flush deck
   Block coefficient: 0.620
   Length to Beam Ratio: 4.29 : 1
   'Natural speed' for length: 10.95 kts
   Power going to wave formation at top speed: 74 %
   Trim (Max stability = 0, Max steadiness = 100): 51
   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:      12.05 ft / 3.67 m
      - Forecastle (20 %):   7.67 ft / 2.34 m
      - Mid (50 %):      7.67 ft / 2.34 m
      - Quarterdeck (15 %):   7.67 ft / 2.34 m
      - Stern:      7.67 ft / 2.34 m
      - Average freeboard:   8.02 ft / 2.44 m

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 101.3 %
      - Above water (accommodation/working, high = better): 69.0 %
   Waterplane Area: 2,504 Square feet or 233 Square metres
   Displacement factor (Displacement / loading): 87 %
   Structure weight / hull surface area: 56 lbs/sq ft or 271 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.84
      - Longitudinal: 4.82
      - Overall: 1.00
   Hull space for machinery, storage, compartmentation is adequate
   Room for accommodation and workspaces is cramped
   Ship has quick, lively roll, not a steady gun platform
   Caution: Lacks seaworthiness - very limited seakeeping ability

[Talos]

And study number 2, a steam-powered one.

GB Study 02 "Mini-mac", Egypt Large River Gunboat laid down 1912

Displacement:
   753 t light; 780 t standard; 797 t normal; 811 t full load

Dimensions: Length overall / water x beam x draught
   150.00 ft / 150.00 ft x 30.00 ft x 10.00 ft (normal load)
   45.72 m / 45.72 m x 9.14 m  x 3.05 m

Armament:
      2 - 3.00" / 76.2 mm guns in single mounts, 13.50lbs / 6.12kg shells, 1912 Model
     Quick firing guns in casemate mounts
     on centreline ends, evenly spread
      6 - 3.00" / 76.2 mm guns in single mounts, 13.50lbs / 6.12kg shells, 1912 Model
     Quick firing guns in casemate mounts
     on side, evenly spread
      8 - 0.50" / 12.7 mm guns in single mounts, 0.06lbs / 0.03kg shells, 1912 Model
     Quick firing guns in deck mounts
     on side, evenly spread
   Weight of broadside 108 lbs / 49 kg
   Shells per gun, main battery: 150

Armour:
   - Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   6.00" / 152 mm     50.00 ft / 15.24 m   7.00 ft / 2.13 m
   Ends:   Unarmoured
     Main Belt covers 51 % of normal length
     Main belt does not fully cover magazines and engineering spaces

   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   6.00" / 152 mm         -               -
   2nd:   6.00" / 152 mm         -               -

   - Armour deck: 0.50" / 13 mm, Conning tower: 6.00" / 152 mm

Machinery:
   Coal fired boilers, complex reciprocating steam engines,
   Direct drive, 2 shafts, 2,931 ihp / 2,186 Kw = 17.00 kts
   Range 500nm at 10.00 kts
   Bunker at max displacement = 31 tons (100% coal)

Complement:
   74 - 97

Cost:
   £0.065 million / $0.260 million

Distribution of weights at normal displacement:
   Armament: 14 tons, 1.7 %
   Armour: 234 tons, 29.4 %
      - Belts: 119 tons, 14.9 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 73 tons, 9.2 %
      - Armour Deck: 31 tons, 3.9 %
      - Conning Tower: 11 tons, 1.4 %
   Machinery: 194 tons, 24.3 %
   Hull, fittings & equipment: 291 tons, 36.5 %
   Fuel, ammunition & stores: 44 tons, 5.6 %
   Miscellaneous weights: 20 tons, 2.5 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     1,033 lbs / 469 Kg = 76.5 x 3.0 " / 76 mm shells or 0.5 torpedoes
   Stability (Unstable if below 1.00): 1.02
   Metacentric height 0.9 ft / 0.3 m
   Roll period: 13.6 seconds
   Steadiness   - As gun platform (Average = 50 %): 88 %
         - Recoil effect (Restricted arc if above 1.00): 0.22
   Seaboat quality  (Average = 1.00): 1.18

Hull form characteristics:
   Hull has a flush deck
   Block coefficient: 0.620
   Length to Beam Ratio: 5.00 : 1
   'Natural speed' for length: 12.25 kts
   Power going to wave formation at top speed: 70 %
   Trim (Max stability = 0, Max steadiness = 100): 75
   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:      12.05 ft / 3.67 m
      - Forecastle (20 %):   12.05 ft / 3.67 m
      - Mid (50 %):      12.05 ft / 3.67 m
      - Quarterdeck (15 %):   12.05 ft / 3.67 m
      - Stern:      12.05 ft / 3.67 m
      - Average freeboard:   12.05 ft / 3.67 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 95.6 %
      - Above water (accommodation/working, high = better): 104.0 %
   Waterplane Area: 3,353 Square feet or 312 Square metres
   Displacement factor (Displacement / loading): 106 %
   Structure weight / hull surface area: 50 lbs/sq ft or 244 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 1.01
      - Longitudinal: 8.29
      - Overall: 1.25
   Hull space for machinery, storage, compartmentation is adequate
   Room for accommodation and workspaces is adequate
   Ship has slow, easy roll, a good, steady gun platform

[P3D]

You have to consider that the Nile is not a very  wide river - about the same size as the Danube in say Belgrade. 3m is a bit too deep IMHO.

[Talos]

I did, actually. The Nile is rather deep (I've been up it before). It's about 3km wide on average, and somewhere between 8 and 11 meters deep. I could probably cut down on the draft though some.

[The Rock Doctor]

Nice to see some more river boats.

The belts on these boats are quite a bit shorter than SS wants...

I'm inclined to swap out some of the 3" on each of the designs for a smaller QF gun, something in the 40-50mm range - seem more useful for plinking at shore targets or unprotected riverine vessels.

[Talos]

Thanks, Rock.

The main reason I went with 3" guns is that I'm trying to lay these down in 1912 (I'm working on the HY reports for those right now) too fill some of my spare BP since I really don't have anything else to build. The only guns that would fit on a river vessel that I have available immediately are:

6"
3"
and .5"

So I've limited them to those weapons. The Study 1 is intended to see just what I can do with those diesel engines I have access to, the Study 2 is supposed to be like a casemate ironclad-like vessel like the old CSS Virginia. I figure it'd be a fine type for river warfare. Low, armored, etc.

[Korpen]

I do not see much need for naval riverboats on a river that one de facto controls in it entirety.
That said: I think both the boats would improve if the armour was thinned, but made much more extensive. As the mouth of the river is under solid Egyptian control, there is a very little threat from enemy ships with heavy high-velocity guns. A greater threat would then be enemy army units that penetrated to the Nile and the kind of artillery such units would have. This means that the ship should be protected against ~75mm shrapnel shells and ~11cm howitzer shells with AP ammo being unlikely.  This makes me think that armour in the 4cm+ (both deck and belt) thickness with maximum coverage would be the best, rather then the very thick but small belts of the designs you posted.

Think I once said something similar about GC river gunboats for the Amazon...
EDIT: http://www.navalism.org/index.php?topic=1352.msg12546#msg12546

[Talos]

The river gunboats have a triple purpose for Egypt. They're to provide fire-support along the coastline and on ships on the river, police the river, and bolster defense of Alexandria and Cairo harbors.

Maddox, as usual, came up with a better ship in a matter of minutes. I tweaked it some, mostly getting rid of the 1" guns (which Egypt doesn't have), replacing them with .5" ones, and modifying the freeboard and armor. The 6" guns are howitzers, designed to reach inland from the shores.

al-Sayyid, Egypt Large River Gunboat laid down 1912

Displacement:
   976 t light; 997 t standard; 1,044 t normal; 1,082 t full load

Dimensions: Length overall / water x beam x draught
   229.66 ft / 229.66 ft x 39.37 ft x 6.56 ft (normal load)
   70.00 m / 70.00 m x 12.00 m  x 2.00 m

Armament:
      2 - 6.00" / 152 mm guns in single mounts, 108.00lbs / 48.99kg shells, 1912 Model
     Breech loading guns in deck mounts with hoists
     on centreline ends, evenly spread
      6 - 3.00" / 76.2 mm guns in single mounts, 13.50lbs / 6.12kg shells, 1912 Model
     Quick firing guns in deck mounts
     on side, evenly spread
      4 - 0.50" / 12.7 mm guns in single mounts, 0.06lbs / 0.03kg shells, 1912 Model
     Machine guns in deck mounts
     on side, evenly spread, all raised mounts
   Weight of broadside 297 lbs / 135 kg
   Shells per gun, main battery: 0

Armour:
   - Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   5.00" / 127 mm   100.28 ft / 30.57 m   7.00 ft / 2.13 m
   Ends:   Unarmoured
     Main Belt covers 67 % of normal length

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

   - Armour deck: 1.25" / 32 mm

Machinery:
   Diesel Internal combustion motors,
   Direct drive, 3 shafts, 2,250 shp / 1,679 Kw = 16.00 kts
   Range 2,000nm at 10.00 kts
   Bunker at max displacement = 85 tons

Complement:
   91 - 119

Cost:
   £0.078 million / $0.312 million

Distribution of weights at normal displacement:
   Armament: 37 tons, 3.6 %
   Armour: 352 tons, 33.7 %
      - Belts: 173 tons, 16.6 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 23 tons, 2.2 %
      - Armour Deck: 155 tons, 14.9 %
      - Conning Tower: 0 tons, 0.0 %
   Machinery: 90 tons, 8.6 %
   Hull, fittings & equipment: 478 tons, 45.7 %
   Fuel, ammunition & stores: 68 tons, 6.5 %
   Miscellaneous weights: 20 tons, 1.9 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     3,184 lbs / 1,444 Kg = 29.5 x 6.0 " / 152 mm shells or 1.5 torpedoes
   Stability (Unstable if below 1.00): 1.33
   Metacentric height 2.1 ft / 0.6 m
   Roll period: 11.5 seconds
   Steadiness   - As gun platform (Average = 50 %): 69 %
         - Recoil effect (Restricted arc if above 1.00): 0.23
   Seaboat quality  (Average = 1.00): 1.38

Hull form characteristics:
   Hull has a flush deck
   Block coefficient: 0.616
   Length to Beam Ratio: 5.83 : 1
   'Natural speed' for length: 15.15 kts
   Power going to wave formation at top speed: 50 %
   Trim (Max stability = 0, Max steadiness = 100): 50
   Bow angle (Positive = bow angles forward): -5.00 degrees
   Stern overhang: 0.00 ft / 0.00 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      16.67 ft / 5.08 m
      - Forecastle (20 %):   10.61 ft / 3.23 m
      - Mid (50 %):      10.61 ft / 3.23 m
      - Quarterdeck (15 %):   10.61 ft / 3.23 m
      - Stern:      10.61 ft / 3.23 m
      - Average freeboard:   11.09 ft / 3.38 m

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 55.8 %
      - Above water (accommodation/working, high = better): 149.1 %
   Waterplane Area: 6,712 Square feet or 624 Square metres
   Displacement factor (Displacement / loading): 123 %
   Structure weight / hull surface area: 54 lbs/sq ft or 262 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.92
      - Longitudinal: 2.20
      - Overall: 1.01
   Hull space for machinery, storage, compartmentation is excellent
   Room for accommodation and workspaces is excellent
   Good seaboat, rides out heavy weather easily

[The Rock Doctor]

Generally speaking, I like it - although she's probably four to six knots faster than she needs to be.

You still need to specify the main battery ammunition count.

Korpen's comments about deck versus belt armor on gunboats is worth noting.  Additionally, although in practical terms the ship only has 56% of its hull used for vital stuff, your belt length only works if you're cramming the howitzers amidships.

[Talos]

Oh, that does remind me. They were crammed amidships originally, I accidentally moved them to the ends.

Basically, the ship is intended to supplement and replace the Na'am, so the speed is intended to let it go 12 knots either up or downstream (Na'am's speed), since the Nile has a 4 knot northern current.

I'll continue to tweak the armor placement though, I'm not satisfied with it yet. I also forgot to include this (it's accounted in the SS though):

Misc Weight:
20 tons-Tropicization, fans, ducting and ventilation.

[Korpen]

About howitzers, i think you should sim them as ~105mm guns, but with the real shell weight (~40kg), as this would take inte account  the much lower weight and power of a howitzer compared to a gun.

EDIT: Springshar put the weight of a single 105mm gun at 4,415 tons.
Most 15 cm howitzers was in the 3-3,5 ton range, with some as heavy as four ton, and some as low as 2 and bit.

[Guinness]

Would the howitzers need to be researched as a naval gun, or are we presuming they are coming from already existing army stocks?

[The Rock Doctor]

I don't think we want a special howitzer tech.  Just assume any reasonable army equipment for the era is available.

[Talos]

Maddox and I were talking about it a few days ago and our initial idea was a naval gun in a high-angle mounting, which would give nice range ashore, as well as larger shell size. I could easily replace them with Army howitzers though, probably around 75mm or so.

[Korpen]

Maddox and I were talking about it a few days ago and our initial idea was a naval gun in a high-angle mounting, which would give nice range ashore, as well as larger shell size. I could easily replace them with Army howitzers though, probably around 75mm or so.

An army 75mm howitzer on a ship? Why not a gun instead? The shrapnell shell from a howitzer is pretty useless and the HE shells from so smalle a weapon are not really any good either. Also weight is not that big a deal on a boat, it does not matter all that much if using a 1,2 ton gun or a 600kg howitzer while a range of ~5km or around 8km does matter.