WesWorld

To use up some excess material I've planned this ship earlier than intended. She is broadly like the British Manxman Class. The machinery, guns and rangefinders are identical to the Mendoza Class. No belt or deck armour is fitted to reduce weight and improve speed, and if a shell hits those mines the ship is doomed anyway. She has three roles, minelaying at night, a peacetime training ship with 50-80 cadets and as a secondary cruiser if things get tough or as a destroyer flottila leader. Is 300tons misc weight enough for 100-150 mines?

General San Martin, Argentina Minelayer/Cruiser laid down 1931

Displacement:
2,582 t light; 2,726 t standard; 3,077 t normal; 3,358 t full load

Dimensions: Length overall / water x beam x draught
450.16 ft / 442.91 ft x 43.31 ft x 11.48 ft (normal load)
137.21 m / 135.00 m x 13.20 m x 3.50 m

Armament:
6 - 5.12" / 130 mm guns (3x2 guns), 67.03lbs / 30.40kg shells, 1931 Model
Breech loading guns in deck mounts with hoists
on centreline ends, majority forward, 1 raised mount - superfiring
32 - 1.46" / 37.0 mm guns (8x4 guns), 1.55lbs / 0.70kg shells, 1931 Model
Anti-aircraft guns in deck mounts
on side, evenly spread
16 - 0.79" / 20.0 mm guns (4x4 guns), 0.24lbs / 0.11kg shells, 1931 Model
Anti-aircraft guns in deck mounts
on side ends, evenly spread
Weight of broadside 456 lbs / 207 kg
Shells per gun, main battery: 300
6 - 21.0" / 533.4 mm above water torpedoes

Armour:
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 1.97" / 50 mm 0.79" / 20 mm 0.79" / 20 mm

- Conning tower: 2.76" / 70 mm

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 2 shafts, 40,800 shp / 30,436 Kw = 32.26 kts
Range 5,800nm at 15.00 kts
Bunker at max displacement = 632 tons

Complement:
206 - 268

Cost:
£1.334 million / $5.338 million

Distribution of weights at normal displacement:
Armament: 57 tons, 1.9 %
Armour: 38 tons, 1.2 %
- Belts: 0 tons, 0.0 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 25 tons, 0.8 %
- Armour Deck: 0 tons, 0.0 %
- Conning Tower: 13 tons, 0.4 %
Machinery: 1,197 tons, 38.9 %
Hull, fittings & equipment: 991 tons, 32.2 %
Fuel, ammunition & stores: 495 tons, 16.1 %
Miscellaneous weights: 300 tons, 9.7 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
1,467 lbs / 666 Kg = 21.9 x 5.1 " / 130 mm shells or 0.5 torpedoes
Stability (Unstable if below 1.00): 1.32
Metacentric height 2.3 ft / 0.7 m
Roll period: 11.9 seconds
Steadiness - As gun platform (Average = 50 %): 50 %
- Recoil effect (Restricted arc if above 1.00): 0.33
Seaboat quality (Average = 1.00): 1.12

Hull form characteristics:
Hull has a flush deck
and transom stern
Block coefficient: 0.489
Length to Beam Ratio: 10.23 : 1
'Natural speed' for length: 24.01 kts
Power going to wave formation at top speed: 62 %
Trim (Max stability = 0, Max steadiness = 100): 44
Bow angle (Positive = bow angles forward): 18.00 degrees
Stern overhang: 0.00 ft / 0.00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 22.31 ft / 6.80 m
- Forecastle (20 %): 17.06 ft / 5.20 m
- Mid (50 %): 17.06 ft / 5.20 m
- Quarterdeck (15 %): 17.06 ft / 5.20 m
- Stern: 17.06 ft / 5.20 m
- Average freeboard: 17.48 ft / 5.33 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 152.1 %
- Above water (accommodation/working, high = better): 162.8 %
Waterplane Area: 13,155 Square feet or 1,222 Square metres
Displacement factor (Displacement / loading): 95 %
Structure weight / hull surface area: 44 lbs/sq ft or 217 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.57
- Longitudinal: 1.37
- Overall: 0.62
Hull space for machinery, storage, compartmentation is cramped
Room for accommodation and workspaces is excellent

I like her but you could likely raise the range abit and cut her AA down in numbers, 12x37mm and 16 20mm should be more than enough.

As for Mines I'm working with the 1 to 1.5 tons per mine rule so you could reduce the misc weight to 200 tons with 50 going to other equipment.

I think the excessive AAA might be to discourage aircraft from doing strafing runs.

I've reduced the AA and the misc weight. I've got a lighter ship with better seakeeping. I think if it runs into enemy ships at night it should escape ok. I believe its equal to the Manxman. Mine capacity is now 150, three rails of 50 (Goes off to devleop magnetic mines)...

General San Martin, Argentina Minelayer/Cruiser laid down 1931

Displacement:
2,520 t light; 2,657 t standard; 3,077 t normal; 3,414 t full load

Dimensions: Length overall / water x beam x draught
450.27 ft / 442.91 ft x 43.31 ft x 11.48 ft (normal load)
137.24 m / 135.00 m x 13.20 m x 3.50 m

Armament:
6 - 5.12" / 130 mm guns (3x2 guns), 67.03lbs / 30.40kg shells, 1931 Model
Breech loading guns in deck mounts with hoists
on centreline ends, majority forward, 1 raised mount - superfiring
16 - 1.46" / 37.0 mm guns (4x4 guns), 1.55lbs / 0.70kg shells, 1931 Model
Anti-aircraft guns in deck mounts
on side, evenly spread
16 - 0.79" / 20.0 mm guns (8x2 guns), 0.24lbs / 0.11kg shells, 1931 Model
Anti-aircraft guns in deck mounts
on side ends, evenly spread
Weight of broadside 431 lbs / 195 kg
Shells per gun, main battery: 300
6 - 21.0" / 533.4 mm above water torpedoes

Armour:
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 1.97" / 50 mm 0.79" / 20 mm 0.79" / 20 mm

- Conning tower: 2.76" / 70 mm

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 2 shafts, 40,800 shp / 30,436 Kw = 32.26 kts
Range 7,000nm at 15.00 kts
Bunker at max displacement = 756 tons

Complement:
206 - 268

Cost:
£1.325 million / $5.299 million

Distribution of weights at normal displacement:
Armament: 54 tons, 1.8 %
Armour: 38 tons, 1.2 %
- Belts: 0 tons, 0.0 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 25 tons, 0.8 %
- Armour Deck: 0 tons, 0.0 %
- Conning Tower: 13 tons, 0.4 %
Machinery: 1,215 tons, 39.5 %
Hull, fittings & equipment: 1,013 tons, 32.9 %
Fuel, ammunition & stores: 557 tons, 18.1 %
Miscellaneous weights: 200 tons, 6.5 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
1,584 lbs / 719 Kg = 23.6 x 5.1 " / 130 mm shells or 0.5 torpedoes
Stability (Unstable if below 1.00): 1.38
Metacentric height 2.5 ft / 0.8 m
Roll period: 11.5 seconds
Steadiness - As gun platform (Average = 50 %): 50 %
- Recoil effect (Restricted arc if above 1.00): 0.31
Seaboat quality (Average = 1.00): 1.21

Hull form characteristics:
Hull has a flush deck
and transom stern
Block coefficient: 0.489
Length to Beam Ratio: 10.23 : 1
'Natural speed' for length: 24.01 kts
Power going to wave formation at top speed: 62 %
Trim (Max stability = 0, Max steadiness = 100): 41
Bow angle (Positive = bow angles forward): 18.00 degrees
Stern overhang: 0.00 ft / 0.00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 22.64 ft / 6.90 m
- Forecastle (20 %): 19.36 ft / 5.90 m
- Mid (50 %): 17.06 ft / 5.20 m
- Quarterdeck (15 %): 17.06 ft / 5.20 m
- Stern: 17.06 ft / 5.20 m
- Average freeboard: 18.13 ft / 5.53 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 149.6 %
- Above water (accommodation/working, high = better): 167.9 %
Waterplane Area: 13,155 Square feet or 1,222 Square metres
Displacement factor (Displacement / loading): 99 %
Structure weight / hull surface area: 44 lbs/sq ft or 216 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.56
- Longitudinal: 1.54
- Overall: 0.62
Hull space for machinery, storage, compartmentation is cramped
Room for accommodation and workspaces is excellent
Good seaboat, rides out heavy weather easily

she could hardly be classed as equal to Manxman on speed, which could do 40 knots IFRC!

Quoted

Hull has a flush deck
and transom stern

Not the best idea for a minelayer...

...except you want your mines come back to you. *g* ;o)

Doh!!! I'm glad you guys spotted that, I've removed it and lost 1kt of speed but got a better seaboat.
As for Manxman I thought the 40kts was an over-hyped figure and that they reached no where near that speed in service. Opinion is divided inthe books I've read.
General San Martin, Argentina Minelayer/Cruiser laid down 1931

Displacement:
2,497 t light; 2,634 t standard; 3,077 t normal; 3,432 t full load

Dimensions: Length overall / water x beam x draught
450.32 ft / 442.91 ft x 43.31 ft x 11.48 ft (normal load)
137.26 m / 135.00 m x 13.20 m x 3.50 m

Armament:
6 - 5.12" / 130 mm guns (3x2 guns), 67.03lbs / 30.40kg shells, 1931 Model
Breech loading guns in deck mounts with hoists
on centreline ends, majority forward, 1 raised mount - superfiring
16 - 1.46" / 37.0 mm guns (4x4 guns), 1.55lbs / 0.70kg shells, 1931 Model
Anti-aircraft guns in deck mounts
on side, evenly spread
16 - 0.79" / 20.0 mm guns (8x2 guns), 0.24lbs / 0.11kg shells, 1931 Model
Anti-aircraft guns in deck mounts
on side ends, evenly spread
Weight of broadside 431 lbs / 195 kg
Shells per gun, main battery: 300
6 - 21.0" / 533.4 mm above water torpedoes

Armour:
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 1.97" / 50 mm 0.79" / 20 mm 0.79" / 20 mm

- Conning tower: 2.76" / 70 mm

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 2 shafts, 40,800 shp / 30,437 Kw = 31.08 kts
Range 7,000nm at 15.00 kts
Bunker at max displacement = 798 tons

Complement:
206 - 268

Cost:
£1.321 million / $5.285 million

Distribution of weights at normal displacement:
Armament: 54 tons, 1.8 %
Armour: 38 tons, 1.2 %
- Belts: 0 tons, 0.0 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 25 tons, 0.8 %
- Armour Deck: 0 tons, 0.0 %
- Conning Tower: 13 tons, 0.4 %
Machinery: 1,215 tons, 39.5 %
Hull, fittings & equipment: 990 tons, 32.2 %
Fuel, ammunition & stores: 581 tons, 18.9 %
Miscellaneous weights: 200 tons, 6.5 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
1,546 lbs / 701 Kg = 23.1 x 5.1 " / 130 mm shells or 0.5 torpedoes
Stability (Unstable if below 1.00): 1.43
Metacentric height 2.6 ft / 0.8 m
Roll period: 11.2 seconds
Steadiness - As gun platform (Average = 50 %): 50 %
- Recoil effect (Restricted arc if above 1.00): 0.30
Seaboat quality (Average = 1.00): 1.35

Hull form characteristics:
Hull has a flush deck
Block coefficient: 0.489
Length to Beam Ratio: 10.23 : 1
'Natural speed' for length: 21.05 kts
Power going to wave formation at top speed: 60 %
Trim (Max stability = 0, Max steadiness = 100): 37
Bow angle (Positive = bow angles forward): 18.00 degrees
Stern overhang: 0.00 ft / 0.00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 22.80 ft / 6.95 m
- Forecastle (20 %): 19.36 ft / 5.90 m
- Mid (50 %): 17.06 ft / 5.20 m
- Quarterdeck (15 %): 17.06 ft / 5.20 m
- Stern: 17.06 ft / 5.20 m
- Average freeboard: 18.14 ft / 5.53 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 149.6 %
- Above water (accommodation/working, high = better): 161.4 %
Waterplane Area: 12,654 Square feet or 1,176 Square metres
Displacement factor (Displacement / loading): 99 %
Structure weight / hull surface area: 44 lbs/sq ft or 213 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.56
- Longitudinal: 1.51
- Overall: 0.61
Hull space for machinery, storage, compartmentation is cramped
Room for accommodation and workspaces is excellent
Good seaboat, rides out heavy weather easily

Quoted

Originally posted by 1Big Rich

Quoted

Hull has a flush deck
and transom stern

Not the best idea for a minelayer...

Wow...I missed that too.

In reguards to Manxman I've read that she was capable of 35 knots comfortably.

Question:
Minelayer + transom stern = bad idea...
... but when was that exactly known?

When HMS Adventure was built with a transom in the 1920s, first ship such built for the RN.

The final plan for these ships.