Idea for a smallish subchaser-type ship

[Sachmle]

J-101, Deutsche Reich U-bootenjäger laid down 1920 (Engine 1916)

Displacement:
   100 t light; 105 t standard; 120 t normal; 132 t full load

Dimensions: Length overall / water x beam x draught
   137.81 ft / 135.17 ft x 16.90 ft x 4.10 ft (normal load)
   42.00 m / 41.20 m x 5.15 m  x 1.25 m

Armament:
      1 - 3.46" / 88.0 mm guns in single mounts, 22.05lbs / 10.00kg shells, 1920 Model
     Quick firing gun in deck mount
     on centreline forward
      2 - 1.46" / 37.0 mm guns in single mounts, 1.55lbs / 0.70kg shells, 1920 Model
     Anti-aircraft guns in deck mounts
     on side, all amidships
      4 - 0.30" / 7.7 mm guns in single mounts, 0.01lbs / 0.01kg shells, 1920 Model
     Machine guns in deck mounts
     on side, evenly spread, all raised mounts
   Weight of broadside 25 lbs / 11 kg
   Shells per gun, main battery: 200

Armour:
   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   0.98" / 25 mm         -               -
   2nd:   0.59" / 15 mm         -               -
   3rd:   0.39" / 10 mm         -               -

   - Conning tower: 0.98" / 25 mm

Machinery:
   Diesel Internal combustion motors,
   Direct drive, 1 shaft, 825 shp / 616 Kw = 17.16 kts
   Range 1,200nm at 14.25 kts
   Bunker at max displacement = 27 tons

Complement:
   17 - 23

Cost:
   £0.024 million / $0.098 million

Distribution of weights at normal displacement:
   Armament: 3 tons, 2.5 %
   Armour: 3 tons, 2.2 %
      - Belts: 0 tons, 0.0 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 2 tons, 1.8 %
      - Armour Deck: 0 tons, 0.0 %
      - Conning Tower: 1 tons, 0.4 %
   Machinery: 31 tons, 25.5 %
   Hull, fittings & equipment: 59 tons, 48.6 %
   Fuel, ammunition & stores: 20 tons, 17.0 %
   Miscellaneous weights: 5 tons, 4.2 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     177 lbs / 80 Kg = 8.5 x 3.5 " / 88 mm shells or 0.3 torpedoes
   Stability (Unstable if below 1.00): 1.17
   Metacentric height 0.5 ft / 0.1 m
   Roll period: 10.4 seconds
   Steadiness   - As gun platform (Average = 50 %): 70 %
         - Recoil effect (Restricted arc if above 1.00): 0.22
   Seaboat quality  (Average = 1.00): 1.27

Hull form characteristics:
   Hull has a flush deck
   Block coefficient: 0.450
   Length to Beam Ratio: 8.00 : 1
   'Natural speed' for length: 11.63 kts
   Power going to wave formation at top speed: 60 %
   Trim (Max stability = 0, Max steadiness = 100): 55
   Bow angle (Positive = bow angles forward): 12.10 degrees
   Stern overhang: -1.64 ft / -0.50 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      12.30 ft / 3.75 m
      - Forecastle (21 %):   6.56 ft / 2.00 m
      - Mid (50 %):      6.56 ft / 2.00 m
      - Quarterdeck (15 %):   6.56 ft / 2.00 m
      - Stern:      6.56 ft / 2.00 m
      - Average freeboard:   7.04 ft / 2.15 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 107.6 %
      - Above water (accommodation/working, high = better): 102.0 %
   Waterplane Area: 1,388 Square feet or 129 Square metres
   Displacement factor (Displacement / loading): 129 %
   Structure weight / hull surface area: 23 lbs/sq ft or 112 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.86
      - Longitudinal: 3.64
      - Overall: 1.00
   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

5t 15 1916 Depth Charges w/ racks

[Guinness]

I suspect this has more freeboard than it really needs. Here's a picture of a (more or less) standard US sub chaser from WW1:



These are, after all, small coastal boats for the most part.

If you reduce freeboard some, I suspect you could shrink her a bit more.

[snip]

I like these. Ireland might be interested in buying some of these, or the licenses to build them.

[Logi]

Hmm I'm glad to see you were thinking of them too Snip, I was going to include them in my footnotes for Eire.

[snip]

bit off topic: did you get all the data compiled? I could use it ASAP

[Logi]

Yea I was going to send it to you yesterday night, but my internet shut down and I lost the message. Expect the PM in about an hour.

[snip]

ok thanks a ton

Sorry for hijacking the thread

[Sachmle]

Redesign. Also note that the 37mm AA could quite easily be trained downward towards subs, MTBs, or other small craft. Also could be used as a "Coast Guard" vessel.

J-101, Deutsche Reich U-bootenjäger laid down 1920 (Engine 1916)

Displacement:
   75 t light; 79 t standard; 86 t normal; 92 t full load

Dimensions: Length overall / water x beam x draught
   108.91 ft / 104.99 ft x 13.94 ft x 5.41 ft (normal load)
   33.20 m / 32.00 m x 4.25 m  x 1.65 m

Armament:
     1 - 3.46" / 88.0 mm guns in single mounts, 22.05lbs / 10.00kg shells, 1920 Model
     Quick firing gun in deck mount
     on centreline forward
     2 - 1.46" / 37.0 mm guns in single mounts, 1.55lbs / 0.70kg shells, 1920 Model
     Anti-aircraft guns in deck mounts
     on side, all amidships
     4 - 0.30" / 7.7 mm guns in single mounts, 0.01lbs / 0.01kg shells, 1920 Model
     Machine guns in deck mounts
     on side, evenly spread, all raised mounts
   Weight of broadside 25 lbs / 11 kg
   Shells per gun, main battery: 140

Armour:
  - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   0.98" / 25 mm         -               -
   2nd:   0.59" / 15 mm         -               -
   3rd:   0.39" / 10 mm         -               -

  - Conning tower: 0.98" / 25 mm

Machinery:
   Petrol Internal combustion motors,
   Direct drive, 2 shafts, 700 shp / 523 Kw = 16.98 kts
   Range 1,050nm at 12.00 kts
   Bunker at max displacement = 13 tons

Complement:
   13 - 18

Cost:
   £0.021 million / $0.083 million

Distribution of weights at normal displacement:
   Armament: 3 tons, 3.5 %
   Armour: 3 tons, 3.0 %
      - Belts: 0 tons, 0.0 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 2 tons, 2.5 %
      - Armour Deck: 0 tons, 0.0 %
      - Conning Tower: 0 tons, 0.5 %
   Machinery: 26 tons, 30.3 %
   Hull, fittings & equipment: 40 tons, 47.0 %
   Fuel, ammunition & stores: 11 tons, 12.7 %
   Miscellaneous weights: 3 tons, 3.5 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     77 lbs / 35 Kg = 3.7 x 3.5 " / 88 mm shells or 0.2 torpedoes
   Stability (Unstable if below 1.00): 1.12
   Metacentric height 0.3 ft / 0.1 m
   Roll period: 10.3 seconds
   Steadiness   - As gun platform (Average = 50 %): 70 %
         - Recoil effect (Restricted arc if above 1.00): 0.42
   Seaboat quality  (Average = 1.00): 1.30

Hull form characteristics:
   Hull has raised forecastle
   Block coefficient: 0.380
   Length to Beam Ratio: 7.53 : 1
   'Natural speed' for length: 10.25 kts
   Power going to wave formation at top speed: 64 %
   Trim (Max stability = 0, Max steadiness = 100): 54
   Bow angle (Positive = bow angles forward): 14.20 degrees
   Stern overhang: 1.64 ft / 0.50 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      9.02 ft / 2.75 m
      - Forecastle (20 %):   7.38 ft / 2.25 m (7.22 ft / 2.20 m aft of break)
      - Mid (50 %):      5.74 ft / 1.75 m
      - Quarterdeck (15 %):   5.74 ft / 1.75 m
      - Stern:      5.74 ft / 1.75 m
      - Average freeboard:   6.42 ft / 1.96 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 129.0 %
      - Above water (accommodation/working, high = better): 79.5 %
   Waterplane Area: 893 Square feet or 83 Square metres
   Displacement factor (Displacement / loading): 105 %
   Structure weight / hull surface area: 21 lbs/sq ft or 103 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.81
      - Longitudinal: 6.97
      - Overall: 1.00
   Hull space for machinery, storage, compartmentation is cramped
   Room for accommodation and workspaces is cramped
   Ship has slow, easy roll, a good, steady gun platform
   Good seaboat, rides out heavy weather easily

3t 9 1916 Depth Charges w/ racks

[Carthaginian]

A nice little vessel.
Small, economical, and fast enough.

[Guinness]

Just cuz these are similar to this topic:

http://www.history.navy.mil/photos/images/s-file/s584124.jpg
http://www.history.navy.mil/photos/images/s-file/s584125.jpg
http://www.history.navy.mil/photos/images/s-file/s584122.jpg
http://www.history.navy.mil/photos/images/s-file/s584121.jpg

[P3D]

Too much armament. You need at least 11 people to operate the guns (3+4+4).
For coastguard stuff I'd rather have a vessel with W/T.

[Sachmle]

Too much armament. You need at least 11 people to operate the guns (3+4+4).
For coastguard stuff I'd rather have a vessel with W/T.

Interesting on the guns, I hadn't considered that. As to W/T, it has one. We don't have to do misc weight for short range W/T anymore, remember?

[Carthaginian]

P3D - I doubt that they'd be manning all the guns, all the time.
You'd probably have different 'attack stations':
1.) Submerged Attack: 4 - 6 men on the DC racks, and others manning the ship.
2.) Surface Attack: 4 - 6 men on the 88mm, 4 on standby for the 37mm, and others manning the ship.
3.) Air Action: 4 men on the 37mm, 4 men on the 7mm's and others manning the ship.

It's a VERY small ship, and probably only needs 6-8 men to actually operate it.
1.) Commander
2.) Helmsman
3.) Navigator
4.) Engineer
5.) Engineer's Mate*
6.) Engineer's Mate*

The rest of the men would include a dedicated Weapon's Officer (for overseeing the 88mm and DC's), several men cross-trained as Engineer's Mates^ and Gunner's Mates, and a backup for the Navigator who could also do some other work about the ship. The 88mm could operate for a couple of minutes on the ammo in the ready locker, so technically, 3 men could handle it for the crucial first couple of minutes if a sub surfaces. The 37mm would be similar- one handler and one gunner would be able to take on most of the 'immediate need' situations.

*One Per Engine
^ All the Engineer's Mates would be cross-trained

[P3D]

Sorry, but I just cannot see a 75t boat taking more AA armament than the latest class of DKB destroyers. Also, a full-power 88mm gun might be too heavy, so most probably it is a short-barreled gun:
http://navweaps.com/Weapons/WNGER_88mm-30_skc97.htm

The US subchasers had a crew of 22+2 officers - with less guns, so I'd doubt you could get much below it (even given the USN tendency to cram the highest amount of people in any vessel, then some), unless you are willing to forego detection equipment.

http://www.subchaser.org/statistics

[Sachmle]

J-101, Deutsche Reich U-bootenjäger laid down 1920 (Engine 1916)

Displacement:
   75 t light; 79 t standard; 86 t normal; 92 t full load

Dimensions: Length overall / water x beam x draught
   108.91 ft / 104.99 ft x 13.94 ft x 5.41 ft (normal load)
   33.20 m / 32.00 m x 4.25 m  x 1.65 m

Armament:
      1 - 3.46" / 88.0 mm guns in single mounts, 22.05lbs / 10.00kg shells, 1920 Model
     Quick firing gun in deck mount
     on centreline forward
      4 - 0.30" / 7.7 mm guns in single mounts, 0.02lbs / 0.01kg shells, 1920 Model
     Machine guns in deck mounts
     on side, evenly spread
   Weight of broadside 22 lbs / 10 kg
   Shells per gun, main battery: 200

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

   - Conning tower: 0.98" / 25 mm

Machinery:
   Petrol Internal combustion motors,
   Direct drive, 2 shafts, 720 shp / 537 Kw = 17.09 kts
   Range 1,075nm at 12.00 kts
   Bunker at max displacement = 13 tons

Complement:
   13 - 18

Cost:
   £0.020 million / $0.081 million

Distribution of weights at normal displacement:
   Armament: 3 tons, 3.0 %
   Armour: 2 tons, 2.7 %
      - Belts: 0 tons, 0.0 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 2 tons, 2.2 %
      - Armour Deck: 0 tons, 0.0 %
      - Conning Tower: 0 tons, 0.5 %
   Machinery: 27 tons, 31.2 %
   Hull, fittings & equipment: 40 tons, 46.4 %
   Fuel, ammunition & stores: 11 tons, 13.3 %
   Miscellaneous weights: 3 tons, 3.5 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     76 lbs / 35 Kg = 3.7 x 3.5 " / 88 mm shells or 0.2 torpedoes
   Stability (Unstable if below 1.00): 1.12
   Metacentric height 0.3 ft / 0.1 m
   Roll period: 10.3 seconds
   Steadiness   - As gun platform (Average = 50 %): 71 %
         - Recoil effect (Restricted arc if above 1.00): 0.37
   Seaboat quality  (Average = 1.00): 1.28

Hull form characteristics:
   Hull has raised forecastle
   Block coefficient: 0.380
   Length to Beam Ratio: 7.53 : 1
   'Natural speed' for length: 10.25 kts
   Power going to wave formation at top speed: 65 %
   Trim (Max stability = 0, Max steadiness = 100): 55
   Bow angle (Positive = bow angles forward): 14.20 degrees
   Stern overhang: 1.64 ft / 0.50 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      9.02 ft / 2.75 m
      - Forecastle (20 %):   7.38 ft / 2.25 m (7.22 ft / 2.20 m aft of break)
      - Mid (50 %):      5.74 ft / 1.75 m
      - Quarterdeck (15 %):   5.74 ft / 1.75 m
      - Stern:      5.74 ft / 1.75 m
      - Average freeboard:   6.42 ft / 1.96 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 129.1 %
      - Above water (accommodation/working, high = better): 79.5 %
   Waterplane Area: 893 Square feet or 83 Square metres
   Displacement factor (Displacement / loading): 108 %
   Structure weight / hull surface area: 21 lbs/sq ft or 102 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.81
      - Longitudinal: 6.93
      - Overall: 1.00
   Hull space for machinery, storage, compartmentation is cramped
   Room for accommodation and workspaces is cramped
   Ship has slow, easy roll, a good, steady gun platform
   Good seaboat, rides out heavy weather easily

3t 9 1916 Depth Charges w/ racks