Vilnius Union Ships, 1920+: Electric Drive Boogaloo

[The Rock Doctor]

https://www.usni.org/magazines/naval-history-magazine/2022/february/great-idea-defeated-physics

Mentions 20 t for a cage versus 90 for a tripod.  Apparently cages were more susceptible to vibrations and shocks (fast ships with big guns) than tripods, which I did not know.  Not that it's an issue on this particular design; in fact, it's probably an intentional design consideration and not just me blindly responding to Kirk's challenge.

[Kaiser Kirk]

The article I was speaking about is :

http://www.gwpda.org/naval/cagvtrip.htm

Vibration in this document appears to be a toss up, varying by vessel.

My understanding is that as FC became heavier, the acceptable vibration and whip
in cages masts increased, and so they wound up replaced eventually,
but this report was apparently after, and perhaps in response to the failure of USS Michigan's masts in a hurricane.

But as you say - not an issue here.

20 vs 23 tons... the section below gives 23 tons, but that "contemplates" light plating... which I take to mean it wasn't yet fitted. So 20 might be the initial weight.

The pertinent portion is :
Weight. - The comparison of weight given on page 5, enclosure (B) [not reproduced], is from the latest information available as regards the wieght of the foremast on H.M.S. HOOD. No absolutely accurate weights are available, but it can be safely said that the totoal weight of the tripod mast, including struts, mast, topmast, spotters' tops, defense, platform, etc., but not including the decks below the searchlight platform, os at least 100 tons. The increase in the size of the spotters' top, due to increasing the size of the range finders, increasing the diameter of the struts, and making the revolving hood for the 15" rangefinder and 15" director tower power-driven.

The total weight of about 23 tons for a single cage-mast for Battleships 49 to 51 given on page 5 of enclosure (B) [not reproduced], contemplates light plating for the sides of the spotters' top and director tower. For special treatment steel side plating the total weight would be increased about 4 tons. This weight provides for 3" x 1/4" tube, whereas in the old design of cage-mast the tube was 3" x 1/8".

[TacCovert4]

Hurricanes are one reason for my decision to go queen Anne mansions.  Because while it creates more sail area, it encases much of the superstructure in a weather protected box, and it has plenty of structural rigidity. 

[The Rock Doctor]

My little tub would certainly not be popular during a hurricane.

[Kaiser Kirk]

The discussion does touch on Michagan's and says that the safety factor on those masts had been reduced from 2.0 to nil,
though it's not made clear if that was a maintenance issue, or an added weight issue or both, but that failure
was not viewed as cause for alarm. 
Plus in a hurricane, one could argue the more weight high above the deck, the worse, so a 100 ton structure may not be better.
Interesting little side jaunt.

[The Rock Doctor]

Maybe I'll assign a couple tonnes to pyrotechnic bolts that eject the entire cage mast in case of emerg...never mind.

[The Rock Doctor]

Alternate take on the harbour patrol boat.  Most significantly, it's got a bit of protection, and that means it's mil-spec and not mercantile construction.  So full cost, whereas previous builds have all been cheap and mercantile.

Enter ship name, Enter country Enter ship type laid down 1925

Displacement:
   55 t light; 57 t standard; 58 t normal; 59 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (82.12 ft / 78.74 ft) x 13.12 ft x (3.94 / 3.98 ft)
   (25.03 m / 24.00 m) x 4.00 m  x (1.20 / 1.21 m)

Armament:
      1 - 1.97" / 50.0 mm 45.0 cal gun - 3.85lbs / 1.75kg shells, 150 per gun
     Quick firing gun in deck mount, 1925 Model
     1 x Single mount on centreline ends, evenly spread
      2 - 0.59" / 15.0 mm 90.0 cal guns - 0.12lbs / 0.05kg shells, 4,000 per gun
     Machine guns in deck mounts, 1925 Model
     1 x Single mount on centreline, forward deck aft
      1 raised mount - superfiring
     1 x Single mount on centreline, aft deck centre
      Weight of broadside 4 lbs / 2 kg

Armour:
   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   0.79" / 20 mm   0.12" / 3 mm            -
   2nd:   0.59" / 15 mm         -               -

   - Conning towers: Forward 0.79" / 20 mm,  Aft 0.00" / 0 mm

Machinery:
   Diesel Internal combustion motors,
   Geared drive, 2 shafts, 402 shp / 300 Kw = 14.78 kts
   Range 300nm at 10.00 kts
   Bunker at max displacement = 2 tons

Complement:
   9 - 13

Cost:
   £0.013 million / $0.053 million

Distribution of weights at normal displacement:
   Armament: 1 tons, 1.8 %
   Armour: 3 tons, 5.6 %
      - Armament: 3 tons, 5.2 %
      - Conning Tower: 0 tons, 0.4 %
   Machinery: 13 tons, 22.4 %
   Hull, fittings & equipment: 18 tons, 31.6 %
   Fuel, ammunition & stores: 3 tons, 5.4 %
   Miscellaneous weights: 19 tons, 33.0 %
      - Hull below water: 12 tons
      - On freeboard deck: 6 tons
      - Above deck: 1 tons

Fittings:
-7 t:  D-E drive, BW
-5 t:  Basic Hydrophone Paackage, BW
-2-4 t:  Depth charges, FD
-2-4 t:  Passengers or deck cargo, FD
-1 t:  Searchlight, AD

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     72 lbs / 33 Kg = 18.9 x 2.0 " / 50 mm shells or 0.2 torpedoes
   Stability (Unstable if below 1.00): 1.19
   Metacentric height 0.3 ft / 0.1 m
   Roll period: 9.6 seconds
   Steadiness   - As gun platform (Average = 50 %): 70 %
         - Recoil effect (Restricted arc if above 1.00): 0.12
   Seaboat quality  (Average = 1.00): 1.30

Hull form characteristics:
   Hull has a flush deck,
     a normal bow and a cruiser stern
   Block coefficient (normal/deep): 0.500 / 0.502
   Length to Beam Ratio: 6.00 : 1
   'Natural speed' for length: 8.87 kts
   Power going to wave formation at top speed: 71 %
   Trim (Max stability = 0, Max steadiness = 100): 54
   Bow angle (Positive = bow angles forward): 10.00 degrees
   Stern overhang: 1.64 ft / 0.50 m
   Freeboard (% = length of deck as a percentage of waterline length):
            Fore end,    Aft end
      - Forecastle:   20.00 %,  9.84 ft / 3.00 m,  7.87 ft / 2.40 m
      - Forward deck:   20.00 %,  7.87 ft / 2.40 m,  5.91 ft / 1.80 m
      - Aft deck:   45.00 %,  5.91 ft / 1.80 m,  5.91 ft / 1.80 m
      - Quarter deck:   15.00 %,  5.91 ft / 1.80 m,  5.91 ft / 1.80 m
      - Average freeboard:      6.65 ft / 2.03 m

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 102.0 %
      - Above water (accommodation/working, high = better): 90.5 %
   Waterplane Area: 688 Square feet or 64 Square metres
   Displacement factor (Displacement / loading): 113 %
   Structure weight / hull surface area: 13 lbs/sq ft or 63 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.58
      - Longitudinal: 8.57
      - Overall: 0.76
   Caution: Hull subject to strain in open-sea
   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
   Good seaboat, rides out heavy weather easily

[Kaiser Kirk]

Alternate take on the harbour patrol boat.  Most significantly, it's got a bit of protection, and that means it's mil-spec and not mercantile construction.  So full cost, whereas previous builds have all been cheap and mercantile.

Good amount of things crammed in there.

Hmm now I have to go back and look at my little 60ton river gunboat and see where we differ. I'm guessing you are much faster.
I am annoyed with myself, I forgot to research diesels and so am doing so now, but my diesel designs have to wait.
...hmm that was easy to find... top of page 20 of my design thread.
So, yes you are much faster. I designed mine so 2 can be built in a 50m dock (20+10+20) which makes them round...err tubby.
15mm vs. 20mm armor, oil-sprayed coal fired turbo-electric, so room to rebuild with diesel.  Much heavier gun armed as it's meant to be a mil-spec river gunboat,
not harbor patrol.
Curious to see two microvessels, I haven't done much in that size class since my original 60t steam torpedo boats.

[The Rock Doctor]

I've found that I usually have a bunch of larger slips available and can just allocate three to a 100m dock and meet my needs most of the time.  The current use of individual 50m slips is because I'm pausing MTB builds.

The HPBs can and probably do have a secondary riverine role, but I have a large number of dedicated riverboats in the 80-140 t range and I'm considering options for replacing them with something in that same size range.

[TacCovert4]

The discussion does touch on Michagan's and says that the safety factor on those masts had been reduced from 2.0 to nil,
though it's not made clear if that was a maintenance issue, or an added weight issue or both, but that failure
was not viewed as cause for alarm. 
Plus in a hurricane, one could argue the more weight high above the deck, the worse, so a 100 ton structure may not be better.
Interesting little side jaunt.

The other thing with the Michigan is that it's an SC Class.  The USN wanted to build a Dreadnought, but Congress (damn them) had restricted cost/tonnage to be no more than the previous Pre-Dread class.  So they had to build a Dreadnought on a shoestring......which meant they went for the absolute minimums on anything that wasn't an absolutely vital system.

[The Rock Doctor]

Possible "baseline" armored river gunboat that could replace similar sized hulls from the 1890s.

I contemplated a shorter 15mm belt combined with a 20mm box as protection, but opted to go with the more conventional 20mm belt and full deck.  The notion is more about protecting the waterline and the important bits from splinters and small arms fire than from direct shell hits.

Also contemplated trying to shove a 50mm AA mounting in but that isn't practical if I want to keep the size down.  The two twin HMG mountings will have to do that job.

Enter ship name, Enter country Enter ship type laid down 1926

Displacement:
   80 t light; 87 t standard; 88 t normal; 89 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (101.96 ft / 98.43 ft) x 16.40 ft x (3.61 / 3.65 ft)
   (31.08 m / 30.00 m) x 5.00 m  x (1.10 / 1.11 m)

Armament:
      1 - 2.95" / 75.0 mm 40.0 cal gun - 12.34lbs / 5.60kg shells, 250 per gun
     Breech loading gun in deck mount, 1926 Model
     1 x Single mount on centreline, aft deck centre
      1 - 2.95" / 75.0 mm 45.0 cal gun - 12.98lbs / 5.89kg shells, 250 per gun
     Quick firing gun in deck mount, 1926 Model
     1 x Single mount on centreline, forward deck centre
      4 - 0.59" / 15.0 mm 90.0 cal guns - 0.12lbs / 0.05kg shells, 4,000 per gun
     Anti-air guns in deck mounts, 1926 Model
     2 x Twin mounts on sides, aft deck forward
      2 raised mounts
      Weight of broadside 26 lbs / 12 kg

Armour:
   - Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   0.79" / 20 mm     62.34 ft / 19.00 m   4.92 ft / 1.50 m
   Ends:   Unarmoured
     Main Belt covers 97 % of normal length

   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   0.98" / 25 mm   0.59" / 15 mm            -
   2nd:   0.98" / 25 mm   0.59" / 15 mm            -
   4th:   0.59" / 15 mm         -               -

   - Armoured deck - single deck: 0.79" / 20 mm For and Aft decks
   Forecastle: 0.59" / 15 mm  Quarter deck: 0.59" / 15 mm

   - Conning towers: Forward 0.79" / 20 mm,  Aft 0.00" / 0 mm

Machinery:
   Diesel Internal combustion motors,
   Geared drive, 2 shafts, 301 shp / 225 Kw = 13.27 kts
   Range 300nm at 10.00 kts
   Bunker at max displacement = 3 tons

Complement:
   13 - 18

Cost:
   £0.019 million / $0.077 million

Distribution of weights at normal displacement:
   Armament: 5 tons, 5.3 %
   Armour: 36 tons, 40.3 %
      - Belts: 11 tons, 12.1 %
      - Armament: 9 tons, 10.2 %
      - Armour Deck: 16 tons, 17.7 %
      - Conning Tower: 0 tons, 0.4 %
   Machinery: 10 tons, 10.9 %
   Hull, fittings & equipment: 24 tons, 27.7 %
   Fuel, ammunition & stores: 8 tons, 8.9 %
   Miscellaneous weights: 6 tons, 6.8 %
      - Hull below water: 3 tons
      - On freeboard deck: 1 tons
      - Above deck: 2 tons

Fittings:
-3t:  Diesel engines (BW)
-1 t:  Weight reserve/deck cargo (FD)
-1 t:  FC, such as it is (AD)
-1 t:  Searchlight (AD)

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     177 lbs / 80 Kg = 13.7 x 3.0 " / 75 mm shells or 0.4 torpedoes
   Stability (Unstable if below 1.00): 1.23
   Metacentric height 0.5 ft / 0.1 m
   Roll period: 9.9 seconds
   Steadiness   - As gun platform (Average = 50 %): 70 %
         - Recoil effect (Restricted arc if above 1.00): 0.25
   Seaboat quality  (Average = 1.00): 1.00

Hull form characteristics:
   Hull has a flush deck,
     a normal bow and a cruiser stern
   Block coefficient (normal/deep): 0.530 / 0.532
   Length to Beam Ratio: 6.00 : 1
   'Natural speed' for length: 9.92 kts
   Power going to wave formation at top speed: 60 %
   Trim (Max stability = 0, Max steadiness = 100): 70
   Bow angle (Positive = bow angles forward): 10.00 degrees
   Stern overhang: 1.97 ft / 0.60 m
   Freeboard (% = length of deck as a percentage of waterline length):
            Fore end,    Aft end
      - Forecastle:   15.00 %,  8.86 ft / 2.70 m,  6.89 ft / 2.10 m
      - Forward deck:   15.00 %,  6.89 ft / 2.10 m,  4.92 ft / 1.50 m
      - Aft deck:   55.00 %,  4.92 ft / 1.50 m,  4.92 ft / 1.50 m
      - Quarter deck:   15.00 %,  4.92 ft / 1.50 m,  4.92 ft / 1.50 m
      - Average freeboard:      5.48 ft / 1.67 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 59.0 %
      - Above water (accommodation/working, high = better): 83.2 %
   Waterplane Area: 1,106 Square feet or 103 Square metres
   Displacement factor (Displacement / loading): 119 %
   Structure weight / hull surface area: 17 lbs/sq ft or 82 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.67
      - Longitudinal: 2.12
      - Overall: 0.75
   Caution: Hull subject to strain in open-sea
   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

[TacCovert4]

I'm a bit confused as to the 75mm breechloader and the 75mm quick fire.

I completely agree that you don't need a heavy AA suite on a boat like this. 

My thoughts, skip having two 3in guns that are slightly different.  And go with a single larger gun.  This is a riverboat, a lot of its job will be supporting troops.  The boat means it can easily carry artillery you can't haul around off road.  It also means you have a gun that'll fire more rapidly than a field gun, and will fire with more precision than a field gun, and with more endurance given the depth of the boat's magazine.

[The Rock Doctor]

Whoops.  The 40cal breechloader is a howitzer deal.  Yeah, the barrel should be shorter, but that's what I specified at startup and haven't developed one since.

[The Rock Doctor]

Broke:  Sverige with 4x11" guns

Woke:  Sverige with 4x17.7" guns

Misc. weight is mainly fire control, command facilities, and the usual wireless/searchlight fightings.  There's weight for a plane on deck but I have doubts that there's deckspace for it.

Note that I haven't settled on the weight of the 450mm shell just yet, so it could get heavier.  That's the default there.



Enter ship name, Enter country Enter ship type laid down 1926

Displacement:
   18,892 t light; 20,092 t standard; 21,504 t normal; 22,633 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (489.84 ft / 485.56 ft) x 98.43 ft x (26.25 / 27.38 ft)
   (149.30 m / 148.00 m) x 30.00 m  x (8.00 / 8.34 m)

Armament:
      4 - 17.72" / 450 mm 45.0 cal guns - 2,804.10lbs / 1,271.92kg shells, 100 per gun
     Breech loading guns in turret on barbette mounts, 1926 Model
     2 x Single mounts on centreline, evenly spread
      8 - 5.91" / 150 mm 45.0 cal guns - 103.86lbs / 47.11kg shells, 250 per gun
     Breech loading guns in turret on barbette mounts, 1926 Model
     4 x 2-gun mounts on sides, evenly spread
      6 - 3.94" / 100.0 mm 45.0 cal guns - 30.77lbs / 13.96kg shells, 300 per gun
     Anti-air guns in deck mounts, 1926 Model
     6 x 2-gun mounts on centreline, evenly spread
      Weight of broadside 12,232 lbs / 5,548 kg

Armour:
   - Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   7.48" / 190 mm   315.62 ft / 96.20 m   16.37 ft / 4.99 m
   Ends:   Unarmoured
     Main Belt covers 100 % of normal length

   - Torpedo Bulkhead:
      1.57" / 40 mm   315.62 ft / 96.20 m   24.74 ft / 7.54 m

   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   15.7" / 400 mm   7.87" / 200 mm      15.0" / 380 mm
   2nd:   3.94" / 100 mm   1.97" / 50 mm      3.94" / 100 mm
   3rd:   0.79" / 20 mm   0.79" / 20 mm            -

   - Armoured deck - multiple decks: 3.94" / 100 mm For and Aft decks
   Forecastle: 0.00" / 0 mm  Quarter deck: 3.94" / 100 mm

   - Conning towers: Forward 3.94" / 100 mm,  Aft 0.00" / 0 mm

Machinery:
   Oil fired boilers, steam turbines,
   Geared drive, 2 shafts, 45,043 shp / 33,602 Kw = 23.00 kts
   Range 16,400nm at 10.00 kts
   Bunker at max displacement = 2,541 tons

Complement:
   887 - 1,154

Cost:
   £6.894 million / $27.576 million

Distribution of weights at normal displacement:
   Armament: 2,393 tons, 11.1 %
   Armour: 6,741 tons, 31.3 %
      - Belts: 1,766 tons, 8.2 %
      - Torpedo bulkhead: 455 tons, 2.1 %
      - Armament: 2,115 tons, 9.8 %
      - Armour Deck: 2,339 tons, 10.9 %
      - Conning Tower: 66 tons, 0.3 %
   Machinery: 1,442 tons, 6.7 %
   Hull, fittings & equipment: 7,817 tons, 36.4 %
   Fuel, ammunition & stores: 2,611 tons, 12.1 %
   Miscellaneous weights: 500 tons, 2.3 %
      - On freeboard deck: 100 tons
      - Above deck: 400 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     32,334 lbs / 14,667 Kg = 11.6 x 17.7 " / 450 mm shells or 5.8 torpedoes
   Stability (Unstable if below 1.00): 1.21
   Metacentric height 7.0 ft / 2.1 m
   Roll period: 15.7 seconds
   Steadiness   - As gun platform (Average = 50 %): 69 %
         - Recoil effect (Restricted arc if above 1.00): 0.54
   Seaboat quality  (Average = 1.00): 1.14

Hull form characteristics:
   Hull has a flush deck,
     a normal bow and a cruiser stern
   Block coefficient (normal/deep): 0.600 / 0.605
   Length to Beam Ratio: 4.93 : 1
   'Natural speed' for length: 22.04 kts
   Power going to wave formation at top speed: 57 %
   Trim (Max stability = 0, Max steadiness = 100): 61
   Bow angle (Positive = bow angles forward): 10.00 degrees
   Stern overhang: 0.00 ft / 0.00 m
   Freeboard (% = length of deck as a percentage of waterline length):
            Fore end,    Aft end
      - Forecastle:   20.00 %,  24.25 ft / 7.39 m,  19.69 ft / 6.00 m
      - Forward deck:   30.00 %,  19.69 ft / 6.00 m,  19.69 ft / 6.00 m
      - Aft deck:   35.00 %,  19.69 ft / 6.00 m,  19.69 ft / 6.00 m
      - Quarter deck:   15.00 %,  19.69 ft / 6.00 m,  19.69 ft / 6.00 m
      - Average freeboard:      20.05 ft / 6.11 m

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 87.9 %
      - Above water (accommodation/working, high = better): 147.8 %
   Waterplane Area: 34,954 Square feet or 3,247 Square metres
   Displacement factor (Displacement / loading): 103 %
   Structure weight / hull surface area: 189 lbs/sq ft or 925 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.90
      - Longitudinal: 2.49
      - Overall: 1.00
   Hull space for machinery, storage, compartmentation is adequate
   Room for accommodation and workspaces is excellent

[Kaiser Kirk]

It's interesting.
Even with aerial spotting, Fire control may be a challenge - 4 barrels, lower ROF will place real limits.
Belts decent, deck is good, not great...guessing meant to be single not multiple.
Why is there no "beam between bulkheads" ?