WesWorld

Here's a proposed German minesweeper/layer design.

R-11, Germany Minesweeper laid down 1929

Displacement:
537 t light; 566 t standard; 678 t normal; 767 t full load

Dimensions: Length overall / water x beam x draught
235.77 ft / 229.66 ft x 26.25 ft x 7.87 ft (normal load)
71.86 m / 70.00 m x 8.00 m x 2.40 m

Armament:
4 - 4.13" / 105 mm guns (2x2 guns), 35.32lbs / 16.02kg shells, 1929 Model
Dual purpose guns in deck mounts
on centreline, all forward, 1 raised mount - superfiring
2 - 1.46" / 37.0 mm guns (1x2 guns), 1.55lbs / 0.70kg shells, 1929 Model
Anti-aircraft guns in deck mount
on centreline aft, all raised guns - superfiring
4 - 1.46" / 37.0 mm guns (2x2 guns), 1.55lbs / 0.70kg shells, 1929 Model
Anti-aircraft guns in deck mounts
on side, evenly spread
Weight of broadside 151 lbs / 68 kg
Shells per gun, main battery: 180

Armour:
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 0.79" / 20 mm 0.79" / 20 mm -
2nd: 0.39" / 10 mm - -

- Conning tower: 1.97" / 50 mm

Machinery:
Diesel Internal combustion motors,
Geared drive, 1 shaft, 5,857 shp / 4,370 Kw = 22.50 kts
Range 4,000nm at 15.00 kts
Bunker at max displacement = 201 tons

Complement:
66 - 86

Cost:
£0.239 million / $0.954 million

Distribution of weights at normal displacement:
Armament: 19 tons, 2.8 %
Armour: 12 tons, 1.8 %
- Belts: 0 tons, 0.0 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 9 tons, 1.3 %
- Armour Deck: 0 tons, 0.0 %
- Conning Tower: 3 tons, 0.5 %
Machinery: 179 tons, 26.4 %
Hull, fittings & equipment: 167 tons, 24.7 %
Fuel, ammunition & stores: 141 tons, 20.8 %
Miscellaneous weights: 160 tons, 23.6 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
323 lbs / 147 Kg = 9.1 x 4.1 " / 105 mm shells or 0.3 torpedoes
Stability (Unstable if below 1.00): 1.14
Metacentric height 0.9 ft / 0.3 m
Roll period: 11.9 seconds
Steadiness - As gun platform (Average = 50 %): 66 %
- Recoil effect (Restricted arc if above 1.00): 0.36
Seaboat quality (Average = 1.00): 1.33

Hull form characteristics:
Hull has a flush deck
Block coefficient: 0.500
Length to Beam Ratio: 8.75 : 1
'Natural speed' for length: 15.15 kts
Power going to wave formation at top speed: 62 %
Trim (Max stability = 0, Max steadiness = 100): 50
Bow angle (Positive = bow angles forward): 15.00 degrees
Stern overhang: 1.64 ft / 0.50 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 16.67 ft / 5.08 m
- Forecastle (20 %): 10.60 ft / 3.23 m
- Mid (50 %): 10.60 ft / 3.23 m
- Quarterdeck (15 %): 10.60 ft / 3.23 m
- Stern: 10.60 ft / 3.23 m
- Average freeboard: 11.08 ft / 3.38 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 132.8 %
- Above water (accommodation/working, high = better): 118.1 %
Waterplane Area: 3,860 Square feet or 359 Square metres
Displacement factor (Displacement / loading): 99 %
Structure weight / hull surface area: 23 lbs/sq ft or 111 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.51
- Longitudinal: 1.82
- Overall: 0.58
Caution: Hull subject to strain in open-sea
Hull space for machinery, storage, compartmentation is cramped
Room for accommodation and workspaces is adequate
Good seaboat, rides out heavy weather easily

10 tons reserved for depth charge rails and depth charges.

150 tons reserved for mines and growth.

Isn't it a bit big? How do depth charge rails fit in with mail launching rails? Hull strength seems to be far too low as well.

to benefit from the "0.50 cross sectional hull strength" rule for light, fast combatants.

A minesweeper/layer like this isn't a "small, fast combatant" anyway. It spends most of its time doing 3-5knts.

It's intended to be a multi-purpose ship, with capability to be an escort as well as a minesweeper/layer. The mine rails would be run outside of the depth charge rails, as on the post WWII Russian DDs. A revised version follows (speed was increased, capacity fell):

R-11, Germany Minesweeper laid down 1929

Displacement:
537 t light; 566 t standard; 678 t normal; 767 t full load

Dimensions: Length overall / water x beam x draught
235.77 ft / 229.66 ft x 26.25 ft x 7.87 ft (normal load)
71.86 m / 70.00 m x 8.00 m x 2.40 m

Armament:
4 - 4.13" / 105 mm guns (2x2 guns), 35.32lbs / 16.02kg shells, 1929 Model
Dual purpose guns in deck mounts
on centreline, all forward, 1 raised mount - superfiring
2 - 1.46" / 37.0 mm guns (1x2 guns), 1.55lbs / 0.70kg shells, 1929 Model
Anti-aircraft guns in deck mount
on centreline aft, all raised guns - superfiring
4 - 1.46" / 37.0 mm guns (2x2 guns), 1.55lbs / 0.70kg shells, 1929 Model
Anti-aircraft guns in deck mounts
on side, evenly spread
Weight of broadside 151 lbs / 68 kg
Shells per gun, main battery: 180

Armour:
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 0.79" / 20 mm 0.79" / 20 mm -
2nd: 0.39" / 10 mm - -

- Conning tower: 1.97" / 50 mm

Machinery:
Diesel Internal combustion motors,
Geared drive, 1 shaft, 9,152 shp / 6,827 Kw = 25.00 kts
Range 4,000nm at 15.00 kts
Bunker at max displacement = 201 tons

Complement:
66 - 86

Cost:
£0.273 million / $1.091 million

Distribution of weights at normal displacement:
Armament: 19 tons, 2.8 %
Armour: 12 tons, 1.8 %
- Belts: 0 tons, 0.0 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 9 tons, 1.3 %
- Armour Deck: 0 tons, 0.0 %
- Conning Tower: 3 tons, 0.5 %
Machinery: 240 tons, 35.4 %
Hull, fittings & equipment: 176 tons, 26.0 %
Fuel, ammunition & stores: 141 tons, 20.8 %
Miscellaneous weights: 90 tons, 13.3 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
272 lbs / 124 Kg = 7.7 x 4.1 " / 105 mm shells or 0.3 torpedoes
Stability (Unstable if below 1.00): 1.29
Metacentric height 1.1 ft / 0.3 m
Roll period: 10.7 seconds
Steadiness - As gun platform (Average = 50 %): 50 %
- Recoil effect (Restricted arc if above 1.00): 0.28
Seaboat quality (Average = 1.00): 1.00

Hull form characteristics:
Hull has a flush deck
Block coefficient: 0.500
Length to Beam Ratio: 8.75 : 1
'Natural speed' for length: 15.15 kts
Power going to wave formation at top speed: 67 %
Trim (Max stability = 0, Max steadiness = 100): 50
Bow angle (Positive = bow angles forward): 15.00 degrees
Stern overhang: 1.64 ft / 0.50 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 16.67 ft / 5.08 m
- Forecastle (20 %): 10.60 ft / 3.23 m
- Mid (50 %): 10.60 ft / 3.23 m
- Quarterdeck (15 %): 10.60 ft / 3.23 m
- Stern: 10.60 ft / 3.23 m
- Average freeboard: 11.08 ft / 3.38 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 150.5 %
- Above water (accommodation/working, high = better): 118.1 %
Waterplane Area: 3,860 Square feet or 359 Square metres
Displacement factor (Displacement / loading): 83 %
Structure weight / hull surface area: 24 lbs/sq ft or 118 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.52
- Longitudinal: 1.90
- Overall: 0.59
Hull space for machinery, storage, compartmentation is cramped
Room for accommodation and workspaces is adequate

10 tons reserved for depth charge rails and depth charges.

80 tons reserved for mines and growth.

Here´s what Conway´s has about the german M35 type minesweepers:

"The 1935 type minesweepers - and indeed their successors - proved to be extremly well designed and suited to a variety of tasks, including escort, ASW, AA cover and minelaying. Russion naval intelligence referred to them as ´small M-type destroyers`!"

In 1929 it´s probably too early to build these kind of vessel but if you ever need a historical design to copy - voilá!

That's exactly the idea I'm aiming for here. The historical 1935 minehunters are similar in concept, if somewhat larger, to their 1916 cousins, so I'm not sure why it would be difficult to build something along lines of the concept in 1929, given the different world.

And here's a 1931 version, that's likely to be built starting in Q1, 1931.

R-11, German Minesweeper laid down 1931

Displacement:
539 t light; 568 t standard; 678 t normal; 766 t full load

Dimensions: Length overall / water x beam x draught
235.87 ft / 229.66 ft x 26.25 ft x 7.87 ft (normal load)
71.89 m / 70.00 m x 8.00 m x 2.40 m

Armament:
4 - 4.13" / 105 mm guns (2x2 guns), 35.32lbs / 16.02kg shells, 1931 Model
Dual purpose guns in deck mounts
on centreline ends, evenly spread
4 - 1.46" / 37.0 mm guns (2x2 guns), 1.55lbs / 0.70kg shells, 1929 Model
Anti-aircraft guns in deck mounts
on centreline ends, evenly spread, all raised mounts
4 - 0.79" / 20.0 mm guns in single mounts, 0.24lbs / 0.11kg shells, 1928 Model
Machine guns in deck mounts
on side, evenly spread, all raised mounts
Weight of broadside 148 lbs / 67 kg
Shells per gun, main battery: 180

Armour:
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 0.79" / 20 mm - -
2nd: 0.39" / 10 mm - -

- Conning tower: 1.97" / 50 mm

Machinery:
Diesel Internal combustion motors,
Geared drive, 2 shafts, 9,152 shp / 6,827 Kw = 25.00 kts
Range 4,000nm at 15.00 kts
Bunker at max displacement = 197 tons

Complement:
66 - 86

Cost:
£0.297 million / $1.187 million

Distribution of weights at normal displacement:
Armament: 19 tons, 2.7 %
Armour: 10 tons, 1.4 %
- Belts: 0 tons, 0.0 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 6 tons, 0.9 %
- Armour Deck: 0 tons, 0.0 %
- Conning Tower: 3 tons, 0.5 %
Machinery: 240 tons, 35.3 %
Hull, fittings & equipment: 186 tons, 27.5 %
Fuel, ammunition & stores: 139 tons, 20.4 %
Miscellaneous weights: 85 tons, 12.5 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
280 lbs / 127 Kg = 7.9 x 4.1 " / 105 mm shells or 0.3 torpedoes
Stability (Unstable if below 1.00): 1.25
Metacentric height 1.0 ft / 0.3 m
Roll period: 10.9 seconds
Steadiness - As gun platform (Average = 50 %): 65 %
- Recoil effect (Restricted arc if above 1.00): 0.28
Seaboat quality (Average = 1.00): 1.30

Hull form characteristics:
Hull has raised forecastle
Block coefficient: 0.500
Length to Beam Ratio: 8.75 : 1
'Natural speed' for length: 15.15 kts
Power going to wave formation at top speed: 67 %
Trim (Max stability = 0, Max steadiness = 100): 50
Bow angle (Positive = bow angles forward): 15.00 degrees
Stern overhang: 1.64 ft / 0.50 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 17.06 ft / 5.20 m
- Forecastle (33 %): 16.40 ft / 5.00 m (10.50 ft / 3.20 m aft of break)
- Mid (50 %): 10.50 ft / 3.20 m
- Quarterdeck (15 %): 10.50 ft / 3.20 m
- Stern: 10.50 ft / 3.20 m
- Average freeboard: 12.53 ft / 3.82 m

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 149.3 %
- Above water (accommodation/working, high = better): 121.7 %
Waterplane Area: 4,016 Square feet or 373 Square metres
Displacement factor (Displacement / loading): 86 %
Structure weight / hull surface area: 23 lbs/sq ft or 111 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.50
- Longitudinal: 2.95
- Overall: 0.59
Hull space for machinery, storage, compartmentation is cramped
Room for accommodation and workspaces is excellent
Good seaboat, rides out heavy weather easily

10 tons reserved for depth charge rails and depth charges.

25 tons reserved for minehunting/sweeping gear

50 tons reserved for mines and growth.