WesWorld

Project under consideration for the 1938 Buiilding Program

Project 38A - Galeb, Yugoslavia Multi-purpose Minecraft laid down 1938

Displacement:
551 t light; 574 t standard; 644 t normal; 700 t full load

Dimensions: Length overall / water x beam x draught
201.42 ft / 196.85 ft x 24.74 ft x 8.50 ft (normal load)
61.39 m / 60.00 m x 7.54 m x 2.59 m

Armament:
2 - 4.13" / 105 mm guns in single mounts, 35.32lbs / 16.02kg shells, 1936 Model
Dual purpose guns in deck mounts with hoists
on centreline ends, evenly spread, all raised mounts
2 - 1.57" / 40.0 mm guns (1x2 guns), 1.95lbs / 0.88kg shells, 1936 Model
Anti-aircraft guns in deck mount
on centreline aft, all raised guns - superfiring
8 - 0.79" / 20.0 mm guns (4x2 guns), 0.24lbs / 0.11kg shells, 1928 Model
Anti-aircraft guns in deck mounts
on side, evenly spread, all raised mounts
Weight of broadside 76 lbs / 35 kg
Shells per gun, main battery: 240

Armour:
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 1.18" / 30 mm 0.59" / 15 mm 1.18" / 30 mm
2nd: 0.59" / 15 mm 0.39" / 10 mm -
3rd: 0.59" / 15 mm - -

Machinery:
Diesel Internal combustion motors,
Geared drive, 2 shafts, 2,514 shp / 1,876 Kw = 18.00 kts
Range 4,800nm at 12.00 kts
Bunker at max displacement = 126 tons

Complement:
63 - 83

Cost:
£0.208 million / $0.833 million

Distribution of weights at normal displacement:
Armament: 10 tons, 1.5 %
Armour: 7 tons, 1.0 %
- Belts: 0 tons, 0.0 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 7 tons, 1.0 %
- Armour Deck: 0 tons, 0.0 %
- Conning Tower: 0 tons, 0.0 %
Machinery: 69 tons, 10.7 %
Hull, fittings & equipment: 286 tons, 44.4 %
Fuel, ammunition & stores: 94 tons, 14.5 %
Miscellaneous weights: 180 tons, 27.9 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
1,085 lbs / 492 Kg = 30.7 x 4.1 " / 105 mm shells or 0.7 torpedoes
Stability (Unstable if below 1.00): 1.04
Metacentric height 0.7 ft / 0.2 m
Roll period: 12.8 seconds
Steadiness - As gun platform (Average = 50 %): 42 %
- Recoil effect (Restricted arc if above 1.00): 0.43
Seaboat quality (Average = 1.00): 1.33

Hull form characteristics:
Hull has raised forecastle, rise forward of midbreak, low quarterdeck
Block coefficient: 0.545
Length to Beam Ratio: 7.96 : 1
'Natural speed' for length: 14.03 kts
Power going to wave formation at top speed: 58 %
Trim (Max stability = 0, Max steadiness = 100): 27
Bow angle (Positive = bow angles forward): 15.00 degrees
Stern overhang: 0.00 ft / 0.00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 17.06 ft / 5.20 m
- Forecastle (20 %): 15.75 ft / 4.80 m (15.09 ft / 4.60 m aft of break)
- Mid (35 %): 10.50 ft / 3.20 m (9.84 ft / 3.00 m aft of break)
- Quarterdeck (35 %): 7.87 ft / 2.40 m (8.86 ft / 2.70 m before break)
- Stern: 6.56 ft / 2.00 m
- Average freeboard: 10.51 ft / 3.20 m

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 77.8 %
- Above water (accommodation/working, high = better): 107.4 %
Waterplane Area: 3,383 Square feet or 314 Square metres
Displacement factor (Displacement / loading): 161 %
Structure weight / hull surface area: 45 lbs/sq ft or 221 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 1.01
- Longitudinal: 4.41
- Overall: 1.17
Hull space for machinery, storage, compartmentation is excellent
Room for accommodation and workspaces is adequate
Good seaboat, rides out heavy weather easily

Miscellaneous weight - 180 tons reserved for minesweeping gear and up to 30 mines dependant upon employment

Quoted

Originally posted by BruceDuncanMiscellaneous weight - 180 tons reserved for minesweeping gear and up to 30 mines dependant upon employment

I do like combination sweeper/layers: they appeal to my sense of humour. She seems quite quick for her size and type, but I don't know if there's some doctrinal reason for that - defensive minelaying and sweeping only really needs 8-12 knots, whilst offensive work would need destroyer-type speeds, at least for a layer.

She's also got quite marginal stability, and an awful lot of residual strength. I'd suggest reducing hull depth to mitigate these problems; you might well be able to take 50-100 tons off with careful sizing.

Quoted

Originally posted by RLBH

Quoted

Originally posted by BruceDuncanMiscellaneous weight - 180 tons reserved for minesweeping gear and up to 30 mines dependant upon employment

I do like combination sweeper/layers: they appeal to my sense of humour. She seems quite quick for her size and type, but I don't know if there's some doctrinal reason for that - defensive minelaying and sweeping only really needs 8-12 knots, whilst offensive work would need destroyer-type speeds, at least for a layer.

She's also got quite marginal stability, and an awful lot of residual strength. I'd suggest reducing hull depth to mitigate these problems; you might well be able to take 50-100 tons off with careful sizing.

She's based on the OTL German M35, which also were called upon as convoy escorts - perhaps a bit under-gunned for that role.

I'm not happy with the stability either. I'm still new to Springsharp - which parameter, or parameters, impact hull depth? The 180 tons miscellaneous was just a SWAG.

Quoted

Originally posted by BruceDuncanShe's based on the OTL German M35, which also were called upon as convoy escorts - perhaps a bit under-gunned for that role.

I'm not happy with the stability either. I'm still new to Springsharp - which parameter, or parameters, impact hull depth? The 180 tons miscellaneous was just a SWAG.

Hull depth is treated in a slightly odd way in SpringSharp: normally, you'd select a depth, calculate weights and such, and then find the draught (hence freeboard) corresponding to it. In SpringSharp, you specify draught and freeboard, and the depth is the sum of the two; to cut depth, you'd want to reduce one or the other.

180 tons probably is a bit on the high side for sweeping gear; ISTR that adding sweeps to the River-class frigates entailed an addition of about 50 tons. That'll all be on the main deck, so cutting back there would be good for your topweight and improve stability, although maybe not right back to the 50 ton figure.

I may try to write a short article in the next couple of weeks on naval architecture as applied to SpringSharp, and how to design a ship, if people are interested.

Quoted

Originally posted by RLBH

Quoted

Originally posted by BruceDuncanShe's based on the OTL German M35, which also were called upon as convoy escorts - perhaps a bit under-gunned for that role.

I'm not happy with the stability either. I'm still new to Springsharp - which parameter, or parameters, impact hull depth? The 180 tons miscellaneous was just a SWAG.

Hull depth is treated in a slightly odd way in SpringSharp: normally, you'd select a depth, calculate weights and such, and then find the draught (hence freeboard) corresponding to it. In SpringSharp, you specify draught and freeboard, and the depth is the sum of the two; to cut depth, you'd want to reduce one or the other.

180 tons probably is a bit on the high side for sweeping gear; ISTR that adding sweeps to the River-class frigates entailed an addition of about 50 tons. That'll all be on the main deck, so cutting back there would be good for your topweight and improve stability, although maybe not right back to the 50 ton figure.

I may try to write a short article in the next couple of weeks on naval architecture as applied to SpringSharp, and how to design a ship, if people are interested.

Thanks! I will play with the parameters. And I for one would really appreciate the article you mention - and I bet I will not be alone.

I took counsel with the feedback and comments, and I think that Revision B looks better - certainly smaller, more build-able. Additional comments welcome!

Project 38B - Galeb, Yugoslavia Multi-purpose Minecraft laid down 1938

Displacement:
499 t light; 523 t standard; 573 t normal; 613 t full load

Dimensions: Length overall / water x beam x draught
195.42 ft / 191.93 ft x 24.74 ft x 7.55 ft (normal load)
59.56 m / 58.50 m x 7.54 m x 2.30 m

Armament:
2 - 4.13" / 105 mm guns in single mounts, 35.32lbs / 16.02kg shells, 1936 Model
Dual purpose guns in deck mounts with hoists
on centreline ends, evenly spread, all raised mounts
2 - 1.57" / 40.0 mm guns (1x2 guns), 1.95lbs / 0.88kg shells, 1936 Model
Anti-aircraft guns in deck mount
on centreline aft, all raised guns - superfiring
8 - 0.79" / 20.0 mm guns (4x2 guns), 0.24lbs / 0.11kg shells, 1928 Model
Anti-aircraft guns in deck mounts
on side, evenly spread, all raised mounts
Weight of broadside 76 lbs / 35 kg
Shells per gun, main battery: 280

Armour:
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 1.18" / 30 mm 0.59" / 15 mm 1.18" / 30 mm
2nd: 0.59" / 15 mm 0.39" / 10 mm -
3rd: 0.59" / 15 mm - -

Machinery:
Diesel Internal combustion motors,
Geared drive, 2 shafts, 2,398 shp / 1,789 Kw = 18.00 kts
Range 3,600nm at 12.00 kts
Bunker at max displacement = 90 tons

Complement:
58 - 76

Cost:
£0.196 million / $0.782 million

Distribution of weights at normal displacement:
Armament: 10 tons, 1.7 %
Armour: 7 tons, 1.1 %
- Belts: 0 tons, 0.0 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 7 tons, 1.1 %
- Armour Deck: 0 tons, 0.0 %
- Conning Tower: 0 tons, 0.0 %
Machinery: 66 tons, 11.5 %
Hull, fittings & equipment: 317 tons, 55.3 %
Fuel, ammunition & stores: 74 tons, 12.9 %
Miscellaneous weights: 100 tons, 17.4 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
1,145 lbs / 519 Kg = 32.4 x 4.1 " / 105 mm shells or 0.7 torpedoes
Stability (Unstable if below 1.00): 1.10
Metacentric height 0.7 ft / 0.2 m
Roll period: 12.0 seconds
Steadiness - As gun platform (Average = 50 %): 37 %
- Recoil effect (Restricted arc if above 1.00): 0.40
Seaboat quality (Average = 1.00): 1.06

Hull form characteristics:
Hull has raised forecastle, rise forward of midbreak, low quarterdeck
Block coefficient: 0.560
Length to Beam Ratio: 7.76 : 1
'Natural speed' for length: 13.85 kts
Power going to wave formation at top speed: 59 %
Trim (Max stability = 0, Max steadiness = 100): 26
Bow angle (Positive = bow angles forward): 12.00 degrees
Stern overhang: 0.00 ft / 0.00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 16.40 ft / 5.00 m
- Forecastle (20 %): 15.42 ft / 4.70 m (14.76 ft / 4.50 m aft of break)
- Mid (35 %): 10.17 ft / 3.10 m (9.51 ft / 2.90 m aft of break)
- Quarterdeck (35 %): 7.55 ft / 2.30 m (8.53 ft / 2.60 m before break)
- Stern: 6.56 ft / 2.00 m
- Average freeboard: 10.21 ft / 3.11 m

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 70.9 %
- Above water (accommodation/working, high = better): 111.7 %
Waterplane Area: 3,345 Square feet or 311 Square metres
Displacement factor (Displacement / loading): 182 %
Structure weight / hull surface area: 53 lbs/sq ft or 261 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 1.20
- Longitudinal: 4.92
- Overall: 1.39
Hull space for machinery, storage, compartmentation is excellent
Room for accommodation and workspaces is adequate

Miscellaneous weight - 100 tons reserved for minesweeping gear and up to 30 mines dependant upon employment

I do like how extra hull strength is reserved to deal with explosions in close proximity to the hull.